The aim of this study was to compare the inflammatory responses between male and female soccer players for a period of 48 hours after an official match. Blood samples were taken from 83 subjects (22 elite male and 21 elite female soccer players and 20 male and 20 female inactive individuals) in the morning of the game day, immediately after the soccer game and 24 and 48 hours after the match. Average relative exercise intensity during the match was similar in male and female players, as indicated by mean heart rate that was 86.9 ± 4.3 and 85.6 ± 2.3% of maximal heart rate (p 0.23), respectively. Interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α) increased 2- to 4-fold above resting values, peaking immediately after the match. C-reactive protein (CRP) and creatine kinase peaked 24 hours after the match. Interleukin 6, CRP, and creatine kinase responses were similar in male and female players, but the peak in TNF-α was 18% higher in male players. Interleukin 6, TNF-α, and CRP at rest were lower in male and female players compared with the control subjects, suggesting a protective effect of regular exercise training regarding the inflammatory profile. The results of this study show that a soccer match induces significant inflammatory responses in both male and female players, with only TNF-α peak values being lower in females. Because of the effects of inflammatory responses on performance and health of the players, it is suggested that coaches and trainers should adjust exercise training programs after a match to promote recovery and protect the athletes' health. © 2015 National Strength and Conditioning Association.

{This study examined the relationship between hamstrings-to-quadriceps strength ratio (H:Q) and relative strength of the knee extensors in elite soccer players. Peak torque was measured during isokinetic knee extension/flexion at angular velocities of 60°·s-1, 180°·s-1 and 300°·s-1. 18 professional players were divided into 2 groups, depending on their H:Q at 60°·s-1. Players in the lower H:Q group (n=7) had significantly smaller H:Q ratios compared with the higher H:Q group (n=11) at all angular velocities (60°·s-1: 49.2%; 95% CI: 61.3-57.8% vs. 59.5%; 95% CI: 52.2-46.2%

Inflammatory responses and muscle damage indices were compared between four popular team sports at an elite level. Seventy two male elite players of four team sports: soccer (n = 18), basketball (n = 18), volleyball (n = 18) and handball (n = 18), completed an official match, while 18 non-athletes served as controls. Blood samples were drawn before, immediately after and 13 and 37 h post-match. Soccer produced the greatest increase in inflammatory cytokines (tumor necrosis factor-alpha and interleukin-6), which were increased by 3-4 fold immediately after the game, as well as in C-reactive protein, which was increased by threefold in the next morning after the match. Metabolic stress (urea, ammonia and cortisol) and muscle damage indices (creatine kinase and lactate dehydrogenase) were also higher after soccer, with creatine kinase responses being almost 2-3 times higher than the other sports. Volleyball showed the smallest increase in inflammation and muscle damage markers compared with the other three sports. © 2014 © 2014 Taylor & Francis.

The aim of this study was to compare the inflammatory responses between male and female soccer players for a period of 48 hours after an official match. Blood samples were taken from 83 subjects (22 elite male and 21 elite female soccer players and 20 male and 20 female inactive individuals) in the morning of the game day, immediately after the soccer game and 24 and 48 hours after the match. Average relative exercise intensity during the match was similar in male and female players, as indicated by mean heart rate that was 86.9 ± 4.3 and 85.6 ± 2.3% of maximal heart rate (p 0.23), respectively. Interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α) increased 2- to 4-fold above resting values, peaking immediately after the match. C-reactive protein (CRP) and creatine kinase peaked 24 hours after the match. Interleukin 6, CRP, and creatine kinase responses were similar in male and female players, but the peak in TNF-α was 18% higher in male players. Interleukin 6, TNF-α, and CRP at rest were lower in male and female players compared with the control subjects, suggesting a protective effect of regular exercise training regarding the inflammatory profile. The results of this study show that a soccer match induces significant inflammatory responses in both male and female players, with only TNF-α peak values being lower in females. Because of the effects of inflammatory responses on performance and health of the players, it is suggested that coaches and trainers should adjust exercise training programs after a match to promote recovery and protect the athletes' health. © 2015 National Strength and Conditioning Association.

{This study examined the relationship between hamstrings-to-quadriceps strength ratio (H:Q) and relative strength of the knee extensors in elite soccer players. Peak torque was measured during isokinetic knee extension/flexion at angular velocities of 60°·s-1, 180°·s-1 and 300°·s-1. 18 professional players were divided into 2 groups, depending on their H:Q at 60°·s-1. Players in the lower H:Q group (n=7) had significantly smaller H:Q ratios compared with the higher H:Q group (n=11) at all angular velocities (60°·s-1: 49.2%; 95% CI: 61.3-57.8% vs. 59.5%; 95% CI: 52.2-46.2%

The lipid profile of elite basketball and soccer athletes was evaluated and compared with that of inactive individuals. Total cholesterol (T-C), low and high density lipoprotein cholesterol (LDL-C and HDL-C), and triglyceride (TG) concentration were measured in the morning and after a soccer or a basketball match. All parameters of lipid profile measured at a fasted and resting state, except HDL-C, were lower in the athletes compared with the controls (p < 0.01). The soccer match resulted in a greater decrease in TG (78.3 ± 6.7 to 70.7 ± 6.3, p < 0.01), T-C (179.3 ± 10.7 to 171.6 ± 9.6, p < 0.01), LDL-C (110.9 ± 8.9 to 103.5 ± 7.5, p < 0.01) compared with the basketball match that resulted only in a decrease in LDL-C (126.8 ± 9.5 to 117.3 ± 9.1, p < 0.01) and an increase in HDL-C that was similar to that observed after the soccer match (9-12%). These findings support the beneficial effects of basketball and soccer on cardiovascular health. © 2013 © Taylor & Francis Group, LLC.

This study examined the effects of baseline flexibility and vertical jump ability on straight leg raise range of motion (ROM) and counter-movement jump performance (CMJ) following different volumes of stretching and potentiating exercises. ROM and CMJ were measured after two different warm-up protocols involving static stretching and potentiating exercises. Three groups of elite athletes (10 male, 14 female artistic gymnasts and 10 female rhythmic gymnasts) varying greatly in ROM and CMJ, performed two warm-up routines. One warm-up included short (15 s) static stretching followed by 5 tuck jumps, while the other included long static stretching (30 s) followed by 3x5 tuck jumps. ROM and CMJ were measured before, during and for 12 min after the two warm-up routines. Three-way ANOVA showed large differences between the three groups in baseline ROM and CMJ performance. A type of warm-up x time interaction was found for both ROM (p = 0.031) and CMJ (p = 0.016). However, all athletes, irrespective of group, responded in a similar fashion to the different warm-up protocols for both ROM and CMJ, as indicated from the lack of significant interactions for group (condition x group, time x group or condition x time x group). In the short warm-up protocol, ROM was not affected by stretching, while in the long warm-up protocol ROM increased by 5.9% ± 0.7% (p = 0.001) after stretching. Similarly, CMJ remained unchanged after the short warm-up protocol, but increased by 4.6 ± 0.9% (p = 0.012) 4 min after the long warmup protocol, despite the increased ROM. It is concluded that the initial levels of flexibility and CMJ performance do not alter the responses of elite gymnasts to warm-up protocols differing in stretching and potentiating exercise volumes. Furthermore, 3 sets of 5 tuck jumps result in a relatively large increase in CMJ performance despite an increase in flexibility in these highly-trained athletes. © Journal of Sports Science and Medicine.

This study investigated the effects of muscle action type during conditioning activity (half-squat) on subsequent vertical jump performance. Fourteen track and field athletes (relative half-squat of 2.3 ± 0.3 times their body weight) completed 4 main trials in a randomized and counterbalanced order 5-7 days apart: (a) concentric (CON) halfsquats: 7.5 ± 1.2 repetitions against 90% of 1 repetition maximum (1RM), (b) eccentric (ECC) half-squats: 9.3 ± 1.5 repetitions against 70% of 1RM, and (c) 3 sets of 3-second maximal isometric (ISO) half-squats, (d) a control (CTRL) trial, where subjects rested for 10 minutes. The number of repetitions in CON and ECC was adjusted so that the impulse of the vertical ground reaction force was similar to ISO. Countermovement vertical jump (CMJ) performance was evaluated for 21 minutes after each main trial. Countermovement vertical jump performance in ISO was higher than CTRL from the second to the 10th minute of recovery, whereas CMJ performance in ECC was higher than CTRL from the sixth and 10th minute of recovery. Analysis of the peak individual responses revealed an increase in CMJ performance compared with baseline only in ISO (3.06 1.2%; p = 0.045), whereas no significant increases were observed in ECC and CON. Peak CMJ performance for all subjects in ISO and ECC was achieved within 2-10 minutes after the conditioning muscle actions. Isometric were more effective than CON and ECC muscle actions in increasing explosive leg performance when the impulse of the ground reaction force of the conditioning exercise was equated. © 2014 National Strength and Conditioning Association.

{This study investigated the effects of short-term eccentric exercise training using a custom-made isokinetic leg press device, on concentric and eccentric strength and explosiveness as well as jumping performance. Nineteen healthy males were divided into an eccentric (ECC

The lipid profile of elite basketball and soccer athletes was evaluated and compared with that of inactive individuals. Total cholesterol (T-C), low and high density lipoprotein cholesterol (LDL-C and HDL-C), and triglyceride (TG) concentration were measured in the morning and after a soccer or a basketball match. All parameters of lipid profile measured at a fasted and resting state, except HDL-C, were lower in the athletes compared with the controls (p < 0.01). The soccer match resulted in a greater decrease in TG (78.3 ± 6.7 to 70.7 ± 6.3, p < 0.01), T-C (179.3 ± 10.7 to 171.6 ± 9.6, p < 0.01), LDL-C (110.9 ± 8.9 to 103.5 ± 7.5, p < 0.01) compared with the basketball match that resulted only in a decrease in LDL-C (126.8 ± 9.5 to 117.3 ± 9.1, p < 0.01) and an increase in HDL-C that was similar to that observed after the soccer match (9-12%). These findings support the beneficial effects of basketball and soccer on cardiovascular health. © 2013 © Taylor & Francis Group, LLC.

This study examined the effects of baseline flexibility and vertical jump ability on straight leg raise range of motion (ROM) and counter-movement jump performance (CMJ) following different volumes of stretching and potentiating exercises. ROM and CMJ were measured after two different warm-up protocols involving static stretching and potentiating exercises. Three groups of elite athletes (10 male, 14 female artistic gymnasts and 10 female rhythmic gymnasts) varying greatly in ROM and CMJ, performed two warm-up routines. One warm-up included short (15 s) static stretching followed by 5 tuck jumps, while the other included long static stretching (30 s) followed by 3x5 tuck jumps. ROM and CMJ were measured before, during and for 12 min after the two warm-up routines. Three-way ANOVA showed large differences between the three groups in baseline ROM and CMJ performance. A type of warm-up x time interaction was found for both ROM (p = 0.031) and CMJ (p = 0.016). However, all athletes, irrespective of group, responded in a similar fashion to the different warm-up protocols for both ROM and CMJ, as indicated from the lack of significant interactions for group (condition x group, time x group or condition x time x group). In the short warm-up protocol, ROM was not affected by stretching, while in the long warm-up protocol ROM increased by 5.9% ± 0.7% (p = 0.001) after stretching. Similarly, CMJ remained unchanged after the short warm-up protocol, but increased by 4.6 ± 0.9% (p = 0.012) 4 min after the long warmup protocol, despite the increased ROM. It is concluded that the initial levels of flexibility and CMJ performance do not alter the responses of elite gymnasts to warm-up protocols differing in stretching and potentiating exercise volumes. Furthermore, 3 sets of 5 tuck jumps result in a relatively large increase in CMJ performance despite an increase in flexibility in these highly-trained athletes. © Journal of Sports Science and Medicine.

This study investigated the effects of muscle action type during conditioning activity (half-squat) on subsequent vertical jump performance. Fourteen track and field athletes (relative half-squat of 2.3 ± 0.3 times their body weight) completed 4 main trials in a randomized and counterbalanced order 5-7 days apart: (a) concentric (CON) halfsquats: 7.5 ± 1.2 repetitions against 90% of 1 repetition maximum (1RM), (b) eccentric (ECC) half-squats: 9.3 ± 1.5 repetitions against 70% of 1RM, and (c) 3 sets of 3-second maximal isometric (ISO) half-squats, (d) a control (CTRL) trial, where subjects rested for 10 minutes. The number of repetitions in CON and ECC was adjusted so that the impulse of the vertical ground reaction force was similar to ISO. Countermovement vertical jump (CMJ) performance was evaluated for 21 minutes after each main trial. Countermovement vertical jump performance in ISO was higher than CTRL from the second to the 10th minute of recovery, whereas CMJ performance in ECC was higher than CTRL from the sixth and 10th minute of recovery. Analysis of the peak individual responses revealed an increase in CMJ performance compared with baseline only in ISO (3.06 1.2%; p = 0.045), whereas no significant increases were observed in ECC and CON. Peak CMJ performance for all subjects in ISO and ECC was achieved within 2-10 minutes after the conditioning muscle actions. Isometric were more effective than CON and ECC muscle actions in increasing explosive leg performance when the impulse of the ground reaction force of the conditioning exercise was equated. © 2014 National Strength and Conditioning Association.

{This study investigated the effects of short-term eccentric exercise training using a custom-made isokinetic leg press device, on concentric and eccentric strength and explosiveness as well as jumping performance. Nineteen healthy males were divided into an eccentric (ECC

The lipid profile of elite basketball and soccer athletes was evaluated and compared with that of inactive individuals. Total cholesterol (T-C), low and high density lipoprotein cholesterol (LDL-C and HDL-C), and triglyceride (TG) concentration were measured in the morning and after a soccer or a basketball match. All parameters of lipid profile measured at a fasted and resting state, except HDL-C, were lower in the athletes compared with the controls (p < 0.01). The soccer match resulted in a greater decrease in TG (78.3 ± 6.7 to 70.7 ± 6.3, p < 0.01), T-C (179.3 ± 10.7 to 171.6 ± 9.6, p < 0.01), LDL-C (110.9 ± 8.9 to 103.5 ± 7.5, p < 0.01) compared with the basketball match that resulted only in a decrease in LDL-C (126.8 ± 9.5 to 117.3 ± 9.1, p < 0.01) and an increase in HDL-C that was similar to that observed after the soccer match (9-12%). These findings support the beneficial effects of basketball and soccer on cardiovascular health. © 2013 © Taylor & Francis Group, LLC.

The purpose of the study was to compare bilateral deficit in jumping (i.e. when the sum of left and right leg jump height is greater than the two-leg jump) between pre-pubertal boys and girls. One hundred and seventy two children (83 boys and 89 girls between) were divided into two groups (10 and 12 years old) and performed oneleg and two-leg counter movement jumps without arm swing on a contact mat. The bilateral jump deficit index was calculated as: 1-(right+left leg jump height)/two-leg jump height x 100. Peak leg power output during jumping was also calculated and was scaled with body mass. Jump height and relative leg peak power were similar in boys and girls of both age groups. However, the bilateral jump deficit index was always greater and positive in boys compared with girls, indicating that the two-legged jump performance was better than the sum of right and left leg jumps. This difference between boys and girls remained even when training history was taken into account (trained vs. untrained children), indicating that it is independent of training status. Also, when differences in bilateral deficit were examined with analysis of covariance, with maturity offset (an index of biological maturation) as the covariate, boys still had greater values than girls (12.9±2.0 vs. -1.6±2.3%, p<0.01). In conclusion, the results of the present study indicated that the there was no bilateral deficit for vertical jumping for boys at this age range. In contrast, girls had a bilateral index that was close to zero, indicating equal two-leg and sum of two legs jumps. These differences between boys and girls may be explained by a reduced ability to activate motor units during pre-puberty and/or superior motor skill ability (i.e. balance on one leg and jump) of girls over boys at that age. © JPES.

High jumpers strive to maintain low body mass and may be at increased risk for inadequate nutrient intakes. Since there is no data on the nutritional status in this sport, this study aimed to evaluate the nutritional intake of elite high jumpers (7 males, 7 females). Athletes were in energy balance (energy intake was equal to energy expenditure and body mass was stable), but their energy intake was among the lowest reported for athletes (148±23 and 142±18 kJ/kg/day, for males and females). Carbohydrate intake of both males and females (3.6±0.8 g/kg/day) was low compared with recommended values, and diet was deficient in several micronutrients such as vitamin D (12% of dietary reference intake, DRI), vitamin E (34% DRI), folate (46% DRI), calcium (78% DRI) and iron (55% DRI, for females only). These low carbohydrate and micronutrient intakes may negatively affect training quality and adaptations and may jeopardize the athletes' health. © JPES.

This study investigated the changes in oxidative stress biomarkers and antioxidant status indices caused by a 3-week high-intensity interval training (HIT) regimen. Eight physically active males performed three HIT sessions/week over 3. weeks. Each session included four to six 30-s bouts of high-intensity cycling separated by 4. min of recovery. Before training, acute exercise elevated protein carbonyls (PC), thiobarbituric acid reactive substances (TBARS), glutathione peroxidase (GPX) activity, total antioxidant capacity (TAC) and creatine kinase (CK), which peaked 24. h post-exercise (252 ± 30%, 135 ± 17%, 10 ± 2%, 85 ± 14% and 36 ± 13%, above baseline, respectively; p<. 0.01), while catalase activity (CAT) peaked 30. min post-exercise (56 ± 18% above baseline; p<. 0.01). Training attenuated the exercise-induced increase in oxidative stress markers (PC by 13.3 ± 3.7%; TBARS by 7.2 ± 2.7%, p<. 0.01) and CK activity, despite the fact that total work done was 10.9 ± 3.6% greater in the post- compared with the pre-training exercise test. Training also induced a marked elevation of antioxidant status indices (TAC by 38.4 ± 7.2%; CAT by 26.2 ± 10.1%; GPX by 3.0 ± 0.6%, p<. 0.01). Short-term HIT attenuates oxidative stress and up-regulates antioxidant activity after only nine training sessions totaling 22. min of high intensity exercise, further supporting its positive effect not only on physical conditioning but also on health promotion. © 2013 Elsevier Ltd.

The purpose of the study was to compare bilateral deficit in jumping (i.e. when the sum of left and right leg jump height is greater than the two-leg jump) between pre-pubertal boys and girls. One hundred and seventy two children (83 boys and 89 girls between) were divided into two groups (10 and 12 years old) and performed oneleg and two-leg counter movement jumps without arm swing on a contact mat. The bilateral jump deficit index was calculated as: 1-(right+left leg jump height)/two-leg jump height x 100. Peak leg power output during jumping was also calculated and was scaled with body mass. Jump height and relative leg peak power were similar in boys and girls of both age groups. However, the bilateral jump deficit index was always greater and positive in boys compared with girls, indicating that the two-legged jump performance was better than the sum of right and left leg jumps. This difference between boys and girls remained even when training history was taken into account (trained vs. untrained children), indicating that it is independent of training status. Also, when differences in bilateral deficit were examined with analysis of covariance, with maturity offset (an index of biological maturation) as the covariate, boys still had greater values than girls (12.9±2.0 vs. -1.6±2.3%, p<0.01). In conclusion, the results of the present study indicated that the there was no bilateral deficit for vertical jumping for boys at this age range. In contrast, girls had a bilateral index that was close to zero, indicating equal two-leg and sum of two legs jumps. These differences between boys and girls may be explained by a reduced ability to activate motor units during pre-puberty and/or superior motor skill ability (i.e. balance on one leg and jump) of girls over boys at that age. © JPES.

High jumpers strive to maintain low body mass and may be at increased risk for inadequate nutrient intakes. Since there is no data on the nutritional status in this sport, this study aimed to evaluate the nutritional intake of elite high jumpers (7 males, 7 females). Athletes were in energy balance (energy intake was equal to energy expenditure and body mass was stable), but their energy intake was among the lowest reported for athletes (148±23 and 142±18 kJ/kg/day, for males and females). Carbohydrate intake of both males and females (3.6±0.8 g/kg/day) was low compared with recommended values, and diet was deficient in several micronutrients such as vitamin D (12% of dietary reference intake, DRI), vitamin E (34% DRI), folate (46% DRI), calcium (78% DRI) and iron (55% DRI, for females only). These low carbohydrate and micronutrient intakes may negatively affect training quality and adaptations and may jeopardize the athletes' health. © JPES.

This study investigated the changes in oxidative stress biomarkers and antioxidant status indices caused by a 3-week high-intensity interval training (HIT) regimen. Eight physically active males performed three HIT sessions/week over 3. weeks. Each session included four to six 30-s bouts of high-intensity cycling separated by 4. min of recovery. Before training, acute exercise elevated protein carbonyls (PC), thiobarbituric acid reactive substances (TBARS), glutathione peroxidase (GPX) activity, total antioxidant capacity (TAC) and creatine kinase (CK), which peaked 24. h post-exercise (252 ± 30%, 135 ± 17%, 10 ± 2%, 85 ± 14% and 36 ± 13%, above baseline, respectively; p<. 0.01), while catalase activity (CAT) peaked 30. min post-exercise (56 ± 18% above baseline; p<. 0.01). Training attenuated the exercise-induced increase in oxidative stress markers (PC by 13.3 ± 3.7%; TBARS by 7.2 ± 2.7%, p<. 0.01) and CK activity, despite the fact that total work done was 10.9 ± 3.6% greater in the post- compared with the pre-training exercise test. Training also induced a marked elevation of antioxidant status indices (TAC by 38.4 ± 7.2%; CAT by 26.2 ± 10.1%; GPX by 3.0 ± 0.6%, p<. 0.01). Short-term HIT attenuates oxidative stress and up-regulates antioxidant activity after only nine training sessions totaling 22. min of high intensity exercise, further supporting its positive effect not only on physical conditioning but also on health promotion. © 2013 Elsevier Ltd.

The purpose of the study was to compare bilateral deficit in jumping (i.e. when the sum of left and right leg jump height is greater than the two-leg jump) between pre-pubertal boys and girls. One hundred and seventy two children (83 boys and 89 girls between) were divided into two groups (10 and 12 years old) and performed oneleg and two-leg counter movement jumps without arm swing on a contact mat. The bilateral jump deficit index was calculated as: 1-(right+left leg jump height)/two-leg jump height x 100. Peak leg power output during jumping was also calculated and was scaled with body mass. Jump height and relative leg peak power were similar in boys and girls of both age groups. However, the bilateral jump deficit index was always greater and positive in boys compared with girls, indicating that the two-legged jump performance was better than the sum of right and left leg jumps. This difference between boys and girls remained even when training history was taken into account (trained vs. untrained children), indicating that it is independent of training status. Also, when differences in bilateral deficit were examined with analysis of covariance, with maturity offset (an index of biological maturation) as the covariate, boys still had greater values than girls (12.9±2.0 vs. -1.6±2.3%, p<0.01). In conclusion, the results of the present study indicated that the there was no bilateral deficit for vertical jumping for boys at this age range. In contrast, girls had a bilateral index that was close to zero, indicating equal two-leg and sum of two legs jumps. These differences between boys and girls may be explained by a reduced ability to activate motor units during pre-puberty and/or superior motor skill ability (i.e. balance on one leg and jump) of girls over boys at that age. © JPES.

High jumpers strive to maintain low body mass and may be at increased risk for inadequate nutrient intakes. Since there is no data on the nutritional status in this sport, this study aimed to evaluate the nutritional intake of elite high jumpers (7 males, 7 females). Athletes were in energy balance (energy intake was equal to energy expenditure and body mass was stable), but their energy intake was among the lowest reported for athletes (148±23 and 142±18 kJ/kg/day, for males and females). Carbohydrate intake of both males and females (3.6±0.8 g/kg/day) was low compared with recommended values, and diet was deficient in several micronutrients such as vitamin D (12% of dietary reference intake, DRI), vitamin E (34% DRI), folate (46% DRI), calcium (78% DRI) and iron (55% DRI, for females only). These low carbohydrate and micronutrient intakes may negatively affect training quality and adaptations and may jeopardize the athletes' health. © JPES.

This study investigated the changes in oxidative stress biomarkers and antioxidant status indices caused by a 3-week high-intensity interval training (HIT) regimen. Eight physically active males performed three HIT sessions/week over 3. weeks. Each session included four to six 30-s bouts of high-intensity cycling separated by 4. min of recovery. Before training, acute exercise elevated protein carbonyls (PC), thiobarbituric acid reactive substances (TBARS), glutathione peroxidase (GPX) activity, total antioxidant capacity (TAC) and creatine kinase (CK), which peaked 24. h post-exercise (252 ± 30%, 135 ± 17%, 10 ± 2%, 85 ± 14% and 36 ± 13%, above baseline, respectively; p<. 0.01), while catalase activity (CAT) peaked 30. min post-exercise (56 ± 18% above baseline; p<. 0.01). Training attenuated the exercise-induced increase in oxidative stress markers (PC by 13.3 ± 3.7%; TBARS by 7.2 ± 2.7%, p<. 0.01) and CK activity, despite the fact that total work done was 10.9 ± 3.6% greater in the post- compared with the pre-training exercise test. Training also induced a marked elevation of antioxidant status indices (TAC by 38.4 ± 7.2%; CAT by 26.2 ± 10.1%; GPX by 3.0 ± 0.6%, p<. 0.01). Short-term HIT attenuates oxidative stress and up-regulates antioxidant activity after only nine training sessions totaling 22. min of high intensity exercise, further supporting its positive effect not only on physical conditioning but also on health promotion. © 2013 Elsevier Ltd.

This study examined the effects of two different warm-up protocols on lower limb power and flexibility in high level athletes. Twenty international level fencers (10 males and 10 females) performed two warm-up protocols that included 5-min light jogging and either short (15s) or long (45s) static stretching exercises for each of the main leg muscle groups (quadriceps, hamstrings and triceps surae), followed by either 3 sets of 3 (short stretching treatment), or 3 sets of 5 tuck jumps (long stretching treatment), in a randomized crossover design with one week between treatments. Hip joint flexion was measured with a Lafayette goniometer before and after the 5-min warm-up, after stretching and 8 min after the tuck jumps, while counter movement jump (CMJ) performance was evaluated by an Ergojump contact platform, before and after the stretching treatment, as well as immediately after and 8 minutes after the tuck jumps. Three way ANOVA (condition, time, gender) revealed significant time (p < 0.001) and gender (p < 0.001) main effects for hip joint flexion, with no interaction between factors. Flexibility increased by 6.8 ± 1.1% (p < 0.01) after warm-up and by another 5.8 ± 1.6% (p < 0.01) after stretching, while it remained increased 8 min after the tuck jumps. Women had greater ROM compared with men at all time points (125 ± 8° vs. 94 ± 4° p<0.01 at baseline), but the pattern of change in hip flexibility was not different between genders. CMJ performance was greater in men compared with women at all time points (38.2 ± 1.9 cm vs. 29.8 ± 1.2 cm p < 0.01 at baseline), but the percentage of change CMJ performance was not different between genders. CMJ performance remained unchanged throughout the short stretching protocol, while it decreased by 5.5±0.9% (p <0.01) after stretching in the long stretching protocol However, 8 min after the tuck jumps, CMJ performance was not different from the baseline value (p = 0.075). In conclusion, lower limb power may be decreased after long periods of stretching, but performance of explosive exercises may reverse this phenomenon. © Journal of Sports Science and Medicine.

This study examined the effects of two different warm-up protocols on lower limb power and flexibility in high level athletes. Twenty international level fencers (10 males and 10 females) performed two warm-up protocols that included 5-min light jogging and either short (15s) or long (45s) static stretching exercises for each of the main leg muscle groups (quadriceps, hamstrings and triceps surae), followed by either 3 sets of 3 (short stretching treatment), or 3 sets of 5 tuck jumps (long stretching treatment), in a randomized crossover design with one week between treatments. Hip joint flexion was measured with a Lafayette goniometer before and after the 5-min warm-up, after stretching and 8 min after the tuck jumps, while counter movement jump (CMJ) performance was evaluated by an Ergojump contact platform, before and after the stretching treatment, as well as immediately after and 8 minutes after the tuck jumps. Three way ANOVA (condition, time, gender) revealed significant time (p < 0.001) and gender (p < 0.001) main effects for hip joint flexion, with no interaction between factors. Flexibility increased by 6.8 ± 1.1% (p < 0.01) after warm-up and by another 5.8 ± 1.6% (p < 0.01) after stretching, while it remained increased 8 min after the tuck jumps. Women had greater ROM compared with men at all time points (125 ± 8° vs. 94 ± 4° p<0.01 at baseline), but the pattern of change in hip flexibility was not different between genders. CMJ performance was greater in men compared with women at all time points (38.2 ± 1.9 cm vs. 29.8 ± 1.2 cm p < 0.01 at baseline), but the percentage of change CMJ performance was not different between genders. CMJ performance remained unchanged throughout the short stretching protocol, while it decreased by 5.5±0.9% (p <0.01) after stretching in the long stretching protocol However, 8 min after the tuck jumps, CMJ performance was not different from the baseline value (p = 0.075). In conclusion, lower limb power may be decreased after long periods of stretching, but performance of explosive exercises may reverse this phenomenon. © Journal of Sports Science and Medicine.

The aim of this review was to examine the mechanisms by which physical activity and inactivity modify muscle fatigue. It is well known that acute or chronic increases in physical activity result in structural, metabolic, hormonal, neural, and molecular adaptations that increase the level of force or power that can be sustained by a muscle. These adaptations depend on the type, intensity, and volume of the exercise stimulus, but recent studies have highlighted the role of high intensity, short-duration exercise as a time-efficient method to achieve both anaerobic and aerobic/endurance type adaptations.The factors that determine the fatigue profile of a muscle during intense exercise include muscle fiber composition, neuromuscular characteristics, high energy metabolite stores, buffering capacity, ionic regulation, capillarization, and mitochondrial density. Muscle fiber-type transformation during exercise training is usually toward the intermediate type IIA at the expense of both type I and IIx myosin heavy-chain isoforms. High-intensity training results in increases of both glycolytic and oxidative enzymes, muscle capillarization, improved phosphocreatine resynthesis and regulation of K +, H +, and lactate ions. Decreases of the habitual activity level due to injury or sedentary lifestyle result in partial or even compete reversal of the adaptations due to previous training, manifested by reductions in fiber cross-sectional area, decreased oxidative capacity, and capillarization. Complete immobilization due to injury results in markedly decreased force output and fatigue resistance. Muscle unloading reduces electromyographic activity and causes muscle atrophy and significant decreases in capillarization and oxidative enzymes activity. The last part of the review discusses the beneficial effects of intermittent high-intensity exercise training in patients with different health conditions to demonstrate the powerful effect of exercise on health and well being. © 2012 Bogdanis.

This study examined the effects of two different warm-up protocols on lower limb power and flexibility in high level athletes. Twenty international level fencers (10 males and 10 females) performed two warm-up protocols that included 5-min light jogging and either short (15s) or long (45s) static stretching exercises for each of the main leg muscle groups (quadriceps, hamstrings and triceps surae), followed by either 3 sets of 3 (short stretching treatment), or 3 sets of 5 tuck jumps (long stretching treatment), in a randomized crossover design with one week between treatments. Hip joint flexion was measured with a Lafayette goniometer before and after the 5-min warm-up, after stretching and 8 min after the tuck jumps, while counter movement jump (CMJ) performance was evaluated by an Ergojump contact platform, before and after the stretching treatment, as well as immediately after and 8 minutes after the tuck jumps. Three way ANOVA (condition, time, gender) revealed significant time (p < 0.001) and gender (p < 0.001) main effects for hip joint flexion, with no interaction between factors. Flexibility increased by 6.8 ± 1.1% (p < 0.01) after warm-up and by another 5.8 ± 1.6% (p < 0.01) after stretching, while it remained increased 8 min after the tuck jumps. Women had greater ROM compared with men at all time points (125 ± 8° vs. 94 ± 4° p<0.01 at baseline), but the pattern of change in hip flexibility was not different between genders. CMJ performance was greater in men compared with women at all time points (38.2 ± 1.9 cm vs. 29.8 ± 1.2 cm p < 0.01 at baseline), but the percentage of change CMJ performance was not different between genders. CMJ performance remained unchanged throughout the short stretching protocol, while it decreased by 5.5±0.9% (p <0.01) after stretching in the long stretching protocol However, 8 min after the tuck jumps, CMJ performance was not different from the baseline value (p = 0.075). In conclusion, lower limb power may be decreased after long periods of stretching, but performance of explosive exercises may reverse this phenomenon. © Journal of Sports Science and Medicine.

The aim of the present study was to evaluate the levels of homocysteine and 8-iso PGF2a in football and hockey players before and soon after a match, on the predisposition for development of atherosclerosis. We measured 8-iso-PGF2a and homocysteine in 21 football athletes aged 21.8 ± 3.7 years old and 18 hockey athletes 22.2 ± 3.3 years old, respectively. All the athletes presented significant increases in serum homocysteine levels following the match (p = 0.001 for football and p = 0.001 for hockey players) Also a statistically significant increase of 8-iso-PGF 2a levels was found in hockey and football athletes following the match (p < 0.001 and p = 0.071). Our findings suggest that strenuous exercise such as a football or a hockey match causes a marked increase in serum homocysteine and 8-iso-PGF2a. Due to the fact that homocysteine and 8-iso-PGF2a are contributing to atheromatosis, it may be useful to follow a restoration exercise program that involves mild exercise and to pay special attention to folate, vitamin B6, and vitamin B12 balance during the first 24 h after the match. Copyright © Taylor & Francis Group, LLC.

This study compared the effects of two different half-squat training programs on the repeated-sprint ability of soccer players during the preseason. Twenty male professional soccer players were divided into 2 groups: One group (S-group) performed 4 sets of 5 repetitions with 90% of their 1-repetition maximum (1RM), and the other group (H-group) performed 4 sets of 12 repetitions with 70% of 1RM, 3 times per week for 6 weeks, in addition to their common preseason training program. Repeated-sprint ability was assessed before and after training by 10 × 6-second cycle ergometer sprints separated by 24 seconds of passive recovery. Maximal halfsquat strength increased significantly in both groups (p < 0.01), but this increase was significantly greater in the S-group compared with the H-group (17.3 ± 1.9 vs. 11.0 ± 1.9%, p < 0.05). Lean leg volume (LLV) increased only in the H-group. Total work over the 10 sprints improved in both groups after training, but this increase was significantly greater in the second half (8.9 ± 2.6%) compared with the first half of the sprint test (3.2 ± 1.7%) only in the S-group. Mean power output (MPO) expressed per liter of LLV was better maintained during the last 6 sprints posttraining only in the S-group, whereas there was no change in MPO per LLV in the H-group over the 10 sprints. These results suggest that resistance training with high loads is superior to a moderate-load program, because it increases strength without a change in muscle mass and also results in a greater improvement in repeated sprint ability. Therefore, resistance training with high loads may be preferable when the aim is to improve maximal strength and fatigue during sprinting in professional soccer players. © 2011 National Strength and Conditioning Association.

The purpose of this study was to evaluate the postactivation potentiation (PAP) effect of isometric and plyometric contractions on explosive performance of the upper and the lower limbs in male and female elite athletes. Thirteen male and ten female international level fencers performed four protocols of either isometric (3 sets of 3 sec) or plyometric (3 sets of 5 repetitions) bench and leg press, in a within subject randomized design. Before and immediately after the PAP treatment and following 4, 8, 12 min, explosive performance was measured by performing a countermovement jump (CMJ) or a bench press throw. Statistical analysis revealed significant time effect for peak leg power during the CMJ (p < 0.001) only for men, with values after the isometric PAP treatment being lower than baseline at the 8 and 12 min time points (by 7.5% (CI95% = 3.9-11.2%) and 8.7% (CI95% = 6.0-11.5%, respectively), while after the plyometric PAP treatment peak leg power remained unchanged. A significant negative correlation was found between leg strength (as expressed by 1-RM leg press performance) and the change in peak leg power between baseline and after 12 min of recovery only in male fencers (r = -0.55, p < 0.05), suggesting that stronger individuals may show a greater decrease in peak leg power. Based on the above results we conclude that lower body power performance in international level fencers may be negatively affected after isometric contractions and thus they should be advised against using isometric exercises to induce PAP with the protocol prescribed in the present study. Furthermore, gender and strength level must be considered in the practical application of PAP. © Journal of Sports Science and Medicine.

Repeated-sprint training often involves short sprints separated by inadequate recovery intervals. The effects of interval duration on metabolic and performance parameters are unclear. We compared the effects of two training programmes, differing in rest interval duration, on muscle (vastus lateralis) metabolism and sprint performance. Sixteen men trained three times a week for 8 weeks, each training session comprising 2-3 sets of two 80-m sprints. Sprints were separated by 10 s (n = 8) or 1 min (n = 8). Both training programmes improved performance in the 100-, 200-, and 300-m sprints, but the improvement was greater in the 10-s group during the final 100 m of the 200- and 300-m runs. Independent of interval duration, training mitigated the drop of muscle ATP after two 80-m sprints. The drop in phosphocreatine and the increases in glucose-6-phosphate and fructose-6-phosphate after two 80-m sprints were greater in the 10-s group. In conclusion, training with a limited number of repeated short sprints (≤10 s) may be more effective in improving speed maintenance in 200- and 300-m runs when performed with a 1:1 rather than a 1:6 exercise-to-rest ratio. This may be due to a greater activation of glycolysis caused, in part, by the limited resynthesis of phosphocreatine during the very short rest interval. © 2011 Taylor & Francis.

The aim of the present study was to evaluate the levels of homocysteine and 8-iso PGF2a in football and hockey players before and soon after a match, on the predisposition for development of atherosclerosis. We measured 8-iso-PGF2a and homocysteine in 21 football athletes aged 21.8 ± 3.7 years old and 18 hockey athletes 22.2 ± 3.3 years old, respectively. All the athletes presented significant increases in serum homocysteine levels following the match (p = 0.001 for football and p = 0.001 for hockey players) Also a statistically significant increase of 8-iso-PGF 2a levels was found in hockey and football athletes following the match (p < 0.001 and p = 0.071). Our findings suggest that strenuous exercise such as a football or a hockey match causes a marked increase in serum homocysteine and 8-iso-PGF2a. Due to the fact that homocysteine and 8-iso-PGF2a are contributing to atheromatosis, it may be useful to follow a restoration exercise program that involves mild exercise and to pay special attention to folate, vitamin B6, and vitamin B12 balance during the first 24 h after the match. Copyright © Taylor & Francis Group, LLC.

This study compared the effects of two different half-squat training programs on the repeated-sprint ability of soccer players during the preseason. Twenty male professional soccer players were divided into 2 groups: One group (S-group) performed 4 sets of 5 repetitions with 90% of their 1-repetition maximum (1RM), and the other group (H-group) performed 4 sets of 12 repetitions with 70% of 1RM, 3 times per week for 6 weeks, in addition to their common preseason training program. Repeated-sprint ability was assessed before and after training by 10 × 6-second cycle ergometer sprints separated by 24 seconds of passive recovery. Maximal halfsquat strength increased significantly in both groups (p < 0.01), but this increase was significantly greater in the S-group compared with the H-group (17.3 ± 1.9 vs. 11.0 ± 1.9%, p < 0.05). Lean leg volume (LLV) increased only in the H-group. Total work over the 10 sprints improved in both groups after training, but this increase was significantly greater in the second half (8.9 ± 2.6%) compared with the first half of the sprint test (3.2 ± 1.7%) only in the S-group. Mean power output (MPO) expressed per liter of LLV was better maintained during the last 6 sprints posttraining only in the S-group, whereas there was no change in MPO per LLV in the H-group over the 10 sprints. These results suggest that resistance training with high loads is superior to a moderate-load program, because it increases strength without a change in muscle mass and also results in a greater improvement in repeated sprint ability. Therefore, resistance training with high loads may be preferable when the aim is to improve maximal strength and fatigue during sprinting in professional soccer players. © 2011 National Strength and Conditioning Association.

The purpose of this study was to evaluate the postactivation potentiation (PAP) effect of isometric and plyometric contractions on explosive performance of the upper and the lower limbs in male and female elite athletes. Thirteen male and ten female international level fencers performed four protocols of either isometric (3 sets of 3 sec) or plyometric (3 sets of 5 repetitions) bench and leg press, in a within subject randomized design. Before and immediately after the PAP treatment and following 4, 8, 12 min, explosive performance was measured by performing a countermovement jump (CMJ) or a bench press throw. Statistical analysis revealed significant time effect for peak leg power during the CMJ (p < 0.001) only for men, with values after the isometric PAP treatment being lower than baseline at the 8 and 12 min time points (by 7.5% (CI95% = 3.9-11.2%) and 8.7% (CI95% = 6.0-11.5%, respectively), while after the plyometric PAP treatment peak leg power remained unchanged. A significant negative correlation was found between leg strength (as expressed by 1-RM leg press performance) and the change in peak leg power between baseline and after 12 min of recovery only in male fencers (r = -0.55, p < 0.05), suggesting that stronger individuals may show a greater decrease in peak leg power. Based on the above results we conclude that lower body power performance in international level fencers may be negatively affected after isometric contractions and thus they should be advised against using isometric exercises to induce PAP with the protocol prescribed in the present study. Furthermore, gender and strength level must be considered in the practical application of PAP. © Journal of Sports Science and Medicine.

Repeated-sprint training often involves short sprints separated by inadequate recovery intervals. The effects of interval duration on metabolic and performance parameters are unclear. We compared the effects of two training programmes, differing in rest interval duration, on muscle (vastus lateralis) metabolism and sprint performance. Sixteen men trained three times a week for 8 weeks, each training session comprising 2-3 sets of two 80-m sprints. Sprints were separated by 10 s (n = 8) or 1 min (n = 8). Both training programmes improved performance in the 100-, 200-, and 300-m sprints, but the improvement was greater in the 10-s group during the final 100 m of the 200- and 300-m runs. Independent of interval duration, training mitigated the drop of muscle ATP after two 80-m sprints. The drop in phosphocreatine and the increases in glucose-6-phosphate and fructose-6-phosphate after two 80-m sprints were greater in the 10-s group. In conclusion, training with a limited number of repeated short sprints (≤10 s) may be more effective in improving speed maintenance in 200- and 300-m runs when performed with a 1:1 rather than a 1:6 exercise-to-rest ratio. This may be due to a greater activation of glycolysis caused, in part, by the limited resynthesis of phosphocreatine during the very short rest interval. © 2011 Taylor & Francis.

The aim of the present study was to evaluate the levels of homocysteine and 8-iso PGF 2a in football and hockey players before and soon after a match, on the predisposition for development of atherosclerosis. We measured 8-iso-PGF 2a and homocysteine in 21 football athletes aged 21.8 ± 3.7 years old and 18 hockey athletes 22.2 ± 3.3 years old, respectively. All the athletes presented significant increases in serum homocysteine levels following the match (p = 0.001 for football and p = 0.001 for hockey players) Also a statistically significant increase of 8-iso-PGF 2a levels was found in hockey and football athletes following the match (p < 0.001 and p = 0.071). Our findings suggest that strenuous exercise such as a football or a hockey match causes a marked increase in serum homocysteine and 8-iso-PGF 2a. Due to the fact that homocysteine and 8-iso-PGF 2a are contributing to atheromatosis, it may be useful to follow a restoration exercise program that involves mild exercise and to pay special attention to folate, vitamin B6, and vitamin B12 balance during the first 24 h after the match. Copyright © Taylor & Francis Group, LLC.

This study compared the effects of two different half-squat training programs on the repeated-sprint ability of soccer players during the preseason. Twenty male professional soccer players were divided into 2 groups: One group (S-group) performed 4 sets of 5 repetitions with 90% of their 1-repetition maximum (1RM), and the other group (H-group) performed 4 sets of 12 repetitions with 70% of 1RM, 3 times per week for 6 weeks, in addition to their common preseason training program. Repeated-sprint ability was assessed before and after training by 10 × 6-second cycle ergometer sprints separated by 24 seconds of passive recovery. Maximal halfsquat strength increased significantly in both groups (p < 0.01), but this increase was significantly greater in the S-group compared with the H-group (17.3 ± 1.9 vs. 11.0 ± 1.9%, p < 0.05). Lean leg volume (LLV) increased only in the H-group. Total work over the 10 sprints improved in both groups after training, but this increase was significantly greater in the second half (8.9 ± 2.6%) compared with the first half of the sprint test (3.2 ± 1.7%) only in the S-group. Mean power output (MPO) expressed per liter of LLV was better maintained during the last 6 sprints posttraining only in the S-group, whereas there was no change in MPO per LLV in the H-group over the 10 sprints. These results suggest that resistance training with high loads is superior to a moderate-load program, because it increases strength without a change in muscle mass and also results in a greater improvement in repeated sprint ability. Therefore, resistance training with high loads may be preferable when the aim is to improve maximal strength and fatigue during sprinting in professional soccer players. © 2011 National Strength and Conditioning Association.

The purpose of this study was to evaluate the postactivation potentiation (PAP) effect of isometric and plyometric contractions on explosive performance of the upper and the lower limbs in male and female elite athletes. Thirteen male and ten female international level fencers performed four protocols of either isometric (3 sets of 3 sec) or plyometric (3 sets of 5 repetitions) bench and leg press, in a within subject randomized design. Before and immediately after the PAP treatment and following 4, 8, 12 min, explosive performance was measured by performing a countermovement jump (CMJ) or a bench press throw. Statistical analysis revealed significant time effect for peak leg power during the CMJ (p < 0.001) only for men, with values after the isometric PAP treatment being lower than baseline at the 8 and 12 min time points (by 7.5% (CI95% = 3.9-11.2%) and 8.7% (CI95% = 6.0-11.5%, respectively), while after the plyometric PAP treatment peak leg power remained unchanged. A significant negative correlation was found between leg strength (as expressed by 1-RM leg press performance) and the change in peak leg power between baseline and after 12 min of recovery only in male fencers (r = -0.55, p < 0.05), suggesting that stronger individuals may show a greater decrease in peak leg power. Based on the above results we conclude that lower body power performance in international level fencers may be negatively affected after isometric contractions and thus they should be advised against using isometric exercises to induce PAP with the protocol prescribed in the present study. Furthermore, gender and strength level must be considered in the practical application of PAP. © Journal of Sports Science and Medicine.

Repeated-sprint training often involves short sprints separated by inadequate recovery intervals. The effects of interval duration on metabolic and performance parameters are unclear. We compared the effects of two training programmes, differing in rest interval duration, on muscle (vastus lateralis) metabolism and sprint performance. Sixteen men trained three times a week for 8 weeks, each training session comprising 2-3 sets of two 80-m sprints. Sprints were separated by 10 s (n = 8) or 1 min (n = 8). Both training programmes improved performance in the 100-, 200-, and 300-m sprints, but the improvement was greater in the 10-s group during the final 100 m of the 200- and 300-m runs. Independent of interval duration, training mitigated the drop of muscle ATP after two 80-m sprints. The drop in phosphocreatine and the increases in glucose-6-phosphate and fructose-6-phosphate after two 80-m sprints were greater in the 10-s group. In conclusion, training with a limited number of repeated short sprints (≤10 s) may be more effective in improving speed maintenance in 200- and 300-m runs when performed with a 1:1 rather than a 1:6 exercise-to-rest ratio. This may be due to a greater activation of glycolysis caused, in part, by the limited resynthesis of phosphocreatine during the very short rest interval. © 2011 Taylor & Francis.

The effect of resistance exercise on blood lipids is not clear yet. The purpose of this study was to examine the cholesterol responses to a heavy resistance leg press exercise emphasizing on the eccentric movement 24 and 48 hours following exercise and to quantify the cardiorespiratory responses of the exercise bout in an attempt to clarify the exercise characteristics that may be responsible for the effects of heavy resistance exercise on blood lipids. Nine healthy, untrained male volunteers aged 27.2 ± 1.1 yrs (76.2 ± 2.5 kg, 1.79 ± 0.02 m) performed a session of heavy RE emphasizing on the eccentric movement consisting of eight sets of inclined leg presses at six repetition maximum with 3-min rest intervals. Venous blood samples were obtained at rest (control) and 24 and 48 hours following exercise. Average VO2 at rest was 4.0 ± 0.4 ml·min-1·kg-1, during exercise 19.6 ± 0.2 ml·min-1·kg-1 and during the 180 sec recovery period between sets 12.5 ± 0.2 ml·min-1·kg-1. RER values decreased with the progression of the exercise and were significantly lower during the last four sets compared with the first four sets of the exercise session. Resting heart rate was 67 ± 2 bpm, and maximum heart rate during exercise was 168 ± 1 bspm. Serum creatine kinase was significantly elevated on day 1 (1090 ± 272 U·L-1, p < 0.03) and peaked on day 2 (1230 ± 440 U·L-1 p < 0.01). Total cholesterol, HDL cholesterol and calculated LDL cholesterol concentration did not change significantly following with exercise. This protocol of heavy resistance exercise has no effect on TC or cholesterol sub-fraction concentration 24 and 48 hours following exercise which may be due to the low energy expenditure of the exercise and/or to the gender of the participants. © Journal of Sports Science and Medicine.

{Aim. Intense and prolonged exercise greatly affects circulating cytokine levels. The purpose of this study was to investigate the possible changes in tumour necrosis factor -a (TNF-a), interleukin 6 (IL-6) and Cortisol concentrations during and after prolonged exercise of constant and alternating intensity of the same duration and total work performed. Methods. Ten male subjects underwent two main cycling exercise trials lasting one hour each. On one occasion, exercise intensity was alternated between 46.5±1.9% of maximal oxygen uptake (VO2max ) for 40 s and 120% of VO2max for 20 s, so that the mean intensity corresponded to 105% of the lactate threshold. On the other occasion, exercise intensity was constant at 105% of the lactate threshold. Levels of TNF-a, IL-6 after lipo polysaccharide (LPS) stimulation as well as Cortisol were measured at rest, 30 and 60 minutes of exercise and 1 hour after. Results. No significant differences were observed in TNF-a concentrations between the two exercise protocols (P= 0.75), but there was a significant time effect (P<0.01). TNF-a was increased in both groups from a resting value of 436.1±102.5 to 649.5±187.7 pg/mL (P<0.05) at the end of exercise and was subsequently decreased 1 hour post exercise to 305.9±78.8 pg/mL (P<0.01). No significant difference in IL-6 and Cortisol concentrations was observed between the two exercise protocols (P=0.13

Eccentric exercise has been extensively used as a model to study muscle damage-induced neuromuscular impairment, adopting mainly a bilateral matching task between the reference (unexercised) arm and the indicator (exercised) arm. However, little attention has been given to the muscle proprioceptive function when the exercised arm acts as its own reference. This study investigated muscle proprioception and motor control, with the arm acting both as reference and indicator, following eccentric exercise and compared them with those observed after isometric exercise. Fourteen young male volunteers were equally divided into two groups and performed an eccentric or isometric exercise protocol with the elbow flexors of the non-dominant arm on an isokinetic dynamometer. Both exercise protocols induced significant changes in indicators of muscle damage, that is, muscle soreness, range of motion and maximal isometric force post-exercise (p < 0.050.001), and neuromuscular function was similarly affected following both protocols. Perception of force was impaired over the 4-day post-exercise period (p < 0.001), with the applied force being systematically overestimated. Perception of joint position was significantly disturbed (i.e., target angle was underestimated) only at one elbow angle on day 4 post-exercise (p < 0.05). The misjudgements and disturbed motor output observed when the exercised arm acted as its own reference concur with the view that they could be a result of a mismatch between the central motor command and an impaired motor control after muscle damage. © 2010 Informa Healthcare Ltd.

The effect of resistance exercise on blood lipids is not clear yet. The purpose of this study was to examine the cholesterol responses to a heavy resistance leg press exercise emphasizing on the eccentric movement 24 and 48 hours following exercise and to quantify the cardiorespiratory responses of the exercise bout in an attempt to clarify the exercise characteristics that may be responsible for the effects of heavy resistance exercise on blood lipids. Nine healthy, untrained male volunteers aged 27.2 ± 1.1 yrs (76.2 ± 2.5 kg, 1.79 ± 0.02 m) performed a session of heavy RE emphasizing on the eccentric movement consisting of eight sets of inclined leg presses at six repetition maximum with 3-min rest intervals. Venous blood samples were obtained at rest (control) and 24 and 48 hours following exercise. Average VO2 at rest was 4.0 ± 0.4 ml·min-1·kg-1, during exercise 19.6 ± 0.2 ml·min-1·kg-1 and during the 180 sec recovery period between sets 12.5 ± 0.2 ml·min-1·kg-1. RER values decreased with the progression of the exercise and were significantly lower during the last four sets compared with the first four sets of the exercise session. Resting heart rate was 67 ± 2 bpm, and maximum heart rate during exercise was 168 ± 1 bspm. Serum creatine kinase was significantly elevated on day 1 (1090 ± 272 U·L-1, p < 0.03) and peaked on day 2 (1230 ± 440 U·L-1 p < 0.01). Total cholesterol, HDL cholesterol and calculated LDL cholesterol concentration did not change significantly following with exercise. This protocol of heavy resistance exercise has no effect on TC or cholesterol sub-fraction concentration 24 and 48 hours following exercise which may be due to the low energy expenditure of the exercise and/or to the gender of the participants. © Journal of Sports Science and Medicine.

{Aim. Intense and prolonged exercise greatly affects circulating cytokine levels. The purpose of this study was to investigate the possible changes in tumour necrosis factor -a (TNF-a), interleukin 6 (IL-6) and Cortisol concentrations during and after prolonged exercise of constant and alternating intensity of the same duration and total work performed. Methods. Ten male subjects underwent two main cycling exercise trials lasting one hour each. On one occasion, exercise intensity was alternated between 46.5±1.9% of maximal oxygen uptake (VO2max ) for 40 s and 120% of VO2max for 20 s, so that the mean intensity corresponded to 105% of the lactate threshold. On the other occasion, exercise intensity was constant at 105% of the lactate threshold. Levels of TNF-a, IL-6 after lipo polysaccharide (LPS) stimulation as well as Cortisol were measured at rest, 30 and 60 minutes of exercise and 1 hour after. Results. No significant differences were observed in TNF-a concentrations between the two exercise protocols (P= 0.75), but there was a significant time effect (P<0.01). TNF-a was increased in both groups from a resting value of 436.1±102.5 to 649.5±187.7 pg/mL (P<0.05) at the end of exercise and was subsequently decreased 1 hour post exercise to 305.9±78.8 pg/mL (P<0.01). No significant difference in IL-6 and Cortisol concentrations was observed between the two exercise protocols (P=0.13

Eccentric exercise has been extensively used as a model to study muscle damage-induced neuromuscular impairment, adopting mainly a bilateral matching task between the reference (unexercised) arm and the indicator (exercised) arm. However, little attention has been given to the muscle proprioceptive function when the exercised arm acts as its own reference. This study investigated muscle proprioception and motor control, with the arm acting both as reference and indicator, following eccentric exercise and compared them with those observed after isometric exercise. Fourteen young male volunteers were equally divided into two groups and performed an eccentric or isometric exercise protocol with the elbow flexors of the non-dominant arm on an isokinetic dynamometer. Both exercise protocols induced significant changes in indicators of muscle damage, that is, muscle soreness, range of motion and maximal isometric force post-exercise (p < 0.050.001), and neuromuscular function was similarly affected following both protocols. Perception of force was impaired over the 4-day post-exercise period (p < 0.001), with the applied force being systematically overestimated. Perception of joint position was significantly disturbed (i.e., target angle was underestimated) only at one elbow angle on day 4 post-exercise (p < 0.05). The misjudgements and disturbed motor output observed when the exercised arm acted as its own reference concur with the view that they could be a result of a mismatch between the central motor command and an impaired motor control after muscle damage. © 2010 Informa Healthcare Ltd.

The effect of resistance exercise on blood lipids is not clear yet. The purpose of this study was to examine the cholesterol responses to a heavy resistance leg press exercise emphasizing on the eccentric movement 24 and 48 hours following exercise and to quantify the cardiorespiratory responses of the exercise bout in an attempt to clarify the exercise characteristics that may be responsible for the effects of heavy resistance exercise on blood lipids. Nine healthy, untrained male volunteers aged 27.2 ± 1.1 yrs (76.2 ± 2.5 kg, 1.79 ± 0.02 m) performed a session of heavy RE emphasizing on the eccentric movement consisting of eight sets of inclined leg presses at six repetition maximum with 3-min rest intervals. Venous blood samples were obtained at rest (control) and 24 and 48 hours following exercise. Average VO2 at rest was 4.0 ± 0.4 ml·min-1·kg-1, during exercise 19.6 ± 0.2 ml·min-1·kg-1 and during the 180 sec recovery period between sets 12.5 ± 0.2 ml·min-1·kg-1. RER values decreased with the progression of the exercise and were significantly lower during the last four sets compared with the first four sets of the exercise session. Resting heart rate was 67 ± 2 bpm, and maximum heart rate during exercise was 168 ± 1 bspm. Serum creatine kinase was significantly elevated on day 1 (1090 ± 272 U·L-1, p < 0.03) and peaked on day 2 (1230 ± 440 U·L-1 p < 0.01). Total cholesterol, HDL cholesterol and calculated LDL cholesterol concentration did not change significantly following with exercise. This protocol of heavy resistance exercise has no effect on TC or cholesterol sub-fraction concentration 24 and 48 hours following exercise which may be due to the low energy expenditure of the exercise and/or to the gender of the participants. © Journal of Sports Science and Medicine.

Aim. Intense and prolonged exercise greatly affects circulating cytokine levels. The purpose of this study was to investigate the possible changes in tumour necrosis factor -a (TNF-a), interleukin 6 (IL-6) and Cortisol concentrations during and after prolonged exercise of constant and alternating intensity of the same duration and total work performed. Methods. Ten male subjects underwent two main cycling exercise trials lasting one hour each. On one occasion, exercise intensity was alternated between 46.5±1.9% of maximal oxygen uptake (VO2max ) for 40 s and 120% of VO2max for 20 s, so that the mean intensity corresponded to 105% of the lactate threshold. On the other occasion, exercise intensity was constant at 105% of the lactate threshold. Levels of TNF-a, IL-6 after lipo polysaccharide (LPS) stimulation as well as Cortisol were measured at rest, 30 and 60 minutes of exercise and 1 hour after. Results. No significant differences were observed in TNF-a concentrations between the two exercise protocols (P= 0.75), but there was a significant time effect (P<0.01). TNF-a was increased in both groups from a resting value of 436.1±102.5 to 649.5±187.7 pg/mL (P<0.05) at the end of exercise and was subsequently decreased 1 hour post exercise to 305.9±78.8 pg/mL (P<0.01). No significant difference in IL-6 and Cortisol concentrations was observed between the two exercise protocols (P=0.13, P=0.10 accordingly). Conclusions. In conclusion, prolonged constant and alternating intensity exercise of the same mean intensity and duration seemed to provoke similar changes in aspects of immune response in healthy subjects.

Eccentric exercise has been extensively used as a model to study muscle damage-induced neuromuscular impairment, adopting mainly a bilateral matching task between the reference (unexercised) arm and the indicator (exercised) arm. However, little attention has been given to the muscle proprioceptive function when the exercised arm acts as its own reference. This study investigated muscle proprioception and motor control, with the arm acting both as reference and indicator, following eccentric exercise and compared them with those observed after isometric exercise. Fourteen young male volunteers were equally divided into two groups and performed an eccentric or isometric exercise protocol with the elbow flexors of the non-dominant arm on an isokinetic dynamometer. Both exercise protocols induced significant changes in indicators of muscle damage, that is, muscle soreness, range of motion and maximal isometric force post-exercise (p < 0.050.001), and neuromuscular function was similarly affected following both protocols. Perception of force was impaired over the 4-day post-exercise period (p < 0.001), with the applied force being systematically overestimated. Perception of joint position was significantly disturbed (i.e., target angle was underestimated) only at one elbow angle on day 4 post-exercise (p < 0.05). The misjudgements and disturbed motor output observed when the exercised arm acted as its own reference concur with the view that they could be a result of a mismatch between the central motor command and an impaired motor control after muscle damage. © 2010 Informa Healthcare Ltd.

Muscular adaptation which occurs following eccentric exercise-induced muscle damage has been associated with changes in the mechanical properties of muscle manifested as a shift in the length-tension relationship towards longer muscle lengths. However, it is not clear whether this shift is a long term adaptation to eccentric exercise. The purpose of this study was to investigate functional adaptations to skeletal muscle damage in humans, tracking such responses several days into muscle recovery. Ten healthy young men performed an eccentric exercise protocol involving the quadriceps muscle and functional measurements were performed before and on days 1, 2, 5, 8, 12 and 16 post-exercise. Blood samples were also withdrawn before and at 6 h, and 2 days, 5 days and 16 days post-exercise. The exercise protocol resulted in muscle damage, indicated by changes in clinical markers including increased serum creatine kinase activity and muscle soreness compared to pre-exercise levels (p<0.05-0.001). An acute, but not sustained shift in the quadriceps isokinetic and isometric angle-torque curves towards longer muscle lengths was observed post-exercise (p<0.05). It was speculated that the functional adaptations following eccentric exercise might be affected by the short resting and functional length of the quadriceps muscle, relative to its optimum. More studies are needed to confirm the hypothesis that a sustained shift in the muscle's length-tension relationship, as an adaptation after lengthening contraction-induced damage, is muscle specific.

Different insulin-like growth factor-1 (IGF-1) isoforms, namely IGF-1Ea, IGF-1Eb and IGF-1Ec (MGF), have been proposed to have various functions in muscle repair and growth. To gain insight into the potentially differential actions of IGF-1 isoforms in the regulation of muscle regeneration, we assessed the time course of their expressions at both mRNA and protein levels after exercise-induced muscle damage in humans. In addition, we characterized mature IGF-1 and synthetic MGF E peptide signalling in C2C12 myoblast-like cells in vitro. Ten healthy male volunteers were subjected to exercise-induced muscle damage and biopsy samples were taken from the exercised muscles before and 6 h, 2, 5 and 16 days post exercise. Muscle damage was documented by specific functional and biochemical responses post exercise. PCR-based analyses of muscle biopsy samples revealed a rapid and transient up-regulation of MGF mRNA expression which was followed by a prolonged increase of IGF-1Ea and IGF-1Eb mRNA expression (p<0.05). Patterns similar to those for mRNA expression were detected for MGF and IGF-1Ea expression at the protein level. The action of synthetic MGF E peptide differed from that of mature IGF-1 since its proliferative effect on C2C12 myoblast-like cells was not blocked by an anti-IGF-1 receptor neutralizing antibody and it did not phosphorylate Akt. Therefore, we conclude that the differential expression profile of IGF-1 isoforms in vivo and the possible IGF-1R - independent MGF E peptide signalling in skeletal muscle-like cells in vitro support the notion that tissue-specific mRNA expression of MGF isoform produces mature IGF-1 and MGF E peptides which possibly act as distinct mitogens in skeletal muscle regeneration.

PURPOSE: There is evidence to suggest that muscle damage caused by resistance exercise (RE) may increase postprandial lipemia (PPL). This study examined PPL for two consecutive days after a protocol of low-volume eccentric RE that caused muscle damage. METHODS: Nine healthy, untrained male volunteers aged 27.2 ± 1.1 yr performed a session of eccentric RE consisting of eight sets of inclined leg presses at six repetition maximum with 3-min rest intervals. A high-fat meal (1.2 g fat, 1.2 g carbohydrate, 0.22 g protein, and 68.6 kJ•kg -1 body mass) was administered 16 h (day 1) and 40 h (day 2) after exercise as well as after an overnight fast with no prior exercise (control condition [C]). Venous blood samples were obtained before and hourly for 6 h after each meal. RESULTS: The duration of the exercise session (including rest intervals) was 25.6 ± 0.2 min, whereas net exercise time was 4.6 ± 0.2 min. Total energy expenditure was 0.64 ± 0.04 MJ. Serum creatine kinase and ratings of perceived muscle soreness were significantly elevated on day 1 and peaked on day 2. Triacylglycerol total area under the curve was 12.1% lower on day 1 compared with C (7.51 ± 0.99 vs. 8.54 ± 1.07 mmol•L -1•6 h -1, P < 0.02), whereas no difference existed between C and day 2. Serum insulin incremental area under the curve was significantly elevated on day 2 compared with C, indicating transient insulin resistance. CONCLUSION: These results show that low-volume eccentric RE is effective in reducing postprandial triacylglycerol concentration despite the low energy expenditure. Muscle damage does not have a detrimental effect on PPL. © 2009 by the American College of Sports Medicine.

Background: Muscle adaptation which occurs following eccentric exercise-induced muscle damage has been associated with an acute inflammatory response. The purpose of this study was to investigate serum interleukin-6 (IL-6), osteoprotegerin and receptor activator of nuclear factor kB ligand (OPG/RANKL) concentrations following muscle damage. We measured changes for several days following muscle damage. Methods: Ten healthy young males performed an eccentric exercise protocol using their quadriceps. Blood samples were withdrawn before and at 6 h, 2 days, 5 days and 16 days post-exercise. Functional and clinical measurements were performed before, and on days 1, 2, 5, 8, 12 and 16 post-exercise. Results: The exercise protocol resulted in muscle damage, indicated by changes in biochemical markers. An increase in IL-6 and OPG, and a decrease in RANKL concentrations were seen at 6 h and on day 2 post-exercise; the OPG:RANKL ratio was increased at 6 h post-exercise (p<0.05). Conclusions: Changes in IL-6 and OPG/RANKL system may represent systemic responses in muscle inflammation and repair processes. However, further studies are needed to elucidate a potential systemic and/or local role of the OPG/RANKL system in skeletal muscle repair. © 2009 by Walter de Gruyter.

Muscular adaptation which occurs following eccentric exercise-induced muscle damage has been associated with changes in the mechanical properties of muscle manifested as a shift in the length-tension relationship towards longer muscle lengths. However, it is not clear whether this shift is a long term adaptation to eccentric exercise. The purpose of this study was to investigate functional adaptations to skeletal muscle damage in humans, tracking such responses several days into muscle recovery. Ten healthy young men performed an eccentric exercise protocol involving the quadriceps muscle and functional measurements were performed before and on days 1, 2, 5, 8, 12 and 16 post-exercise. Blood samples were also withdrawn before and at 6 h, and 2 days, 5 days and 16 days post-exercise. The exercise protocol resulted in muscle damage, indicated by changes in clinical markers including increased serum creatine kinase activity and muscle soreness compared to pre-exercise levels (p<0.05-0.001). An acute, but not sustained shift in the quadriceps isokinetic and isometric angle-torque curves towards longer muscle lengths was observed post-exercise (p<0.05). It was speculated that the functional adaptations following eccentric exercise might be affected by the short resting and functional length of the quadriceps muscle, relative to its optimum. More studies are needed to confirm the hypothesis that a sustained shift in the muscle's length-tension relationship, as an adaptation after lengthening contraction-induced damage, is muscle specific.

Different insulin-like growth factor-1 (IGF-1) isoforms, namely IGF-1Ea, IGF-1Eb and IGF-1Ec (MGF), have been proposed to have various functions in muscle repair and growth. To gain insight into the potentially differential actions of IGF-1 isoforms in the regulation of muscle regeneration, we assessed the time course of their expressions at both mRNA and protein levels after exercise-induced muscle damage in humans. In addition, we characterized mature IGF-1 and synthetic MGF E peptide signalling in C2C12 myoblast-like cells in vitro. Ten healthy male volunteers were subjected to exercise-induced muscle damage and biopsy samples were taken from the exercised muscles before and 6 h, 2, 5 and 16 days post exercise. Muscle damage was documented by specific functional and biochemical responses post exercise. PCR-based analyses of muscle biopsy samples revealed a rapid and transient up-regulation of MGF mRNA expression which was followed by a prolonged increase of IGF-1Ea and IGF-1Eb mRNA expression (p<0.05). Patterns similar to those for mRNA expression were detected for MGF and IGF-1Ea expression at the protein level. The action of synthetic MGF E peptide differed from that of mature IGF-1 since its proliferative effect on C2C12 myoblast-like cells was not blocked by an anti-IGF-1 receptor neutralizing antibody and it did not phosphorylate Akt. Therefore, we conclude that the differential expression profile of IGF-1 isoforms in vivo and the possible IGF-1R - independent MGF E peptide signalling in skeletal muscle-like cells in vitro support the notion that tissue-specific mRNA expression of MGF isoform produces mature IGF-1 and MGF E peptides which possibly act as distinct mitogens in skeletal muscle regeneration.

PURPOSE: There is evidence to suggest that muscle damage caused by resistance exercise (RE) may increase postprandial lipemia (PPL). This study examined PPL for two consecutive days after a protocol of low-volume eccentric RE that caused muscle damage. METHODS: Nine healthy, untrained male volunteers aged 27.2 ± 1.1 yr performed a session of eccentric RE consisting of eight sets of inclined leg presses at six repetition maximum with 3-min rest intervals. A high-fat meal (1.2 g fat, 1.2 g carbohydrate, 0.22 g protein, and 68.6 kJ•kg -1 body mass) was administered 16 h (day 1) and 40 h (day 2) after exercise as well as after an overnight fast with no prior exercise (control condition [C]). Venous blood samples were obtained before and hourly for 6 h after each meal. RESULTS: The duration of the exercise session (including rest intervals) was 25.6 ± 0.2 min, whereas net exercise time was 4.6 ± 0.2 min. Total energy expenditure was 0.64 ± 0.04 MJ. Serum creatine kinase and ratings of perceived muscle soreness were significantly elevated on day 1 and peaked on day 2. Triacylglycerol total area under the curve was 12.1% lower on day 1 compared with C (7.51 ± 0.99 vs. 8.54 ± 1.07 mmol•L -1•6 h -1, P < 0.02), whereas no difference existed between C and day 2. Serum insulin incremental area under the curve was significantly elevated on day 2 compared with C, indicating transient insulin resistance. CONCLUSION: These results show that low-volume eccentric RE is effective in reducing postprandial triacylglycerol concentration despite the low energy expenditure. Muscle damage does not have a detrimental effect on PPL. © 2009 by the American College of Sports Medicine.

Background: Muscle adaptation which occurs following eccentric exercise-induced muscle damage has been associated with an acute inflammatory response. The purpose of this study was to investigate serum interleukin-6 (IL-6), osteoprotegerin and receptor activator of nuclear factor kB ligand (OPG/RANKL) concentrations following muscle damage. We measured changes for several days following muscle damage. Methods: Ten healthy young males performed an eccentric exercise protocol using their quadriceps. Blood samples were withdrawn before and at 6 h, 2 days, 5 days and 16 days post-exercise. Functional and clinical measurements were performed before, and on days 1, 2, 5, 8, 12 and 16 post-exercise. Results: The exercise protocol resulted in muscle damage, indicated by changes in biochemical markers. An increase in IL-6 and OPG, and a decrease in RANKL concentrations were seen at 6 h and on day 2 post-exercise; the OPG:RANKL ratio was increased at 6 h post-exercise (p<0.05). Conclusions: Changes in IL-6 and OPG/RANKL system may represent systemic responses in muscle inflammation and repair processes. However, further studies are needed to elucidate a potential systemic and/or local role of the OPG/RANKL system in skeletal muscle repair. © 2009 by Walter de Gruyter.

Muscular adaptation which occurs following eccentric exercise-induced muscle damage has been associated with changes in the mechanical properties of muscle manifested as a shift in the length-tension relationship towards longer muscle lengths. However, it is not clear whether this shift is a long term adaptation to eccentric exercise. The purpose of this study was to investigate functional adaptations to skeletal muscle damage in humans, tracking such responses several days into muscle recovery. Ten healthy young men performed an eccentric exercise protocol involving the quadriceps muscle and functional measurements were performed before and on days 1, 2, 5, 8, 12 and 16 post-exercise. Blood samples were also withdrawn before and at 6 h, and 2 days, 5 days and 16 days post-exercise. The exercise protocol resulted in muscle damage, indicated by changes in clinical markers including increased serum creatine kinase activity and muscle soreness compared to pre-exercise levels (p<0.05-0.001). An acute, but not sustained shift in the quadriceps isokinetic and isometric angle-torque curves towards longer muscle lengths was observed post-exercise (p<0.05). It was speculated that the functional adaptations following eccentric exercise might be affected by the short resting and functional length of the quadriceps muscle, relative to its optimum. More studies are needed to confirm the hypothesis that a sustained shift in the muscle's length-tension relationship, as an adaptation after lengthening contraction-induced damage, is muscle specific.

Different insulin-like growth factor-1 (IGF-1) isoforms, namely IGF-1Ea, IGF-1Eb and IGF-1Ec (MGF), have been proposed to have various functions in muscle repair and growth. To gain insight into the potentially differential actions of IGF-1 isoforms in the regulation of muscle regeneration, we assessed the time course of their expressions at both mRNA and protein levels after exercise-induced muscle damage in humans. In addition, we characterized mature IGF-1 and synthetic MGF E peptide signalling in C2C12 myoblast-like cells in vitro. Ten healthy male volunteers were subjected to exercise-induced muscle damage and biopsy samples were taken from the exercised muscles before and 6 h, 2, 5 and 16 days post exercise. Muscle damage was documented by specific functional and biochemical responses post exercise. PCR-based analyses of muscle biopsy samples revealed a rapid and transient up-regulation of MGF mRNA expression which was followed by a prolonged increase of IGF-1Ea and IGF-1Eb mRNA expression (p<0.05). Patterns similar to those for mRNA expression were detected for MGF and IGF-1Ea expression at the protein level. The action of synthetic MGF E peptide differed from that of mature IGF-1 since its proliferative effect on C2C12 myoblast-like cells was not blocked by an anti-IGF-1 receptor neutralizing antibody and it did not phosphorylate Akt. Therefore, we conclude that the differential expression profile of IGF-1 isoforms in vivo and the possible IGF-1R - independent MGF E peptide signalling in skeletal muscle-like cells in vitro support the notion that tissue-specific mRNA expression of MGF isoform produces mature IGF-1 and MGF E peptides which possibly act as distinct mitogens in skeletal muscle regeneration.

PURPOSE: There is evidence to suggest that muscle damage caused by resistance exercise (RE) may increase postprandial lipemia (PPL). This study examined PPL for two consecutive days after a protocol of low-volume eccentric RE that caused muscle damage. METHODS: Nine healthy, untrained male volunteers aged 27.2 ± 1.1 yr performed a session of eccentric RE consisting of eight sets of inclined leg presses at six repetition maximum with 3-min rest intervals. A high-fat meal (1.2 g fat, 1.2 g carbohydrate, 0.22 g protein, and 68.6 kJ•kg -1 body mass) was administered 16 h (day 1) and 40 h (day 2) after exercise as well as after an overnight fast with no prior exercise (control condition [C]). Venous blood samples were obtained before and hourly for 6 h after each meal. RESULTS: The duration of the exercise session (including rest intervals) was 25.6 ± 0.2 min, whereas net exercise time was 4.6 ± 0.2 min. Total energy expenditure was 0.64 ± 0.04 MJ. Serum creatine kinase and ratings of perceived muscle soreness were significantly elevated on day 1 and peaked on day 2. Triacylglycerol total area under the curve was 12.1% lower on day 1 compared with C (7.51 ± 0.99 vs. 8.54 ± 1.07 mmol•L -1•6 h -1, P < 0.02), whereas no difference existed between C and day 2. Serum insulin incremental area under the curve was significantly elevated on day 2 compared with C, indicating transient insulin resistance. CONCLUSION: These results show that low-volume eccentric RE is effective in reducing postprandial triacylglycerol concentration despite the low energy expenditure. Muscle damage does not have a detrimental effect on PPL. © 2009 by the American College of Sports Medicine.

Background: Muscle adaptation which occurs following eccentric exercise-induced muscle damage has been associated with an acute inflammatory response. The purpose of this study was to investigate serum interleukin-6 (IL-6), osteoprotegerin and receptor activator of nuclear factor kB ligand (OPG/RANKL) concentrations following muscle damage. We measured changes for several days following muscle damage. Methods: Ten healthy young males performed an eccentric exercise protocol using their quadriceps. Blood samples were withdrawn before and at 6 h, 2 days, 5 days and 16 days post-exercise. Functional and clinical measurements were performed before, and on days 1, 2, 5, 8, 12 and 16 post-exercise. Results: The exercise protocol resulted in muscle damage, indicated by changes in biochemical markers. An increase in IL-6 and OPG, and a decrease in RANKL concentrations were seen at 6 h and on day 2 post-exercise; the OPG:RANKL ratio was increased at 6 h post-exercise (p<0.05). Conclusions: Changes in IL-6 and OPG/RANKL system may represent systemic responses in muscle inflammation and repair processes. However, further studies are needed to elucidate a potential systemic and/or local role of the OPG/RANKL system in skeletal muscle repair. © 2009 by Walter de Gruyter.

This study examined selected anthropometric characteristics of young rowers and compared them with those of senior national level athletes and untrained children, in order to establish a rowing specific anthropometric profile for young athletes. Anthropometric characteristics were measured in 509 club-level rowers aged 11-16 years and 29 male senior national level rowers. Club-level athletes were categorized in 6 age groups (11-16 y), while the senior national level rowers were divided into heavyweight (H-W) and lightweight (L-W). Rowers aged 15 and 16 y had similar height, body weight, arm length and leg length, but lower lean body mass (5 to 8.3 Kg less) compared with senior L-W rowers. Comparison of the young rowers with a reference group of untrained Greek children by means of percentiles (P) revealed that rowers in all age groups were heavier (P63 to P75), taller (P82 to P90) but had a lower body mass index than the mean values (P50) of the reference group after the age of 14 (P48 to P43). Skinfold thicknesses and body fat decreased from the 11 y through to the 16 y group (from 22.9% to 17.8%), and were lower in the two senior groups (9.6% for the L-W and 12.3% for the H-W). Endomorphy ratings decreased with age from 11 to 14 y, but there was no difference between the 14 to 16 y old groups. Mesomorphy was similar across all groups examined and ectomorphy did not show large fluctuations from the 13 y old group onwards. Somatotype of the 15 y old group was 2.4-4.4-3.4 (endo-mesoectomorphy) and was identical to that of the 16 y group and the lightweight senior rowers. The results of this study showed that the club level rowers aged 15 and 16 yrs have similar body structure but different body composition compared with the senior L-W rowers. Anthropometric characteristics can be used as a criterion for selection of rowers by the coaches from an early age.

Seven 6 s sprints with 30 s recovery between sprints were performed against two resistive loads: 50 (L50) and 100 (L100) g · kg-1 body mass. Inertia-corrected and -uncorrected peak and mean power output were calculated. Corrected peak power output in corresponding sprints and the drop in peak power output relative to sprint 1 were not different in the two conditions, despite the fact that mean power output was 15-20% higher in L100 (P < 0.01). The effect of inertia correction on power output was more pronounced for the lighter load (L50), with uncorrected peak power output in sprint 1 being 42% lower than the corresponding corrected peak power output, while this was only 16% in L100. Fatigue assessed by the drop in uncorrected peak and mean power output in sprint 7 relative to sprint 1 was less compared with that obtained by corrected power values, especially in L50 (drop in uncorrected vs. corrected peak power output: 13.3 ± 2.2% vs. 23.1 ± 4.1%, P < 0.01). However, in L100, the difference between the drop in corrected and uncorrected mean power output in sprint 7 was much smaller (24.2 ± 3.1% and 21.2 ± 2.7%, P < 0.01), indicating that fatigue may be safely assessed even without inertia correction when a heavy load is used. In conclusion, when inertia correction is performed, fatigue during repeated sprints is unaffected by resistive load. When inertia correction is omitted, both power output and the fatigue profile are underestimated by an amount dependent on resistive load. In cases where inertia correction is not possible during a repeated sprints test, a heavy load may be preferable.

{The aim of this study was to determine the relative exercise intensity that elicits maximal fat oxidation during walking in inactive and overweight men and women and evaluate any possible sex differences. Forty six healthy, sedentary, overweight men (age: 36.3±1.3 years, body fat: 28.8 ± 0.8%

This study examined selected anthropometric characteristics of young rowers and compared them with those of senior national level athletes and untrained children, in order to establish a rowing specific anthropometric profile for young athletes. Anthropometric characteristics were measured in 509 club-level rowers aged 11-16 years and 29 male senior national level rowers. Club-level athletes were categorized in 6 age groups (11-16 y), while the senior national level rowers were divided into heavyweight (H-W) and lightweight (L-W). Rowers aged 15 and 16 y had similar height, body weight, arm length and leg length, but lower lean body mass (5 to 8.3 Kg less) compared with senior L-W rowers. Comparison of the young rowers with a reference group of untrained Greek children by means of percentiles (P) revealed that rowers in all age groups were heavier (P63 to P75), taller (P82 to P90) but had a lower body mass index than the mean values (P50) of the reference group after the age of 14 (P48 to P43). Skinfold thicknesses and body fat decreased from the 11 y through to the 16 y group (from 22.9% to 17.8%), and were lower in the two senior groups (9.6% for the L-W and 12.3% for the H-W). Endomorphy ratings decreased with age from 11 to 14 y, but there was no difference between the 14 to 16 y old groups. Mesomorphy was similar across all groups examined and ectomorphy did not show large fluctuations from the 13 y old group onwards. Somatotype of the 15 y old group was 2.4-4.4-3.4 (endo-mesoectomorphy) and was identical to that of the 16 y group and the lightweight senior rowers. The results of this study showed that the club level rowers aged 15 and 16 yrs have similar body structure but different body composition compared with the senior L-W rowers. Anthropometric characteristics can be used as a criterion for selection of rowers by the coaches from an early age.

Seven 6 s sprints with 30 s recovery between sprints were performed against two resistive loads: 50 (L50) and 100 (L100) g · kg-1 body mass. Inertia-corrected and -uncorrected peak and mean power output were calculated. Corrected peak power output in corresponding sprints and the drop in peak power output relative to sprint 1 were not different in the two conditions, despite the fact that mean power output was 15-20% higher in L100 (P < 0.01). The effect of inertia correction on power output was more pronounced for the lighter load (L50), with uncorrected peak power output in sprint 1 being 42% lower than the corresponding corrected peak power output, while this was only 16% in L100. Fatigue assessed by the drop in uncorrected peak and mean power output in sprint 7 relative to sprint 1 was less compared with that obtained by corrected power values, especially in L50 (drop in uncorrected vs. corrected peak power output: 13.3 ± 2.2% vs. 23.1 ± 4.1%, P < 0.01). However, in L100, the difference between the drop in corrected and uncorrected mean power output in sprint 7 was much smaller (24.2 ± 3.1% and 21.2 ± 2.7%, P < 0.01), indicating that fatigue may be safely assessed even without inertia correction when a heavy load is used. In conclusion, when inertia correction is performed, fatigue during repeated sprints is unaffected by resistive load. When inertia correction is omitted, both power output and the fatigue profile are underestimated by an amount dependent on resistive load. In cases where inertia correction is not possible during a repeated sprints test, a heavy load may be preferable.

{The aim of this study was to determine the relative exercise intensity that elicits maximal fat oxidation during walking in inactive and overweight men and women and evaluate any possible sex differences. Forty six healthy, sedentary, overweight men (age: 36.3±1.3 years, body fat: 28.8 ± 0.8%

This study examined selected anthropometric characteristics of young rowers and compared them with those of senior national level athletes and untrained children, in order to establish a rowing specific anthropometric profile for young athletes. Anthropometric characteristics were measured in 509 club-level rowers aged 11-16 years and 29 male senior national level rowers. Club-level athletes were categorized in 6 age groups (11-16 y), while the senior national level rowers were divided into heavyweight (H-W) and lightweight (L-W). Rowers aged 15 and 16 y had similar height, body weight, arm length and leg length, but lower lean body mass (5 to 8.3 Kg less) compared with senior L-W rowers. Comparison of the young rowers with a reference group of untrained Greek children by means of percentiles (P) revealed that rowers in all age groups were heavier (P63 to P75), taller (P82 to P90) but had a lower body mass index than the mean values (P50) of the reference group after the age of 14 (P48 to P43). Skinfold thicknesses and body fat decreased from the 11 y through to the 16 y group (from 22.9% to 17.8%), and were lower in the two senior groups (9.6% for the L-W and 12.3% for the H-W). Endomorphy ratings decreased with age from 11 to 14 y, but there was no difference between the 14 to 16 y old groups. Mesomorphy was similar across all groups examined and ectomorphy did not show large fluctuations from the 13 y old group onwards. Somatotype of the 15 y old group was 2.4-4.4-3.4 (endo-mesoectomorphy) and was identical to that of the 16 y group and the lightweight senior rowers. The results of this study showed that the club level rowers aged 15 and 16 yrs have similar body structure but different body composition compared with the senior L-W rowers. Anthropometric characteristics can be used as a criterion for selection of rowers by the coaches from an early age.

Seven 6 s sprints with 30 s recovery between sprints were performed against two resistive loads: 50 (L50) and 100 (L100) g · kg-1 body mass. Inertia-corrected and -uncorrected peak and mean power output were calculated. Corrected peak power output in corresponding sprints and the drop in peak power output relative to sprint 1 were not different in the two conditions, despite the fact that mean power output was 15-20% higher in L100 (P < 0.01). The effect of inertia correction on power output was more pronounced for the lighter load (L50), with uncorrected peak power output in sprint 1 being 42% lower than the corresponding corrected peak power output, while this was only 16% in L100. Fatigue assessed by the drop in uncorrected peak and mean power output in sprint 7 relative to sprint 1 was less compared with that obtained by corrected power values, especially in L50 (drop in uncorrected vs. corrected peak power output: 13.3 ± 2.2% vs. 23.1 ± 4.1%, P < 0.01). However, in L100, the difference between the drop in corrected and uncorrected mean power output in sprint 7 was much smaller (24.2 ± 3.1% and 21.2 ± 2.7%, P < 0.01), indicating that fatigue may be safely assessed even without inertia correction when a heavy load is used. In conclusion, when inertia correction is performed, fatigue during repeated sprints is unaffected by resistive load. When inertia correction is omitted, both power output and the fatigue profile are underestimated by an amount dependent on resistive load. In cases where inertia correction is not possible during a repeated sprints test, a heavy load may be preferable.

The aim of this study was to determine the relative exercise intensity that elicits maximal fat oxidation during walking in inactive and overweight men and women and evaluate any possible sex differences. Forty six healthy, sedentary, overweight men (age: 36.3±1.3 years, body fat: 28.8 ± 0.8%, n = 28, mean ± SE) and women (age: 36.6±1.8 years, body fat: 37.1 ± 0.8%, n = 18) participated in the study. Fat oxidation was calculated from expired air analysis using indirect calorimetry during an incremental treadmill walking test. Peak fat oxidation rate (PFO) was higher in men compared to women (0.31 ± 0.02 vs. 0.20 ± 0.02 g.min-1; p < 0.001), but this difference disappeared when PFO was scaled per kg fat-free mass (4.36 ± 0.23 vs. 3.99 ± 0.37 mg.kg fat free mass -1.min-1). Also, the relative exercise intensity at which PFO occurred was similar for men and women and corresponded to 40.1 ± 1.8 and 39.5 ± 2.3% of maximal oxygen uptake (VO2max) and 60.0 ± 1.4 and 57.8 ± 1.4% of maximal heart rate, respectively. The walking speed corresponding to PFO was 5.5 ± 0.2 and 5.0 ± 0.1 km·h-1 for men and women, respectively. Regression analysis showed that sex, FFM and VO2max were significant predictors of PFO expressed in g.min-1 (adjusted R2 = 0.48, p = 0.01). However when PFO was scaled per kg FFM, only a small part of the variance was explained by VO2max (adjusted R2 = 0.12, p < 0.05). In conclusion, peak fat oxidation rate and the corresponding relative exercise intensity were similar in male and female overweight and sedentary individuals, but lower compared to those reported for leaner and/or physically active persons. Walking at a moderate speed (5.0-5.5 km·h-1) may be used as a convenient way to exercise at an intensity eliciting peak fat oxidation in overweight individuals. ©Journal of Sports Science and Medicine (2008).

{This study evaluated and compared the effectiveness of two different off-season, short-term basketball training programs on physical and technical abilities of young basketball players. Twenty-seven adolescent basketball players (14.7 ± 0.5 years; Tanner stage: 3.5 ± 0.5) were randomly divided into a specialized basketball training group (SP

Aim. This study examined the ventilatory responses and blood lactate concentration after a simulated synchronized swimming routine of athletes of two different age categories. Methods. Sixteen trained female synchronized swimmers, 8 competing at the comen category (age: 13.8±0.2 years) and 8 competing at the senior category (age: 22.6±0.9 years), performed a maximal 400 m swimming test and a simulated synchronized swimming routine. Oxygen uptake (V̇O2) of the tests was obtained by backward extrapolation of a monoexponential curve fitted to the postexercise oxygen uptake data. Results. There were no differences in V̇O2 at the end of the routine (37.4±2.7 vs 40.5±2 mL·kg -1·min-1, or 81.8±3.1% and 85.8±2.7% of V̇O2peak) and blood lactate (5.7*0.9 vs 4.5±0.4 mmol-L-1) between senior and comen synchronized swimmers. There was no difference in the half-time of V̇O2 decay (T1/2) between the athletes of the two categories, but T1/2 was significantly higher after the routine compared with the V̇O2peak test for both categories (senior: 45.2±5.9 vs 33.1±2.1 s, P<0.05, comen: 38.2±6 vs 27.4±8.2 s, P<0.05). The mean end-tidal pressure of CO2 during the second half of the recovery was higher after the routine than after the V̇O2peak test (37.2±1.4 vs 34.5±1.5 mmHg, P<0.05), possibly due to the prolonged periods of breath holding (55±4% of routine time). Breathing frequency was also high (30±2.2 breaths.min-1) at the later part of recovery after the routine. Conclusion. Cardiorespiratory and metabolic responses to a simulated synchronized swimming routine were similar in senior and comen athletes. The slower recovery of V̇O2 after the routine could be related to the elevated cost of ventilation, especially during the later stages of recovery, possibly as a result of the prolonged apnea.

This study examined the effects of two resistive loads on fatigue during repeated sprints in children. Twelve 11.8 (0.2) year old boys performed a force-velocity test to determine the load (Fopt) corresponding to the optimal pedal rate. On two separate occasions, ten 6-s sprints interspersed with 24-s recovery intervals were performed on a friction-loaded cycle ergometer, against a load equal to Fopt or 50%Fopt. Although mean power output (MPO) was higher in the Fopt [397 (24) and 356 (19) W, P < 0.01], the decline in MPO over the 10 sprints was similar in Fopt [8.8 (1.9) %] and 50%Fopt [9.0 (2.4) %]. In contrast, peak power (PPO) was not different in sprint 1 between the two conditions [459 (24) and 460 (28) W], but was decreased only in 50%Fopt [11.4 (3.2) %, P < 0.01], while it was maintained in the Fopt despite the higher total work during each sprint. Fatigue within each sprint (percent drop from peak to end power output) was also higher in the 50%Fopt compared with the Fopt [32 (2.5) vs. 10 (1.6) %, P < 0.01]. Peak and mean pedal rate in Fopt condition were close to the optimum (Vopt), while a large part of the sprint time in 50%Fopt was spent far from Vopt. The present study shows that sprinting against Fopt reduces fatigue within and between repeated short sprints in children. It is suggested that fatigue during repeated sprints is modified when pedal rate is not close to Vopt, according to the parabolic power versus pedal rate relationship. © Springer-Verlag 2007.

This study investigated the hypothesis that isotonic muscle performance following mild muscle damage would be disproportionately affected when measured at different parts of the range of motion. Seven male volunteers performed 50 maximal isometric contractions with the elbow flexors at a lengthened position. Maximal isotonic performance was measured before and for four days post-exercise at two parts of the range of motion of elbow flexion, including mainly the descending (L) or the ascending limb (S) of the angle-force curve. On day 1 post-exercise, muscle damage was evidenced by a decrease in peak isometric force (-20.3 ± 2.7%, p<0.01), a shift in optimum angle for force generation towards a greater elbow angle (by 0.12 ± 0.03 rad, p<0.05), and an increase in serum creatine kinase activity and muscle soreness (P<0.01). Isotonic performance indices were decreased only in the S condition (p<0.01). Shift in optimum angle and isotonic performance indices recovered on day 2. The disproportionate decrease in isotonic performance in the S condition may be explained by the shift of the optimum angle towards a longer muscle length, which would benefit force generation at elbow angles beyond the optimum angle but impair force at the more acute elbow angles. © 2007 - IOS Press and the authors. All rights reserved.

Aim. This study examined the ventilatory responses and blood lactate concentration after a simulated synchronized swimming routine of athletes of two different age categories. Methods. Sixteen trained female synchronized swimmers, 8 competing at the comen category (age: 13.8±0.2 years) and 8 competing at the senior category (age: 22.6±0.9 years), performed a maximal 400 m swimming test and a simulated synchronized swimming routine. Oxygen uptake (V̇O2) of the tests was obtained by backward extrapolation of a monoexponential curve fitted to the postexercise oxygen uptake data. Results. There were no differences in V̇O2 at the end of the routine (37.4±2.7 vs 40.5±2 mL·kg -1·min-1, or 81.8±3.1% and 85.8±2.7% of V̇O2peak) and blood lactate (5.7*0.9 vs 4.5±0.4 mmol-L-1) between senior and comen synchronized swimmers. There was no difference in the half-time of V̇O2 decay (T1/2) between the athletes of the two categories, but T1/2 was significantly higher after the routine compared with the V̇O2peak test for both categories (senior: 45.2±5.9 vs 33.1±2.1 s, P<0.05, comen: 38.2±6 vs 27.4±8.2 s, P<0.05). The mean end-tidal pressure of CO2 during the second half of the recovery was higher after the routine than after the V̇O2peak test (37.2±1.4 vs 34.5±1.5 mmHg, P<0.05), possibly due to the prolonged periods of breath holding (55±4% of routine time). Breathing frequency was also high (30±2.2 breaths.min-1) at the later part of recovery after the routine. Conclusion. Cardiorespiratory and metabolic responses to a simulated synchronized swimming routine were similar in senior and comen athletes. The slower recovery of V̇O2 after the routine could be related to the elevated cost of ventilation, especially during the later stages of recovery, possibly as a result of the prolonged apnea.

{This study evaluated and compared the effectiveness of two different off-season, short-term basketball training programs on physical and technical abilities of young basketball players. Twenty-seven adolescent basketball players (14.7 ± 0.5 years; Tanner stage: 3.5 ± 0.5) were randomly divided into a specialized basketball training group (SP

This study examined the effects of two resistive loads on fatigue during repeated sprints in children. Twelve 11.8 (0.2) year old boys performed a force-velocity test to determine the load (Fopt) corresponding to the optimal pedal rate. On two separate occasions, ten 6-s sprints interspersed with 24-s recovery intervals were performed on a friction-loaded cycle ergometer, against a load equal to Fopt or 50%Fopt. Although mean power output (MPO) was higher in the Fopt [397 (24) and 356 (19) W, P < 0.01], the decline in MPO over the 10 sprints was similar in Fopt [8.8 (1.9) %] and 50%Fopt [9.0 (2.4) %]. In contrast, peak power (PPO) was not different in sprint 1 between the two conditions [459 (24) and 460 (28) W], but was decreased only in 50%Fopt [11.4 (3.2) %, P < 0.01], while it was maintained in the Fopt despite the higher total work during each sprint. Fatigue within each sprint (percent drop from peak to end power output) was also higher in the 50%Fopt compared with the Fopt [32 (2.5) vs. 10 (1.6) %, P < 0.01]. Peak and mean pedal rate in Fopt condition were close to the optimum (Vopt), while a large part of the sprint time in 50%Fopt was spent far from Vopt. The present study shows that sprinting against Fopt reduces fatigue within and between repeated short sprints in children. It is suggested that fatigue during repeated sprints is modified when pedal rate is not close to Vopt, according to the parabolic power versus pedal rate relationship. © Springer-Verlag 2007.

This study investigated the hypothesis that isotonic muscle performance following mild muscle damage would be disproportionately affected when measured at different parts of the range of motion. Seven male volunteers performed 50 maximal isometric contractions with the elbow flexors at a lengthened position. Maximal isotonic performance was measured before and for four days post-exercise at two parts of the range of motion of elbow flexion, including mainly the descending (L) or the ascending limb (S) of the angle-force curve. On day 1 post-exercise, muscle damage was evidenced by a decrease in peak isometric force (-20.3 ± 2.7%, p<0.01), a shift in optimum angle for force generation towards a greater elbow angle (by 0.12 ± 0.03 rad, p<0.05), and an increase in serum creatine kinase activity and muscle soreness (P<0.01). Isotonic performance indices were decreased only in the S condition (p<0.01). Shift in optimum angle and isotonic performance indices recovered on day 2. The disproportionate decrease in isotonic performance in the S condition may be explained by the shift of the optimum angle towards a longer muscle length, which would benefit force generation at elbow angles beyond the optimum angle but impair force at the more acute elbow angles. © 2007 - IOS Press and the authors. All rights reserved.

Aim. This study examined the ventilatory responses and blood lactate concentration after a simulated synchronized swimming routine of athletes of two different age categories. Methods. Sixteen trained female synchronized swimmers, 8 competing at the comen category (age: 13.8±0.2 years) and 8 competing at the senior category (age: 22.6±0.9 years), performed a maximal 400 m swimming test and a simulated synchronized swimming routine. Oxygen uptake (V̇O2) of the tests was obtained by backward extrapolation of a monoexponential curve fitted to the postexercise oxygen uptake data. Results. There were no differences in V̇O2 at the end of the routine (37.4±2.7 vs 40.5±2 mL·kg -1·min-1, or 81.8±3.1% and 85.8±2.7% of V̇O2peak) and blood lactate (5.7*0.9 vs 4.5±0.4 mmol-L-1) between senior and comen synchronized swimmers. There was no difference in the half-time of V̇O2 decay (T1/2) between the athletes of the two categories, but T1/2 was significantly higher after the routine compared with the V̇O2peak test for both categories (senior: 45.2±5.9 vs 33.1±2.1 s, P<0.05, comen: 38.2±6 vs 27.4±8.2 s, P<0.05). The mean end-tidal pressure of CO2 during the second half of the recovery was higher after the routine than after the V̇O2peak test (37.2±1.4 vs 34.5±1.5 mmHg, P<0.05), possibly due to the prolonged periods of breath holding (55±4% of routine time). Breathing frequency was also high (30±2.2 breaths.min-1) at the later part of recovery after the routine. Conclusion. Cardiorespiratory and metabolic responses to a simulated synchronized swimming routine were similar in senior and comen athletes. The slower recovery of V̇O2 after the routine could be related to the elevated cost of ventilation, especially during the later stages of recovery, possibly as a result of the prolonged apnea.

This study evaluated and compared the effectiveness of two different off-season, short-term basketball training programs on physical and technical abilities of young basketball players. Twenty-seven adolescent basketball players (14.7 ± 0.5 years; Tanner stage: 3.5 ± 0.5) were randomly divided into a specialized basketball training group (SP, n = 10), a mixed basketball plus conditioning training group (MX, n = 10) and a control group (n = 7). Training included five sessions per week (100-120 min each) and was performed for 4 weeks. Maximal oxygen uptake was similarly improved after SP (4.9 ± 1.8%) and MX (4.9 ± 1.4%), but there was no effect on ventilatory threshold. Peak and mean power output measured during the Wingate test were also improved by a similar magnitude after SP (21 ± 5%) and MX (15 ± 6%). Trunk muscle endurance was equally increased (SP: 23 ± 4%, MX: 25 ± 5%), but arms endurance was improved significantly more after MX (50 ± 11%) compared to SP (11 ± 14%, p < 0.05). Performance in four basketball technical skills was similarly increased (by 17-27%) in both groups, with a tendency for greater improvement of the SP groups in the technical skills of shooting and passing. These results indicate that a SP basketball training program, performed exclusively on-court was as effective as a MX training program in terms of aerobic and anaerobic fitness improvement. Furthermore, the decrease of the total on-court training time in the MX group resulted in a tendency for a smaller improvement of basketball technical skills. In conclusion, both SP and MX training are equally effective in order to limit and/or reverse the detraining effects that occur during the off-season in basketball. © 2006 Sports Medicine Australia.

This study examined the effects of two resistive loads on fatigue during repeated sprints in children. Twelve 11.8 (0.2) year old boys performed a force-velocity test to determine the load (Fopt) corresponding to the optimal pedal rate. On two separate occasions, ten 6-s sprints interspersed with 24-s recovery intervals were performed on a friction-loaded cycle ergometer, against a load equal to Fopt or 50%Fopt. Although mean power output (MPO) was higher in the Fopt [397 (24) and 356 (19) W, P < 0.01], the decline in MPO over the 10 sprints was similar in Fopt [8.8 (1.9) %] and 50%Fopt [9.0 (2.4) %]. In contrast, peak power (PPO) was not different in sprint 1 between the two conditions [459 (24) and 460 (28) W], but was decreased only in 50%Fopt [11.4 (3.2) %, P < 0.01], while it was maintained in the Fopt despite the higher total work during each sprint. Fatigue within each sprint (percent drop from peak to end power output) was also higher in the 50%Fopt compared with the Fopt [32 (2.5) vs. 10 (1.6) %, P < 0.01]. Peak and mean pedal rate in Fopt condition were close to the optimum (Vopt), while a large part of the sprint time in 50%Fopt was spent far from Vopt. The present study shows that sprinting against Fopt reduces fatigue within and between repeated short sprints in children. It is suggested that fatigue during repeated sprints is modified when pedal rate is not close to Vopt, according to the parabolic power versus pedal rate relationship. © Springer-Verlag 2007.

This study investigated the hypothesis that isotonic muscle performance following mild muscle damage would be disproportionately affected when measured at different parts of the range of motion. Seven male volunteers performed 50 maximal isometric contractions with the elbow flexors at a lengthened position. Maximal isotonic performance was measured before and for four days post-exercise at two parts of the range of motion of elbow flexion, including mainly the descending (L) or the ascending limb (S) of the angle-force curve. On day 1 post-exercise, muscle damage was evidenced by a decrease in peak isometric force (-20.3 ± 2.7%, p<0.01), a shift in optimum angle for force generation towards a greater elbow angle (by 0.12 ± 0.03 rad, p<0.05), and an increase in serum creatine kinase activity and muscle soreness (P<0.01). Isotonic performance indices were decreased only in the S condition (p<0.01). Shift in optimum angle and isotonic performance indices recovered on day 2. The disproportionate decrease in isotonic performance in the S condition may be explained by the shift of the optimum angle towards a longer muscle length, which would benefit force generation at elbow angles beyond the optimum angle but impair force at the more acute elbow angles. © 2007 - IOS Press and the authors. All rights reserved.

The aim of this study was to establish an anthropometric profile of young fencers separated into four different age groups and to examine the degree of upper and lower limb asymmetry. Selected anthropometric characteristics were measured in 152 fencers (84 males and 68 females) during the Greek fencing championships. Fencers were divided into 4 age categories (boys/girls, cadets, junior and senior) according to the International Fencing Federation rules. The larger differences in anthropometric characteristics of both males and females were observed between the very young group (10-13yrs) and the older groups, while for most parameters, there were no differences between the two older groups (18-20yrs and >20yrs). There was no significant difference between the 10-13yrs groups of males and females in almost all anthropometric characteristics. Somatotype ratings were relatively stable across age groups. The mean somatotype of male fencers was 3.1-2.6-3.2. The female fencers were mainly situated in the ectomorph -endomorph region, and had a mean somatotype of 3.8-1.8-3.3. Arm CSA was higher in males compared to females in all age groups, except for the 10-13yrs group. However, leg CSA was not different between genders in all age groups. Significant CSA asymmetries were observed between the dominant and the non-dominant sides in the arm and leg in both genders. Arm asymmetries were evident from an early age, while leg asymmetries were not observed in the younger group. The lack of significant differences between males and females for the 10-13yrs groups in most of the anthropometric characteristics, should be taken into account in talent selection. ©2006 Teviot Scientific Publications.

Active recovery reduces blood lactate concentration faster than passive recovery and, when the proper intensity is applied, a positive effect on performance is expected. The purpose of the study was to investigate the effect of different intensities of active recovery on performance during repeated sprint swimming. Nine male well-trained swimmers performed 8 repetitions of 25 m sprints (8 ± 25 m) interspersed with 45 s intervals, followed by a 50 m sprint test 6 min later. During the 45 s and 6 min interval periods, swimmers either rested passively (PAS) or swam at an intensity corresponding to 50% (ACT60) and 60% (ACT60) of their individual 100 m velocity. Blood lactate was higher during PAS compared with ACT50 and ACT60 trials (p < 0.05), whereas plasma ammonia and glycerol concentration were not different between trials (p > 0.05). Mean performance time for the 8 × 25 m sprints was better in the PAS compared with the ACT50 and ACT60 trials (PAS: 13.10 ± 0.07 vs. ACT50: 13.43 ± 0.10 and ACT60: 13.47 ± 0.10s, p < 0.05). The first 25 m sprint was not different across trials (p > 0.05), but performance decreased after sprint 2 during active recovery trials (ACT50 and ACT60) compared with the passive recovery (PAS) trial (p < 0.05). Performance time for the 50 m sprint performed 6 min after the 8 ± 25 m sprints was no different between trials (p > 0.05). These results indicate that active recovery at intensities corresponding to 50% and 60% of the 100 m velocity during repeated swimming sprints decreases performance. Active recovery reduces blood lactate concentration, but does not affect performance on a 50 m sprint when 6 min recovery is provided. Passive recovery is advised during short-interval repeated sprint training in well-trained swimmers. © 2006 NRC Canada.

This study examined the effects of a typical fencing training program on selected hormones, neuromuscular performance, and anthropometric parameters in peripubertal boys. Two sets of measurements, before training and after 12 months of training, were performed on 2 groups of 11- to 13-year-old boys. One group consisted of fencers (n = 8), who trained regularly for the 12-month period, and the other group (n = 8) consisted of inactive children of the same age. There was no difference in Tanner's maturation stage of the 2 groups before (controls, 2.5 ± 0.3; fencers, 2.1 ± 0.3) and after the 12 months (controls, 3.0 ± 0.3; fencers, 3.0 ± 0.3). Serum testosterone, growth hormone, sex hormone binding globulin, free androgen index, and leptin changed significantly over time, reaching similar values in the 2 groups at the end of the study. Significantly greater increases in body mass (16 ± 3%) and leg cross-sectional area (CSA) (32 ± 7%) were observed only in the fencers' group, and these differences disappeared when height was set as a changing covariate. Although there was a greater increase in height for the fencers compared to the control group (8.6 ± 1.2 vs. 3.6 ± 0.9 cm, p < 0.01), the height reached at the end of the study was almost identical in the 2 groups (controls, 163.6 ± 5.1; fencers, 165.4 ± 2.8). Arm CSA, handgrip strength, and vertical jump performance changed significantly over time for both groups, with no differences between groups. It was concluded that a typical fencing training program for peripubertal boys did not have any effect on selected growth and anabolic hormones and did not influence the normal growth process, as this was reflected by changes in selected anthropometric and neuromuscular performance parameters. This may be because of the characteristics of the present fencing training program, which may not be adequate to alter children's hormonal functions in such a way as to override the rapid changes occurring during puberty. © 2006 National Strength & Conditioning Association.

This study examined the effect of recovery time on the maintenance of power output and the heart rate response during repeated maximal rowing exercise. Nine male, junior rowers (age: 16 ± 1 years; body mass: 74.0 ± 9.1 kg; height: 1.78 ± 0.03 m) performed two consecutive all-out 1000 m bouts on a rowing ergometer on three separate occasions. The rest interval between the two bouts was 1.5 (INT1.5), 3 (INT3) and 6 min (INT6), allocated in random order. Power output was averaged for each 1000 m bout and for the first and last 500 m of each bout. Heart rate kinetics were determined using a two-component exponential model. Performance time and mean power output for the first bout was 209 ± 3 s and 313 ± 10 W respectively. Recovery of mean power output was incomplete even after 6 min (78 ± 2, 81 ± 2 and 84 ± 2% for INT1.5, INT3 and INT6 respectively). Mean power output after INT6 was higher (p < 0.01) only compared with INT1.5. Power output during the first 500 m of bout 2 after INT6 was 10% higher compared with the second 500 m. During INT1.5 and INT3 power output during the first and the second 500 m of bout 2 was similar. Peak heart rate (∼197 b·min-1) and the HR time constant (∼13 s) were unaffected by prior exercise and recovery time. However, when the recovery was short (INT1.5), HR during the first 50 s of bout 2 was significantly higher compared with corresponding values during bout 1. The present study has shown that in order to maintain similar power outputs during repeated maximal rowing exercise, the recovery interval must be greater than 6 min. The influence of a longer recovery time (INT6) on maintenance of power output was only evident during the first half of the second 1000 m bout. ©Journal of Sports Science and Medicine.

The aim of this study was to establish an anthropometric profile of young fencers separated into four different age groups and to examine the degree of upper and lower limb asymmetry. Selected anthropometric characteristics were measured in 152 fencers (84 males and 68 females) during the Greek fencing championships. Fencers were divided into 4 age categories (boys/girls, cadets, junior and senior) according to the International Fencing Federation rules. The larger differences in anthropometric characteristics of both males and females were observed between the very young group (10-13yrs) and the older groups, while for most parameters, there were no differences between the two older groups (18-20yrs and >20yrs). There was no significant difference between the 10-13yrs groups of males and females in almost all anthropometric characteristics. Somatotype ratings were relatively stable across age groups. The mean somatotype of male fencers was 3.1-2.6-3.2. The female fencers were mainly situated in the ectomorph -endomorph region, and had a mean somatotype of 3.8-1.8-3.3. Arm CSA was higher in males compared to females in all age groups, except for the 10-13yrs group. However, leg CSA was not different between genders in all age groups. Significant CSA asymmetries were observed between the dominant and the non-dominant sides in the arm and leg in both genders. Arm asymmetries were evident from an early age, while leg asymmetries were not observed in the younger group. The lack of significant differences between males and females for the 10-13yrs groups in most of the anthropometric characteristics, should be taken into account in talent selection. ©2006 Teviot Scientific Publications.

Active recovery reduces blood lactate concentration faster than passive recovery and, when the proper intensity is applied, a positive effect on performance is expected. The purpose of the study was to investigate the effect of different intensities of active recovery on performance during repeated sprint swimming. Nine male well-trained swimmers performed 8 repetitions of 25 m sprints (8 ± 25 m) interspersed with 45 s intervals, followed by a 50 m sprint test 6 min later. During the 45 s and 6 min interval periods, swimmers either rested passively (PAS) or swam at an intensity corresponding to 50% (ACT60) and 60% (ACT60) of their individual 100 m velocity. Blood lactate was higher during PAS compared with ACT50 and ACT60 trials (p < 0.05), whereas plasma ammonia and glycerol concentration were not different between trials (p > 0.05). Mean performance time for the 8 × 25 m sprints was better in the PAS compared with the ACT50 and ACT60 trials (PAS: 13.10 ± 0.07 vs. ACT50: 13.43 ± 0.10 and ACT60: 13.47 ± 0.10s, p < 0.05). The first 25 m sprint was not different across trials (p > 0.05), but performance decreased after sprint 2 during active recovery trials (ACT50 and ACT60) compared with the passive recovery (PAS) trial (p < 0.05). Performance time for the 50 m sprint performed 6 min after the 8 ± 25 m sprints was no different between trials (p > 0.05). These results indicate that active recovery at intensities corresponding to 50% and 60% of the 100 m velocity during repeated swimming sprints decreases performance. Active recovery reduces blood lactate concentration, but does not affect performance on a 50 m sprint when 6 min recovery is provided. Passive recovery is advised during short-interval repeated sprint training in well-trained swimmers. © 2006 NRC Canada.

This study examined the effects of a typical fencing training program on selected hormones, neuromuscular performance, and anthropometric parameters in peripubertal boys. Two sets of measurements, before training and after 12 months of training, were performed on 2 groups of 11- to 13-year-old boys. One group consisted of fencers (n = 8), who trained regularly for the 12-month period, and the other group (n = 8) consisted of inactive children of the same age. There was no difference in Tanner's maturation stage of the 2 groups before (controls, 2.5 ± 0.3; fencers, 2.1 ± 0.3) and after the 12 months (controls, 3.0 ± 0.3; fencers, 3.0 ± 0.3). Serum testosterone, growth hormone, sex hormone binding globulin, free androgen index, and leptin changed significantly over time, reaching similar values in the 2 groups at the end of the study. Significantly greater increases in body mass (16 ± 3%) and leg cross-sectional area (CSA) (32 ± 7%) were observed only in the fencers' group, and these differences disappeared when height was set as a changing covariate. Although there was a greater increase in height for the fencers compared to the control group (8.6 ± 1.2 vs. 3.6 ± 0.9 cm, p < 0.01), the height reached at the end of the study was almost identical in the 2 groups (controls, 163.6 ± 5.1; fencers, 165.4 ± 2.8). Arm CSA, handgrip strength, and vertical jump performance changed significantly over time for both groups, with no differences between groups. It was concluded that a typical fencing training program for peripubertal boys did not have any effect on selected growth and anabolic hormones and did not influence the normal growth process, as this was reflected by changes in selected anthropometric and neuromuscular performance parameters. This may be because of the characteristics of the present fencing training program, which may not be adequate to alter children's hormonal functions in such a way as to override the rapid changes occurring during puberty. © 2006 National Strength & Conditioning Association.

This study examined the effect of recovery time on the maintenance of power output and the heart rate response during repeated maximal rowing exercise. Nine male, junior rowers (age: 16 ± 1 years; body mass: 74.0 ± 9.1 kg; height: 1.78 ± 0.03 m) performed two consecutive all-out 1000 m bouts on a rowing ergometer on three separate occasions. The rest interval between the two bouts was 1.5 (INT1.5), 3 (INT3) and 6 min (INT6), allocated in random order. Power output was averaged for each 1000 m bout and for the first and last 500 m of each bout. Heart rate kinetics were determined using a two-component exponential model. Performance time and mean power output for the first bout was 209 ± 3 s and 313 ± 10 W respectively. Recovery of mean power output was incomplete even after 6 min (78 ± 2, 81 ± 2 and 84 ± 2% for INT1.5, INT3 and INT6 respectively). Mean power output after INT6 was higher (p < 0.01) only compared with INT1.5. Power output during the first 500 m of bout 2 after INT6 was 10% higher compared with the second 500 m. During INT1.5 and INT3 power output during the first and the second 500 m of bout 2 was similar. Peak heart rate (∼197 b·min-1) and the HR time constant (∼13 s) were unaffected by prior exercise and recovery time. However, when the recovery was short (INT1.5), HR during the first 50 s of bout 2 was significantly higher compared with corresponding values during bout 1. The present study has shown that in order to maintain similar power outputs during repeated maximal rowing exercise, the recovery interval must be greater than 6 min. The influence of a longer recovery time (INT6) on maintenance of power output was only evident during the first half of the second 1000 m bout. ©Journal of Sports Science and Medicine.

The aim of this study was to establish an anthropometric profile of young fencers separated into four different age groups and to examine the degree of upper and lower limb asymmetry. Selected anthropometric characteristics were measured in 152 fencers (84 males and 68 females) during the Greek fencing championships. Fencers were divided into 4 age categories (boys/girls, cadets, junior and senior) according to the International Fencing Federation rules. The larger differences in anthropometric characteristics of both males and females were observed between the very young group (10-13yrs) and the older groups, while for most parameters, there were no differences between the two older groups (18-20yrs and >20yrs). There was no significant difference between the 10-13yrs groups of males and females in almost all anthropometric characteristics. Somatotype ratings were relatively stable across age groups. The mean somatotype of male fencers was 3.1-2.6-3.2. The female fencers were mainly situated in the ectomorph -endomorph region, and had a mean somatotype of 3.8-1.8-3.3. Arm CSA was higher in males compared to females in all age groups, except for the 10-13yrs group. However, leg CSA was not different between genders in all age groups. Significant CSA asymmetries were observed between the dominant and the non-dominant sides in the arm and leg in both genders. Arm asymmetries were evident from an early age, while leg asymmetries were not observed in the younger group. The lack of significant differences between males and females for the 10-13yrs groups in most of the anthropometric characteristics, should be taken into account in talent selection. ©2006 Teviot Scientific Publications.

Active recovery reduces blood lactate concentration faster than passive recovery and, when the proper intensity is applied, a positive effect on performance is expected. The purpose of the study was to investigate the effect of different intensities of active recovery on performance during repeated sprint swimming. Nine male well-trained swimmers performed 8 repetitions of 25 m sprints (8 ± 25 m) interspersed with 45 s intervals, followed by a 50 m sprint test 6 min later. During the 45 s and 6 min interval periods, swimmers either rested passively (PAS) or swam at an intensity corresponding to 50% (ACT60) and 60% (ACT60) of their individual 100 m velocity. Blood lactate was higher during PAS compared with ACT50 and ACT60 trials (p < 0.05), whereas plasma ammonia and glycerol concentration were not different between trials (p > 0.05). Mean performance time for the 8 × 25 m sprints was better in the PAS compared with the ACT50 and ACT60 trials (PAS: 13.10 ± 0.07 vs. ACT50: 13.43 ± 0.10 and ACT60: 13.47 ± 0.10s, p < 0.05). The first 25 m sprint was not different across trials (p > 0.05), but performance decreased after sprint 2 during active recovery trials (ACT50 and ACT60) compared with the passive recovery (PAS) trial (p < 0.05). Performance time for the 50 m sprint performed 6 min after the 8 ± 25 m sprints was no different between trials (p > 0.05). These results indicate that active recovery at intensities corresponding to 50% and 60% of the 100 m velocity during repeated swimming sprints decreases performance. Active recovery reduces blood lactate concentration, but does not affect performance on a 50 m sprint when 6 min recovery is provided. Passive recovery is advised during short-interval repeated sprint training in well-trained swimmers. © 2006 NRC Canada.

This study examined the effects of a typical fencing training program on selected hormones, neuromuscular performance, and anthropometric parameters in peripubertal boys. Two sets of measurements, before training and after 12 months of training, were performed on 2 groups of 11- to 13-year-old boys. One group consisted of fencers (n = 8), who trained regularly for the 12-month period, and the other group (n = 8) consisted of inactive children of the same age. There was no difference in Tanner's maturation stage of the 2 groups before (controls, 2.5 ± 0.3; fencers, 2.1 ± 0.3) and after the 12 months (controls, 3.0 ± 0.3; fencers, 3.0 ± 0.3). Serum testosterone, growth hormone, sex hormone binding globulin, free androgen index, and leptin changed significantly over time, reaching similar values in the 2 groups at the end of the study. Significantly greater increases in body mass (16 ± 3%) and leg cross-sectional area (CSA) (32 ± 7%) were observed only in the fencers' group, and these differences disappeared when height was set as a changing covariate. Although there was a greater increase in height for the fencers compared to the control group (8.6 ± 1.2 vs. 3.6 ± 0.9 cm, p < 0.01), the height reached at the end of the study was almost identical in the 2 groups (controls, 163.6 ± 5.1; fencers, 165.4 ± 2.8). Arm CSA, handgrip strength, and vertical jump performance changed significantly over time for both groups, with no differences between groups. It was concluded that a typical fencing training program for peripubertal boys did not have any effect on selected growth and anabolic hormones and did not influence the normal growth process, as this was reflected by changes in selected anthropometric and neuromuscular performance parameters. This may be because of the characteristics of the present fencing training program, which may not be adequate to alter children's hormonal functions in such a way as to override the rapid changes occurring during puberty. © 2006 National Strength & Conditioning Association.

This study examined the effect of recovery time on the maintenance of power output and the heart rate response during repeated maximal rowing exercise. Nine male, junior rowers (age: 16 ± 1 years; body mass: 74.0 ± 9.1 kg; height: 1.78 ± 0.03 m) performed two consecutive all-out 1000 m bouts on a rowing ergometer on three separate occasions. The rest interval between the two bouts was 1.5 (INT1.5), 3 (INT3) and 6 min (INT6), allocated in random order. Power output was averaged for each 1000 m bout and for the first and last 500 m of each bout. Heart rate kinetics were determined using a two-component exponential model. Performance time and mean power output for the first bout was 209 ± 3 s and 313 ± 10 W respectively. Recovery of mean power output was incomplete even after 6 min (78 ± 2, 81 ± 2 and 84 ± 2% for INT1.5, INT3 and INT6 respectively). Mean power output after INT6 was higher (p < 0.01) only compared with INT1.5. Power output during the first 500 m of bout 2 after INT6 was 10% higher compared with the second 500 m. During INT1.5 and INT3 power output during the first and the second 500 m of bout 2 was similar. Peak heart rate (∼197 b·min-1) and the HR time constant (∼13 s) were unaffected by prior exercise and recovery time. However, when the recovery was short (INT1.5), HR during the first 50 s of bout 2 was significantly higher compared with corresponding values during bout 1. The present study has shown that in order to maintain similar power outputs during repeated maximal rowing exercise, the recovery interval must be greater than 6 min. The influence of a longer recovery time (INT6) on maintenance of power output was only evident during the first half of the second 1000 m bout. ©Journal of Sports Science and Medicine.

{The aim of this study was to explore and compare the magnitude and time-course of the shift in the angle-force curves obtained from maximal voluntary contractions of the elbow flexors, both before and 4 consecutive days after eccentric and isometric exercise. The maximal isometric force of the elbow flexors of fourteen young male volunteers was measured at five different elbow angles between 50° and 160°. Subjects were then divided into two groups: The eccentric group (ECC

The purpose of this study was to examine the influence of a carbohydrate-rich meal on post-prandial metabolic responses and skeletal muscle glycogen concentration. After an overnight fast, eight male recreational/club endurance runners ingested a carbohydrate (CHO) meal (2.5 g CHO - kg-1 body mass) and biopsies were obtained from the vastus lateralis muscle before and 3 h after the meal. Ingestion of the meal resulted in a 10.6 ± 2.5% (P < 0.05) increase in muscle glycogen concentration (pre-meal vs post-meal: 314.0 ± 33.9 vs 347.3 ± 31.3 mmol · kg-1 dry weight). Three hours after ingestion, mean serum insulin concentrations had not returned to pre-feeding values (0 min vs 180 min: 45 ± 4 vs 143 ± 21 pmol · 1-1). On a separate occasion, six similar individuals ingested the meal or fasted for a further 3 h during which time expired air samples were collected to estimate the amount of carbohydrate oxidized over the 3 h post-prandial period. It was estimated that about 20% of the carbohydrate consumed was converted into muscle glycogen, and about 12% was oxidized. We conclude that a meal providing 2.5 g CHO · kg-1 body mass can increase muscle glycogen stores 3 h after ingestion. However, an estimated 67% of the carbohydrate ingested was unaccounted for and this may have been stored as liver glycogen and/or still be in the gastrointestinal tract. © 2004 Taylor & Francis Ltd.

{The aim of this study was to explore and compare the magnitude and time-course of the shift in the angle-force curves obtained from maximal voluntary contractions of the elbow flexors, both before and 4 consecutive days after eccentric and isometric exercise. The maximal isometric force of the elbow flexors of fourteen young male volunteers was measured at five different elbow angles between 50° and 160°. Subjects were then divided into two groups: The eccentric group (ECC

The purpose of this study was to examine the influence of a carbohydrate-rich meal on post-prandial metabolic responses and skeletal muscle glycogen concentration. After an overnight fast, eight male recreational/club endurance runners ingested a carbohydrate (CHO) meal (2.5 g CHO - kg-1 body mass) and biopsies were obtained from the vastus lateralis muscle before and 3 h after the meal. Ingestion of the meal resulted in a 10.6 ± 2.5% (P < 0.05) increase in muscle glycogen concentration (pre-meal vs post-meal: 314.0 ± 33.9 vs 347.3 ± 31.3 mmol · kg-1 dry weight). Three hours after ingestion, mean serum insulin concentrations had not returned to pre-feeding values (0 min vs 180 min: 45 ± 4 vs 143 ± 21 pmol · 1-1). On a separate occasion, six similar individuals ingested the meal or fasted for a further 3 h during which time expired air samples were collected to estimate the amount of carbohydrate oxidized over the 3 h post-prandial period. It was estimated that about 20% of the carbohydrate consumed was converted into muscle glycogen, and about 12% was oxidized. We conclude that a meal providing 2.5 g CHO · kg-1 body mass can increase muscle glycogen stores 3 h after ingestion. However, an estimated 67% of the carbohydrate ingested was unaccounted for and this may have been stored as liver glycogen and/or still be in the gastrointestinal tract. © 2004 Taylor & Francis Ltd.

The aim of this study was to explore and compare the magnitude and time-course of the shift in the angle-force curves obtained from maximal voluntary contractions of the elbow flexors, both before and 4 consecutive days after eccentric and isometric exercise. The maximal isometric force of the elbow flexors of fourteen young male volunteers was measured at five different elbow angles between 50° and 160°. Subjects were then divided into two groups: The eccentric group (ECC, n = 7) and the isometric group (ISO, n = 7). Subjects in the ECC group performed 50 maximal voluntary eccentric contractions of the elbow flexors on an isokinetic dynamometer (30°. s-1), while subjects in the ISO group performed 50 maximal voluntary isometric muscle contractions with the elbow flexors at a lengthened position. Following the ECC and ISO exercise protocols, maximal isometric force at the five angles, muscle soreness, and the relaxed (RANG) and flexed (FANG) elbow angles were measured at 24 h intervals for 4 days. All results were presented as the mean and standard error, and a quadratic curve was used to model the maximal isometric force data obtained at the five elbow angles. This approach not only allowed us to mathematically describe the angle-force curves and estimate the peak force and optimum angle for peak force generation, but also enabled us to statistically compare the shift of the angle-force curves between and within groups. A large and persistent shift of the angle-force curve towards longer muscle lengths was observed 1 day after eccentric exercise (P<0.01). This resulted in a ∼16° shift of the optimum angle for force generation, which remained unchanged for the whole observation period. A smaller but also persistent shift of the angle-force curve was seen after isometric exercise at long muscle length (P<0.05; shift in optimum angle ∼5°). ECC exercise caused more muscle damage than ISO exercise, as indicated by the greater changes in RANG and ratings of muscle soreness (P<0.05). It was suggested that the shift in the angle-force curve was proportional to the degree of muscle damage and may be explained by the presence of overstretched sarcomeres that increased in series compliance of the muscle. © Springer-Verlag 2004.

The purpose of this study was to examine the influence of a carbohydrate-rich meal on post-prandial metabolic responses and skeletal muscle glycogen concentration. After an overnight fast, eight male recreational/club endurance runners ingested a carbohydrate (CHO) meal (2.5 g CHO - kg-1 body mass) and biopsies were obtained from the vastus lateralis muscle before and 3 h after the meal. Ingestion of the meal resulted in a 10.6 ± 2.5% (P < 0.05) increase in muscle glycogen concentration (pre-meal vs post-meal: 314.0 ± 33.9 vs 347.3 ± 31.3 mmol · kg-1 dry weight). Three hours after ingestion, mean serum insulin concentrations had not returned to pre-feeding values (0 min vs 180 min: 45 ± 4 vs 143 ± 21 pmol · 1-1). On a separate occasion, six similar individuals ingested the meal or fasted for a further 3 h during which time expired air samples were collected to estimate the amount of carbohydrate oxidized over the 3 h post-prandial period. It was estimated that about 20% of the carbohydrate consumed was converted into muscle glycogen, and about 12% was oxidized. We conclude that a meal providing 2.5 g CHO · kg-1 body mass can increase muscle glycogen stores 3 h after ingestion. However, an estimated 67% of the carbohydrate ingested was unaccounted for and this may have been stored as liver glycogen and/or still be in the gastrointestinal tract. © 2004 Taylor & Francis Ltd.

In this study, we examined the long-term reductions in maximal isometric force (MIF) caused by a protocol of repeated maximal isometric contractions at long muscle length. Furthermore, we wished to ascertain whether the reductions in MIF are dependent on muscle length - that is, are the reductions in MIF more pronounced when the muscle contracts at a short length. The MIF of the elbow flexors of seven young male volunteers was measured at five different elbow angles between 50° and 160°. On a separate day, the participants performed 50 maximal voluntary isometric muscle contractions with the elbow flexors at a lengthened position; that is, with the shoulder hyperextended at 45° and the elbow joint fixed at 140°. Following this exercise, the MIF at the five elbow angles, range of motion, muscle soreness and plasma creatine kinase activity were measured at 24 h intervals for 4 days. On day 1, the decline in MIF was higher at the more acute elbow angles of 50° (42 ± 8%) and 70° (39 ± 8%; both P < 0.01) than at 90° (26 ± 4%) and 140° (16 ± 3%; both P < 0.01). No significant reduction in MIF was evident at an elbow angle of 160°. Maximal isometric force at an elbow angle of 140° was fully restored on day 3, whereas at an angle of 50° it remained depressed for the 4 day observation period. Restoration of MIF was a function of the elbow angle, with force recovery being less at the smaller angles. The range of motion was decreased by 14 ± 2° on day 1 (P < 0.01) and did not return to baseline values by day 4. Muscle soreness ratings remained significantly elevated for the 4 day period. Serum creatine kinase peaked on day 1 (522 ± 129 IU, P < 0.01) and decreased thereafter. We conclude that the disproportionate decrease in MIF at the small elbow angles and the length-specific recovery in MIF after repeated maximal isometric contractions at long muscle length may be explained by the presence of overstretched sarcomeres that increased in series compliance of the muscle, therefore causing a rightward shift of the force-length relationship.

In this study, we examined the long-term reductions in maximal isometric force (MIF) caused by a protocol of repeated maximal isometric contractions at long muscle length. Furthermore, we wished to ascertain whether the reductions in MIF are dependent on muscle length - that is, are the reductions in MIF more pronounced when the muscle contracts at a short length. The MIF of the elbow flexors of seven young male volunteers was measured at five different elbow angles between 50° and 160°. On a separate day, the participants performed 50 maximal voluntary isometric muscle contractions with the elbow flexors at a lengthened position; that is, with the shoulder hyperextended at 45° and the elbow joint fixed at 140°. Following this exercise, the MIF at the five elbow angles, range of motion, muscle soreness and plasma creatine kinase activity were measured at 24 h intervals for 4 days. On day 1, the decline in MIF was higher at the more acute elbow angles of 50° (42 ± 8%) and 70° (39 ± 8%; both P < 0.01) than at 90° (26 ± 4%) and 140° (16 ± 3%; both P < 0.01). No significant reduction in MIF was evident at an elbow angle of 160°. Maximal isometric force at an elbow angle of 140° was fully restored on day 3, whereas at an angle of 50° it remained depressed for the 4 day observation period. Restoration of MIF was a function of the elbow angle, with force recovery being less at the smaller angles. The range of motion was decreased by 14 ± 2° on day 1 (P < 0.01) and did not return to baseline values by day 4. Muscle soreness ratings remained significantly elevated for the 4 day period. Serum creatine kinase peaked on day 1 (522 ± 129 IU, P < 0.01) and decreased thereafter. We conclude that the disproportionate decrease in MIF at the small elbow angles and the length-specific recovery in MIF after repeated maximal isometric contractions at long muscle length may be explained by the presence of overstretched sarcomeres that increased in series compliance of the muscle, therefore causing a rightward shift of the force-length relationship.

In this study, we examined the long-term reductions in maximal isometric force (MIF) caused by a protocol of repeated maximal isometric contractions at long muscle length. Furthermore, we wished to ascertain whether the reductions in MIF are dependent on muscle length - that is, are the reductions in MIF more pronounced when the muscle contracts at a short length. The MIF of the elbow flexors of seven young male volunteers was measured at five different elbow angles between 50° and 160°. On a separate day, the participants performed 50 maximal voluntary isometric muscle contractions with the elbow flexors at a lengthened position; that is, with the shoulder hyperextended at 45° and the elbow joint fixed at 140°. Following this exercise, the MIF at the five elbow angles, range of motion, muscle soreness and plasma creatine kinase activity were measured at 24 h intervals for 4 days. On day 1, the decline in MIF was higher at the more acute elbow angles of 50° (42 ± 8%) and 70° (39 ± 8%; both P < 0.01) than at 90° (26 ± 4%) and 140° (16 ± 3%; both P < 0.01). No significant reduction in MIF was evident at an elbow angle of 160°. Maximal isometric force at an elbow angle of 140° was fully restored on day 3, whereas at an angle of 50° it remained depressed for the 4 day observation period. Restoration of MIF was a function of the elbow angle, with force recovery being less at the smaller angles. The range of motion was decreased by 14 ± 2° on day 1 (P < 0.01) and did not return to baseline values by day 4. Muscle soreness ratings remained significantly elevated for the 4 day period. Serum creatine kinase peaked on day 1 (522 ± 129 IU, P < 0.01) and decreased thereafter. We conclude that the disproportionate decrease in MIF at the small elbow angles and the length-specific recovery in MIF after repeated maximal isometric contractions at long muscle length may be explained by the presence of overstretched sarcomeres that increased in series compliance of the muscle, therefore causing a rightward shift of the force-length relationship.

We examined the plasma concentration curve obtained over 6 h after the ingestion of 2 g of creatine (Cr) (equivalent to 2.3 g Cr·H2O) contained in meat or in solution in five non-users of creatine supplements. Peak plasma creatine concentration was lower after the ingestion of meat but was maintained close to this for a longer period. Measurements of the area under the plasma concentration curve indicated approximate bioequivalence of creatine contained in meat with the same dose supplied in a solution. In a separate study, we examined the plasma concentration-time curve after ingestion of solid Cr·H2O. Creatine ingested as a lozenge (crushed in the mouth and swallowed) or as a crystalline suspension in ice cold water resulted in a 20% lower peak concentration and 30-35% smaller area under the plasma creatine concentration curve than the same dose administered in solution. Despite a possibly lower bioavailability, 2.3 g Cr·H2O supplied in either solid form was nonetheless sufficient to raise the plasma concentration five- to six-fold in individuals with a mean body mass of 75.6 kg. We conclude that creatine administered as meat or in solid form is readily absorbed but may result in sligthly lower peak concentrations than when the same dose is ingested as a solution.

We examined the plasma concentration curve obtained over 6 h after the ingestion of 2 g of creatine (Cr) (equivalent to 2.3 g Cr·H2O) contained in meat or in solution in five non-users of creatine supplements. Peak plasma creatine concentration was lower after the ingestion of meat but was maintained close to this for a longer period. Measurements of the area under the plasma concentration curve indicated approximate bioequivalence of creatine contained in meat with the same dose supplied in a solution. In a separate study, we examined the plasma concentration-time curve after ingestion of solid Cr·H2O. Creatine ingested as a lozenge (crushed in the mouth and swallowed) or as a crystalline suspension in ice cold water resulted in a 20% lower peak concentration and 30-35% smaller area under the plasma creatine concentration curve than the same dose administered in solution. Despite a possibly lower bioavailability, 2.3 g Cr·H2O supplied in either solid form was nonetheless sufficient to raise the plasma concentration five- to six-fold in individuals with a mean body mass of 75.6 kg. We conclude that creatine administered as meat or in solid form is readily absorbed but may result in sligthly lower peak concentrations than when the same dose is ingested as a solution.

We examined the plasma concentration curve obtained over 6 h after the ingestion of 2 g of creatine (Cr) (equivalent to 2.3 g Cr·H2O) contained in meat or in solution in five non-users of creatine supplements. Peak plasma creatine concentration was lower after the ingestion of meat but was maintained close to this for a longer period. Measurements of the area under the plasma concentration curve indicated approximate bioequivalence of creatine contained in meat with the same dose supplied in a solution. In a separate study, we examined the plasma concentration-time curve after ingestion of solid Cr·H2O. Creatine ingested as a lozenge (crushed in the mouth and swallowed) or as a crystalline suspension in ice cold water resulted in a 20% lower peak concentration and 30-35% smaller area under the plasma creatine concentration curve than the same dose administered in solution. Despite a possibly lower bioavailability, 2.3 g Cr·H2O supplied in either solid form was nonetheless sufficient to raise the plasma concentration five- to six-fold in individuals with a mean body mass of 75.6 kg. We conclude that creatine administered as meat or in solid form is readily absorbed but may result in sligthly lower peak concentrations than when the same dose is ingested as a solution.

On two separate days eight male subjects performed a 10- or 20-s cycle ergometer sprint (randomized order) followed, after 2 min of recovery, by a 30-s sprint. Muscle biopsies were obtained from the vastus lateralis at rest, immediately after the first sprint and after the 2 min of recovery on both occasions. The anaerobic ATP turnover during the initial 10 s of sprint 1 was 129 ± 12 mmol kg dry weight-1 and decreased to 63 ± 10 mmol kg dry weight-1 between the 10th and 20th s of sprint 1. This was a result of a 300% decrease in the rate of phosphocreatine breakdown and a 35% decrease in the glycolytic rate. Despite this 51% reduction in anaerobic ATP turnover, the mean power between 10 and 20 s of sprint 1 was reduced by only 28%. During the same period, oxygen uptake increased from 1.30 ± 0.15 to 2.40 ± 0.23 L min-1, which partially compensated for the decreased anaerobic metabolism. Muscle pH decreased from 7.06 ± 0.02 at rest to 6.94 ± 0.02 after 10 s and 6.82 ± 0.03 after 20 s of sprinting (for all changes P < 0.01). Muscle pH did not change following a 2-min recovery period after both the 10- and 20-s sprints, but phosphocreatine was resynthesized to 86 ± 3 and 76 ± 3% of the resting value, respectively (n.s. 10- vs. 20-s sprint). Following 2 min of recovery after the 10-s sprint subjects were able to reproduce peak but not mean power. Restoration of both mean and peak power following the 20-s sprint was 88% of sprint 1, and was lower compared with that after the 10-s sprint (P < 0.01). Total work during the second 30-s sprint after the 10- and the 20-s sprint was 19.3 ± 0.6 and 17.8 ± 0.5 kJ, respectively (P < 0.01). As oxygen uptake was the same during the 30-s sprints (2.95 ± 0.15 and 3.02 ± 0.16 L min-1), and [Phosphocreatine] before the sprint was similar, the lower work may be related to a reduced glycolytic ATP regeneration as a result of the higher muscle acidosis.

On two separate days eight male subjects performed a 10- or 20-s cycle ergometer sprint (randomized order) followed, after 2 min of recovery, by a 30-s sprint. Muscle biopsies were obtained from the vastus lateralis at rest, immediately after the first sprint and after the 2 min of recovery on both occasions. The anaerobic ATP turnover during the initial 10 s of sprint 1 was 129 ± 12 mmol kg dry weight-1 and decreased to 63 ± 10 mmol kg dry weight-1 between the 10th and 20th s of sprint 1. This was a result of a 300% decrease in the rate of phosphocreatine breakdown and a 35% decrease in the glycolytic rate. Despite this 51% reduction in anaerobic ATP turnover, the mean power between 10 and 20 s of sprint 1 was reduced by only 28%. During the same period, oxygen uptake increased from 1.30 ± 0.15 to 2.40 ± 0.23 L min-1, which partially compensated for the decreased anaerobic metabolism. Muscle pH decreased from 7.06 ± 0.02 at rest to 6.94 ± 0.02 after 10 s and 6.82 ± 0.03 after 20 s of sprinting (for all changes P < 0.01). Muscle pH did not change following a 2-min recovery period after both the 10- and 20-s sprints, but phosphocreatine was resynthesized to 86 ± 3 and 76 ± 3% of the resting value, respectively (n.s. 10- vs. 20-s sprint). Following 2 min of recovery after the 10-s sprint subjects were able to reproduce peak but not mean power. Restoration of both mean and peak power following the 20-s sprint was 88% of sprint 1, and was lower compared with that after the 10-s sprint (P < 0.01). Total work during the second 30-s sprint after the 10- and the 20-s sprint was 19.3 ± 0.6 and 17.8 ± 0.5 kJ, respectively (P < 0.01). As oxygen uptake was the same during the 30-s sprints (2.95 ± 0.15 and 3.02 ± 0.16 L min-1), and [Phosphocreatine] before the sprint was similar, the lower work may be related to a reduced glycolytic ATP regeneration as a result of the higher muscle acidosis.

On two separate days eight male subjects performed a 10- or 20-s cycle ergometer sprint (randomized order) followed, after 2 min of recovery, by a 30-s sprint. Muscle biopsies were obtained from the vastus lateralis at rest, immediately after the first sprint and after the 2 min of recovery on both occasions. The anaerobic ATP turnover during the initial 10 s of sprint 1 was 129 ± 12 mmol kg dry weight-1 and decreased to 63 ± 10 mmol kg dry weight-1 between the 10th and 20th s of sprint 1. This was a result of a 300% decrease in the rate of phosphocreatine breakdown and a 35% decrease in the glycolytic rate. Despite this 51% reduction in anaerobic ATP turnover, the mean power between 10 and 20 s of sprint 1 was reduced by only 28%. During the same period, oxygen uptake increased from 1.30 ± 0.15 to 2.40 ± 0.23 L min-1, which partially compensated for the decreased anaerobic metabolism. Muscle pH decreased from 7.06 ± 0.02 at rest to 6.94 ± 0.02 after 10 s and 6.82 ± 0.03 after 20 s of sprinting (for all changes P < 0.01). Muscle pH did not change following a 2-min recovery period after both the 10- and 20-s sprints, but phosphocreatine was resynthesized to 86 ± 3 and 76 ± 3% of the resting value, respectively (n.s. 10- vs. 20-s sprint). Following 2 min of recovery after the 10-s sprint subjects were able to reproduce peak but not mean power. Restoration of both mean and peak power following the 20-s sprint was 88% of sprint 1, and was lower compared with that after the 10-s sprint (P < 0.01). Total work during the second 30-s sprint after the 10- and the 20-s sprint was 19.3 ± 0.6 and 17.8 ± 0.5 kJ, respectively (P < 0.01). As oxygen uptake was the same during the 30-s sprints (2.95 ± 0.15 and 3.02 ± 0.16 L min-1), and [Phosphocreatine] before the sprint was similar, the lower work may be related to a reduced glycolytic ATP regeneration as a result of the higher muscle acidosis.

A model for phosphocreatine (PCr) resynthesis is proposed based on a simple electric circuit, where the PCr store in muscle is likened to the stored charge on the capacitor. The solution to the second-order differential equation that describes the potential around the circuit suggests the model for PCr resynthesis is given by PCr(t) = R - [d1 · exp(-k1·t) ± d2·exp(-k2·t)], where R is PCr concentration at rest, d1, d2, k1, and k2 are constants, and t is time. By using nonlinear least squares regression, this double-exponential model was shown to fit the PCr recovery data taken from two studies involving maximal exercise accurately. In study 1, when the muscle was electrically stimulated while occluded, PCr concentrations rose during the recovery phase to a level above that observed at rest. In study 2, after intensive dynamic exercise, PCr recovered monotonically to resting concentrations. The second exponential term in the double-exponential model was found to make a significant additional contribution to the quality of fit in both study 1 (P < 0.05) and study 2 (P < 0.01).

A model for phosphocreatine (PCr) resynthesis is proposed based on a simple electric circuit, where the PCr store in muscle is likened to the stored charge on the capacitor. The solution to the second-order differential equation that describes the potential around the circuit suggests the model for PCr resynthesis is given by PCr(t) = R - [d1 · exp(-k1·t) ± d2·exp(-k2·t)], where R is PCr concentration at rest, d1, d2, k1, and k2 are constants, and t is time. By using nonlinear least squares regression, this double-exponential model was shown to fit the PCr recovery data taken from two studies involving maximal exercise accurately. In study 1, when the muscle was electrically stimulated while occluded, PCr concentrations rose during the recovery phase to a level above that observed at rest. In study 2, after intensive dynamic exercise, PCr recovered monotonically to resting concentrations. The second exponential term in the double-exponential model was found to make a significant additional contribution to the quality of fit in both study 1 (P < 0.05) and study 2 (P < 0.01).

A model for phosphocreatine (PCr) resynthesis is proposed based on a simple electric circuit, where the PCr store in muscle is likened to the stored charge on the capacitor. The solution to the second-order differential equation that describes the potential around the circuit suggests the model for PCr resynthesis is given by PCr(t) = R - [d 1 · exp(-k 1·t) ± d 2·exp(-k 2·t)], where R is PCr concentration at rest, d 1, d 2, k 1, and k 2 are constants, and t is time. By using nonlinear least squares regression, this double-exponential model was shown to fit the PCr recovery data taken from two studies involving maximal exercise accurately. In study 1, when the muscle was electrically stimulated while occluded, PCr concentrations rose during the recovery phase to a level above that observed at rest. In study 2, after intensive dynamic exercise, PCr recovered monotonically to resting concentrations. The second exponential term in the double-exponential model was found to make a significant additional contribution to the quality of fit in both study 1 (P < 0.05) and study 2 (P < 0.01).

This study examined the contribution of phosphocreatine (PCr) and aerobic metabolism during repeated bouts of sprint exercise. Eight male subjects performed two cycle ergometer sprints separated by 4 min of recovery during two separate main trials. Sprint 1 lasted 30 s during both main trials, whereas sprint 2 lasted either 10 or 30 s. Muscle biopsies were obtained at rest, immediately after the first 30-s sprint, after 3.8 min of recovery, and after the second 10-and 30-s sprints. At the end of sprint 1, PCr was 16.9 ± 1.4% of the resting value, and muscle pH dropped to 6.69 ± 0.02. After 3.8 min of recovery, muscle pH remained unchanged (6.80 ± 0.03), but PCr was resynthesized to 78.7 ± 3.3% of the resting value. PCr during sprint 2 was almost completely utilized in the first 10 s and remained unchanged thereafter. High correlations were found between the percentage of PCr resynthesis and the percentage recovery of power output and pedaling speed during the initial 10 s of sprint 2 (r = 0.84, P < 0.05 and r = 0.91, P < 0.01). The anaerobic ATP turnover, as calculated from changes in ATP, PCr, and lactate, was 235 ± 9 mmol/kg dry muscle during the first sprint but was decreased to 139 ± 7 mmol/kg dry muscle during the second 30-s sprint, mainly as a result of a  45% decrease in glycolysis. Despite this  41% reduction in anaerobic energy, the total work done during the second 30-s sprint was reduced by only  18%. This mismatch between anaerobic energy release and power output during sprint 2 was partly compensated for by an increased contribution of aerobic metabolism, as calculated from the increase in oxygen uptake during sprint 2 (2.68 ± 0.10 vs. 3.17 ± 0.13 l/min; sprint 1 vs. sprint 2; P < 0.01). These data suggest that aerobic metabolism provides a significant part ( 49%) of the energy during the second sprint, whereas PCr availability is important for high power output during the initial 10 s.

This study examined the contribution of phosphocreatine (PCr) and aerobic metabolism during repeated bouts of sprint exercise. Eight male subjects performed two cycle ergometer sprints separated by 4 min of recovery during two separate main trials. Sprint 1 lasted 30 s during both main trials, whereas sprint 2 lasted either 10 or 30 s. Muscle biopsies were obtained at rest, immediately after the first 30-s sprint, after 3.8 min of recovery, and after the second 10-and 30-s sprints. At the end of sprint 1, PCr was 16.9 ± 1.4% of the resting value, and muscle pH dropped to 6.69 ± 0.02. After 3.8 min of recovery, muscle pH remained unchanged (6.80 ± 0.03), but PCr was resynthesized to 78.7 ± 3.3% of the resting value. PCr during sprint 2 was almost completely utilized in the first 10 s and remained unchanged thereafter. High correlations were found between the percentage of PCr resynthesis and the percentage recovery of power output and pedaling speed during the initial 10 s of sprint 2 (r = 0.84, P < 0.05 and r = 0.91, P < 0.01). The anaerobic ATP turnover, as calculated from changes in ATP, PCr, and lactate, was 235 ± 9 mmol/kg dry muscle during the first sprint but was decreased to 139 ± 7 mmol/kg dry muscle during the second 30-s sprint, mainly as a result of a  45% decrease in glycolysis. Despite this  41% reduction in anaerobic energy, the total work done during the second 30-s sprint was reduced by only  18%. This mismatch between anaerobic energy release and power output during sprint 2 was partly compensated for by an increased contribution of aerobic metabolism, as calculated from the increase in oxygen uptake during sprint 2 (2.68 ± 0.10 vs. 3.17 ± 0.13 l/min; sprint 1 vs. sprint 2; P < 0.01). These data suggest that aerobic metabolism provides a significant part ( 49%) of the energy during the second sprint, whereas PCr availability is important for high power output during the initial 10 s.

The effects of active recovery on metabolic and cardiorespiratory responses and power output were examined during repeated sprints. Male subjects (n = 13) performed two maximal 30-s cycle ergometer sprints, 4 min apart, on two separate occasions with either an active [cycling at 40 (1)% of maximal oxygen uptake; mean (SEM)] or passive recovery. Active recovery resulted in a significantly higher mean power output (W̄) during sprint 2, compared with passive recovery [W̄] 603 (17) W and 589 (15) W, P < 0.05]. This improvement was totally attributed to a 3.1 (1.0)% higher power generation during the initial 10 s of sprint 2 following the active recovery (P < 0.05), since power output during the last 20 s sprint 2 was the same after both recoveries. Despite the higher power output during sprint 2 after active recovery, no differences were observed between conditions in venous blood lactate and pH, but peak plasma ammonia was significantly higher in the active recovery condition [205 (23) vs 170 (20) μmol·l-1; P < 0.05]. No differences were found between active and passive recovery in terms of changes in plasma volume or arterial blood pressure throughout the test. However, heart rate between the two 30-s sprints and oxygen uptake during the second sprint were higher for the active compared with passive recovery [148 (3) vs 130 (4) beats min-1; P < 0.01) and 3.3 (0.1) vs 2.8 (0.1) l·min-1; P < 0.01]. These data suggest that recovery of power output during repeated sprint exercise is enhanced when low-intensity exercise is performed between sprints. The beneficial effects of an active recovery are possibly mediated by an increased blood flow to the previously exercised muscle.

This study examined the contribution of phosphocreatine (PCr) and aerobic metabolism during repeated bouts of sprint exercise. Eight male subjects performed two cycle ergometer sprints separated by 4 min of recovery during two separate main trials. Sprint 1 lasted 30 s during both main trials, whereas sprint 2 lasted either 10 or 30 s. Muscle biopsies were obtained at rest, immediately after the first 30-s sprint, after 3.8 min of recovery, and after the second 10-and 30-s sprints. At the end of sprint 1, PCr was 16.9 ± 1.4% of the resting value, and muscle pH dropped to 6.69 ± 0.02. After 3.8 min of recovery, muscle pH remained unchanged (6.80 ± 0.03), but PCr was resynthesized to 78.7 ± 3.3% of the resting value. PCr during sprint 2 was almost completely utilized in the first 10 s and remained unchanged thereafter. High correlations were found between the percentage of PCr resynthesis and the percentage recovery of power output and pedaling speed during the initial 10 s of sprint 2 (r = 0.84, P < 0.05 and r = 0.91, P < 0.01). The anaerobic ATP turnover, as calculated from changes in ATP, PCr, and lactate, was 235 ± 9 mmol/kg dry muscle during the first sprint but was decreased to 139 ± 7 mmol/kg dry muscle during the second 30-s sprint, mainly as a result of a ~45% decrease in glycolysis. Despite this ~41% reduction in anaerobic energy, the total work done during the second 30-s sprint was reduced by only ~18%. This mismatch between anaerobic energy release and power output during sprint 2 was partly compensated for by an increased contribution of aerobic metabolism, as calculated from the increase in oxygen uptake during sprint 2 (2.68 ± 0.10 vs. 3.17 ± 0.13 l/min; sprint 1 vs. sprint 2; P < 0.01). These data suggest that aerobic metabolism provides a significant part (~49%) of the energy during the second sprint, whereas PCr availability is important for high power output during the initial 10 s.

The effects of active recovery on metabolic and cardiorespiratory responses and power output were examined during repeated sprints. Male subjects (n = 13) performed two maximal 30-s cycle ergometer sprints, 4 min apart, on two separate occasions with either an active [cycling at 40 (1)% of maximal oxygen uptake; mean (SEM)] or passive recovery. Active recovery resulted in a significantly higher mean power output (W̄) during sprint 2, compared with passive recovery [W̄] 603 (17) W and 589 (15) W, P < 0.05]. This improvement was totally attributed to a 3.1 (1.0)% higher power generation during the initial 10 s of sprint 2 following the active recovery (P < 0.05), since power output during the last 20 s sprint 2 was the same after both recoveries. Despite the higher power output during sprint 2 after active recovery, no differences were observed between conditions in venous blood lactate and pH, but peak plasma ammonia was significantly higher in the active recovery condition [205 (23) vs 170 (20) μmol·l-1; P < 0.05]. No differences were found between active and passive recovery in terms of changes in plasma volume or arterial blood pressure throughout the test. However, heart rate between the two 30-s sprints and oxygen uptake during the second sprint were higher for the active compared with passive recovery [148 (3) vs 130 (4) beats min-1; P < 0.01) and 3.3 (0.1) vs 2.8 (0.1) l·min-1; P < 0.01]. These data suggest that recovery of power output during repeated sprint exercise is enhanced when low-intensity exercise is performed between sprints. The beneficial effects of an active recovery are possibly mediated by an increased blood flow to the previously exercised muscle.

1. The recovery of power output and muscle metabolites was examined following maximal sprint cycling exercise. Fourteen male subjects performed two 30 s cycle ergometer sprints separated by 1.5, 3 and 6 min of recovery, on three separate occasions. On a fourth occasion eight of the subjects performed only one 30 s sprint and muscle biopsies were obtained during recovery. 2. At the end of the 30 s sprint phosphocreatine (PCr) and ATP contents were 19.7 ± 1.2 and 70.5 ± 6.5% of the resting values (rest), respectively, while muscle lactate was 119.0 ± 4.6 mmol (kg dry wt)-1 and muscle pH was 6.72 ± 0.06. During recovery, PCr increased rapidly to 65.0 ± 2.8% of rest after 1.5 min, but reached only 85.5 ± 3.5% of rest after 6 min of recovery. At the same time ATP and muscle pH remained low (19.5 ± 0.9 mmol (kg dry wt)-1 and 6.79 ± 0.02, respectively). Modelling of the individual PCr resynthesis using a power function curve gave an average half-time for PCr resynthesis of 56.6 ± 7.3 s. 3. Recovery of peak power output (PPO), peak pedal speed (maxSp) and mean power during the initial 6 s (MPO6) of sprint 2 did not reach the control values after 6 min of rest, and occurred in parallel with the resynthesis of PCr, despite the low muscle pH. High correlations (r = 0.71-0.86; P < 0.05) were found between the percentage resynthesis of PCr and the percentage restoration of PPO, maxSp and MPO6 after 1.5 and 3 min of recovery. No relationship was observed between muscle pH recovery and power output restoration during sprint 2 (P > 0.05). 4. These data suggest that PCr resynthesis after 30 s of maximal sprint exercise is slower than previously observed after dynamic exercise of longer duration, and PCr resynthesis is important for the recovery of power during repeated bouts of sprint exercise.

1. The recovery of power output and muscle metabolites was examined following maximal sprint cycling exercise. Fourteen male subjects performed two 30 s cycle ergometer sprints separated by 1.5, 3 and 6 min of recovery, on three separate occasions. On a fourth occasion eight of the subjects performed only one 30 s sprint and muscle biopsies were obtained during recovery. 2. At the end of the 30 s sprint phosphocreatine (PCr) and ATP contents were 19.7 ± 1.2 and 70.5 ± 6.5% of the resting values (rest), respectively, while muscle lactate was 119.0 ± 4.6 mmol (kg dry wt)-1 and muscle pH was 6.72 ± 0.06. During recovery, PCr increased rapidly to 65.0 ± 2.8% of rest after 1.5 min, but reached only 85.5 ± 3.5% of rest after 6 min of recovery. At the same time ATP and muscle pH remained low (19.5 ± 0.9 mmol (kg dry wt)-1 and 6.79 ± 0.02, respectively). Modelling of the individual PCr resynthesis using a power function curve gave an average half-time for PCr resynthesis of 56.6 ± 7.3 s. 3. Recovery of peak power output (PPO), peak pedal speed (maxSp) and mean power during the initial 6 s (MPO6) of sprint 2 did not reach the control values after 6 min of rest, and occurred in parallel with the resynthesis of PCr, despite the low muscle pH. High correlations (r = 0.71-0.86; P < 0.05) were found between the percentage resynthesis of PCr and the percentage restoration of PPO, maxSp and MPO6 after 1.5 and 3 min of recovery. No relationship was observed between muscle pH recovery and power output restoration during sprint 2 (P > 0.05). 4. These data suggest that PCr resynthesis after 30 s of maximal sprint exercise is slower than previously observed after dynamic exercise of longer duration, and PCr resynthesis is important for the recovery of power during repeated bouts of sprint exercise.

1. The recovery of power output and muscle metabolites was examined following maximal sprint cycling exercise. Fourteen male subjects performed two 30 s cycle ergometer sprints separated by 1.5, 3 and 6 min of recovery, on three separate occasions. On a fourth occasion eight of the subjects performed only one 30 s sprint and muscle biopsies were obtained during recovery. 2. At the end of the 30 s sprint phosphocreatine (PCr) and ATP contents were 19.7 ± 1.2 and 70.5 ± 6.5% of the resting values (rest), respectively, while muscle lactate was 119.0 ± 4.6 mmol (kg dry wt)-1 and muscle pH was 6.72 ± 0.06. During recovery, PCr increased rapidly to 65.0 ± 2.8% of rest after 1.5 min, but reached only 85.5 ± 3.5% of rest after 6 min of recovery. At the same time ATP and muscle pH remained low (19.5 ± 0.9 mmol (kg dry wt)-1 and 6.79 ± 0.02, respectively). Modelling of the individual PCr resynthesis using a power function curve gave an average half-time for PCr resynthesis of 56.6 ± 7.3 s. 3. Recovery of peak power output (PPO), peak pedal speed (maxSp) and mean power during the initial 6 s (MPO6) of sprint 2 did not reach the control values after 6 min of rest, and occurred in parallel with the resynthesis of PCr, despite the low muscle pH. High correlations (r = 0.71-0.86; P < 0.05) were found between the percentage resynthesis of PCr and the percentage restoration of PPO, maxSp and MPO6 after 1.5 and 3 min of recovery. No relationship was observed between muscle pH recovery and power output restoration during sprint 2 (P > 0.05). 4. These data suggest that PCr resynthesis after 30 s of maximal sprint exercise is slower than previously observed after dynamic exercise of longer duration, and PCr resynthesis is important for the recovery of power during repeated bouts of sprint exercise.

This study examined the effects of elevating blood lactate concentration by arm exercise on subsequent performance during repeated 30 s sprints with the legs. Eight male students performed two 30 s cycle ergometer sprints separated by 6 min of recovery, on two occasions. On one occasion the subjects performed only the two 30 s cycle ergometer sprints (‘legs’), while on the other occasion 5 min of heavy arm cranking preceded the two sprints (‘arms and legs’). Blood lactate concentration was determined from capillary samples at rest, after a standardized warm-up and 3 and 5 min following each exercise bout. In the ‘legs’ condition, the peak power output (PPO) and mean power output (MPO) in the second sprint were 92% (P< 0.05) and 85% (P<0.01) of the values attained during the first sprint, respectively. Prior arm exercise, which increased blood lactate to 11.0 ± 0.6 mM, had no effect on PPO and MPO during the first cycle ergometer sprint (a4% drop, n.s.). However, in the second sprint after prior arm exercise, PPO was 10% lower than the PPO attained during the corresponding sprint in the ‘legs’ condition (sprint 2 ‘arms and legs’ 963+42 W, sprint 2 ‘legs’ 1074 + 60 W, P<0.05), while MPO was better maintained (sprint 2 ‘arms and legs’ 517 + 17 W, sprint 2 ‘legs’ 549 + 24 W, N.s.). The rate of blood lactate accumulation after both cycle ergometer sprints was considerably decreased (by a 50%) when blood lactate levels were pre-elevated by arm crank exercise. It is suggested that the elevation of blood lactate levels by prior arm exercise can cause a significant drop in PPO of the second sprint by decreasing muscle buffering capacity and lactate/H+ efflux from the muscle. The less pronounced drop in MPO during the second sprint in the ‘arms and legs’ condition was assumed to be due to an increased aerobic contribution to energy supply. © 1994 E. & F.N. Spon.

This study examined the effects of elevating blood lactate concentration by arm exercise on subsequent performance during repeated 30 s sprints with the legs. Eight male students performed two 30 s cycle ergometer sprints separated by 6 min of recovery, on two occasions. On one occasion the subjects performed only the two 30 s cycle ergometer sprints (‘legs’), while on the other occasion 5 min of heavy arm cranking preceded the two sprints (‘arms and legs’). Blood lactate concentration was determined from capillary samples at rest, after a standardized warm-up and 3 and 5 min following each exercise bout. In the ‘legs’ condition, the peak power output (PPO) and mean power output (MPO) in the second sprint were 92% (P< 0.05) and 85% (P<0.01) of the values attained during the first sprint, respectively. Prior arm exercise, which increased blood lactate to 11.0 ± 0.6 mM, had no effect on PPO and MPO during the first cycle ergometer sprint (a4% drop, n.s.). However, in the second sprint after prior arm exercise, PPO was 10% lower than the PPO attained during the corresponding sprint in the ‘legs’ condition (sprint 2 ‘arms and legs’ 963+42 W, sprint 2 ‘legs’ 1074 + 60 W, P<0.05), while MPO was better maintained (sprint 2 ‘arms and legs’ 517 + 17 W, sprint 2 ‘legs’ 549 + 24 W, N.s.). The rate of blood lactate accumulation after both cycle ergometer sprints was considerably decreased (by a 50%) when blood lactate levels were pre-elevated by arm crank exercise. It is suggested that the elevation of blood lactate levels by prior arm exercise can cause a significant drop in PPO of the second sprint by decreasing muscle buffering capacity and lactate/H+ efflux from the muscle. The less pronounced drop in MPO during the second sprint in the ‘arms and legs’ condition was assumed to be due to an increased aerobic contribution to energy supply. © 1994 E. & F.N. Spon.

This study examined the effects of elevating blood lactate concentration by arm exercise on subsequent performance during repeated 30 s sprints with the legs. Eight male students performed two 30 s cycle ergometer sprints separated by 6 min of recovery, on two occasions. On one occasion the subjects performed only the two 30 s cycle ergometer sprints ('legs'), while on the other occasion 5 min of heavy arm cranking preceded the two sprints ('arms and legs'). Blood lactate concentration was determined from capillary samples at rest, after a standardized warm-up and 3 and 5 min following each exercise bout. In the 'legs' condition, the peak power output (PPO) and mean power output (MPO) in the second sprint were 92% (P < 0.05) and 85% (P < 0.01) of the values attained during the first sprint, respectively. Prior arm exercise, which increased blood lactate to 11.0 ± 0.6 mM, had no effect on PPO and MPO during the first cycle ergometer sprint (≃ 4% drop, N.S.). However, in the second sprint after prior arm exercise, PPO was 10% lower than the PPO attained during the corresponding sprint in the 'legs' condition (sprint 2 'arms and legs' 963 ± 42 W, sprint 2 'legs' 1074 ± 60 W, P < 0.05), while MPO was better maintained (sprint 2 'arms and legs' 517 ± 17 W, sprint 2 'legs' 549 ± 24 W, N.S.). The rate of blood lactate accumulation after both cycle ergometer sprints was considerably decreased (by ≃ 50%) when blood lactate levels were pre-elevated by arm crank exercise. It is suggested that the elevation of blood lactate levels by prior arm exercise can cause a significant drop in PPO of the second sprint by decreasing muscle buffering capacity and lactate/H+ efflux from the muscle. The less pronounced drop in MPO during the second sprint in the 'arms and legs' condition was assumed to be due to an increased aerobic contribution to energy supply.