Native Whey Induces Similar Post Exercise Muscle Anabolic Responses as Regular Whey, Despite Greater Leucinemia, in Elderly Individuals

OBJECTIVE

Elderly muscle seems less sensitive to the anabolic stimulus of a meal. Changes in blood concentrations of leucine are suggested as one important trigger of the anabolic response in muscle. The aim of this study was to investigate whether native whey protein, containing high amounts of leucine, may be a more potent stimulator of muscle protein synthesis (MPS) in elderly than regular whey protein (WPC-80) or milk.

DESIGN

Randomized controlled partial crossover.

SETTING

Norwegian School of Sport Sciences.

PARTICIPANTS

21 healthy elderly men and women (≥70 years).

INTERVENTION

Participants received either 20 g of WPC-80 and native whey (n = 11) on separate days in a crossover design, or milk (n = 10). Supplements were ingested immediately and two hours after a bout of lower body heavy-load resistance exercise.

MEASUREMENTS

Blood samples and muscle biopsies were collected to measure blood concentrations of amino acids by gas-chromatography mass spectrometry (GCMS), phosphorylation of p70S6K, 4E-BP1 and eEF-2 by immunoblotting and mixed muscle fractional synthetic rate (FSR) by use of [2H5]phenylalanine-infusion, GCMS and isotope-ratio mass spectrometry.

RESULTS

Native whey increased blood leucine concentrations more than WPC-80 (P < 0.05), but not p70S6K phosphorylation or mixed muscle FSR. Both whey supplements increased blood leucine concentrations (P < 0.01) and P70S6K phosphorylation more than milk (P = 0.014). Native whey reached higher mixed muscle FSR values than milk (P = 0.026) 1-3h after exercise.

CONCLUSIONS

Despite greater increases in blood leucine concentrations than WPC-80 and milk, native whey was only superior to milk concerning increases in MPS and phosphorylation of P70S6K during a 5-hour post-exercise period in elderly individuals.

Autophagy is induced by resistance exercise in young men, but unfolded protein response is induced regardless of age

AIM

Autophagy and unfolded protein response (UPR) appear to be important for skeletal muscle homoeostasis and may be altered by exercise. Our aim was to investigate the effects of resistance exercise and training on indicators of UPR and autophagy in healthy untrained young men (n = 12, 27 ± 4 years) and older men (n = 8, 61 ± 6 years) as well as in resistance-trained individuals (n = 15, 25 ± 5 years).

METHODS

Indicators of autophagy and UPR were investigated from the muscle biopsies after a single resistance exercise bout and after 21 weeks of resistance training.

RESULTS

Lipidated LC3II as an indicator of autophagosome content increased at 48 hours post-resistance exercise (P < .05) and after a resistance training period (P < .01) in untrained young men but not in older men. Several UPR_ER markers, typically induced by protein misfolding in endoplasmic reticulum, were increased at 48 hours post-resistance exercise in untrained young and older men (P < .05) but were unaltered after the 21-week resistance training period regardless of age. UPR was unchanged within the first few hours after the resistance exercise bout regardless of the training status. Changes in autophagy and UPR_ER indicators did not correlate with a resistance training-induced increase in muscle strength and size.

CONCLUSION

Autophagosome content is increased by resistance training in young previously untrained men, but this response may be blunted by ageing. However, unfolded protein response is induced by an unaccustomed resistance exercise bout in a delayed manner regardless of age.

Antioxidant-rich foods and response to altitude training: A randomized controlled trial in elite endurance athletes

High doses of isolated antioxidant supplements such as vitamin C and E have demonstrated the potential to blunt cellular adaptations to training. It is, however, unknown whether intake of high doses of antioxidants from foods has similar effects. Hence, the aim of the study was to investigate whether intake of antioxidant-rich foods affects adaptations to altitude training in elite athletes. In a randomized controlled trial, 31 national team endurance athletes (23 ± 5 years) ingested antioxidant-rich foods (n = 16) or eucaloric control foods (n = 15) daily during a 3-week altitude training camp (2320 m). Changes from baseline to post-altitude in hemoglobin mass (Hb_mass ; optimized CO rebreathing), maximal oxygen uptake (VO_2max ; n = 16) or 100 m swimming performance (n = 10), and blood parameters were compared between the groups. The antioxidant group significantly increased total intake of antioxidant-rich foods (~118%) compared to the control group during the intervention. The total study population improved VO_2max by 2.5% (1.7 mL/kg/min, P = .006) and Hb_mass by 4.7% (48 g, P < .001), but not 100 m swimming performance. No difference was found between the groups regarding changes in Hb_mass , VO_2max or swimming performance. However, hemoglobin concentration increased more in the antioxidant group (effect size = 0.7; P = .045) with a concomitantly larger decrease in plasma and blood volumes compared to control group. Changes in ferritin and erythropoietin from pre- to post-altitude did not differ between the groups. Doubling the intake of antioxidant-rich foods was well tolerated and did not negatively influence the adaptive response to altitude training in elite endurance athletes.

Vitamin C and E supplementation does not affect heat shock proteins or endogenous antioxidants in trained skeletal muscles during 12 weeks of strength training

Background

Supplementation with large doses of antioxidants, such as vitamin C and E, has been shown to blunt some adaptations to endurance training. The effects of antioxidant supplementation on adaptations to strength training is sparsely studied. Herein we investigated the effects of vitamin C and E supplementation on acute stress responses to exercise and adaptation to traditional heavy load strength training.

Methods

In a double blind placebo-controlled design, twenty-eight, young, trained males and females were randomly assigned to receive either vitamin C and E (C: 1000 mg, E: 235 mg, per day) or placebo supplements, and underwent strength training for 10 weeks. After five weeks, a subgroup conducted a strength training session to investigate acute stress responses. Muscle samples were obtained to investigate changes in stress responses and in proteins and mRNA related to the heat shock proteins (HSPs) or antioxidant enzymes.

Results

The acute responses to the exercise session revealed activation of the NFκB pathway indicated by degradation of IκBα in both groups. Vitamin C and E supplementation had, however, no effects on the acute stress responses. Furthermore, ten weeks of strength training did not change muscle αB-crystallin, HSP27, HSP70, GPx1 or mnSOD levels, with no influence of supplementation.

Conclusions

Our results showed that although vitamin C and E supplementation has been shown to interfere with training adaptations, it did not affect acute stress responses or long-term training adaptations in the HSPs or antioxidant enzymes in this study.

Electronic supplementary material

The online version of this article (doi:10.1186/s40795-017-0185-8) contains supplementary material, which is available to authorized users.

Intake of a Protein-Enriched Milk and Effects on Muscle Mass and Strength. A 12-Week Randomized Placebo Controlled Trial among Community-Dwelling Older Adults

OBJECTIVES

To investigate the effect of 20 g protein with breakfast and evening meal on muscle mass, muscle strength and functional performance in older adults.

DESIGN

A double-blinded randomized controlled study.

SETTING

Oslo and Akershus University College of Applied Sciences, Norway.

PARTICIPANTS

Healthy community-dwelling men and women (≥ 70 years) with reduced physical strength and/or performance.

INTERVENTION

Subjects were randomly assigned to receive either protein-enriched milk (2 x 0.4 L/d; protein group) or an isocaloric carbohydrate drink (2 x 0.4 L/d; control group) with breakfast and evening meal for 12 weeks.

MEASUREMENTS

The primary endpoints were muscle mass measured by dual X-ray absorptiometry, and tests of muscle strength (one repetition maximum test of chest press and leg press) and functional performance (handgrip strength, stair calimb and repeated chair rise).

RESULTS

In total, 438 subjects were screened, 50 subjects were randomized and 36 completed the study. Chest press improved significantly in the protein (1.3 kg (0.1-2.5), p=0.03) and the control group (1.5 kg (0.0-3.0), p=0.048), but with no difference between the groups (p=0.85). No significant change in leg press (p=0.93) or muscle mass (p=0.54) were observed between the protein and the control group. Nor did we observe any significant differences in the functional performance tests (p>0.05 for all tests) between the groups.

CONCLUSION

Increased protein intake (2 x 20 g/d) did not significantly improve muscle mass, muscle strength or functional performance in healthy older weight stable adults. Whether intake of > 20 g protein to each meal is necessary for preservation of muscle mass and strength in older adults should be further investigated in a larger study. This underscores the need for well-designed studies that can differentiate between the effect of protein intake and increased energy. This trial was registered at Clinicaltrials.gov (ID no. NCT02218333).

The effect of strength training on muscle cellular stress in prostate cancer patients on ADT

BACKGROUND

Androgen deprivation therapy (ADT) for prostate cancer (PCa) is associated with several side effects, including loss of muscle mass. Muscle atrophy is associated with reduced mitochondrial function and increased muscle cellular stress that may be counteracted by strength training. Thus, the aim of this study was to investigate the effect of strength training on mitochondrial proteins and indicators of muscle cellular stress in PCa patients on ADT.

METHODS

Men diagnosed with locally advanced PCa receiving ADT were randomised to a strength training group (STG) (n=16) or a control group (CG) (n=15) for 16 weeks. Muscle biopsies were collected pre- and post-intervention from the vastus lateralis muscle, and analysed for mitochondrial proteins (citrate synthase, cytochrome c oxidase subunit IV (COXIV), HSP60) and indicators of muscle cellular stress (heat shock protein (HSP) 70, alpha B-crystallin, HSP27, free ubiquitin, and total ubiquitinated proteins) using Western blot and ELISA.

RESULTS

No significant intervention effects were observed in any of the mitochondrial proteins or indicators of muscle cellular stress. However, within-group analysis revealed that the level of HSP70 was reduced in the STG and a tendency towards a reduction in citrate synthase levels was observed in the CG. Levels of total ubiquitinated proteins were unchanged in both groups.

CONCLUSION

Although reduced HSP70 levels indicated reduced muscle cellular stress in the STG, the lack of an intervention effect precluded any clear conclusions.

Vitamin C and E supplementation blunts increases in total lean body mass in elderly men after strength training

The aim of this study was to investigate the effects of vitamin C and E supplementation on changes in muscle mass (lean mass and muscle thickness) and strength during 12 weeks of strength training in elderly men. Thirty-four elderly males (60-81 years) were randomized to either an antioxidant group (500 mg of vitamin C and 117.5 mg vitamin E before and after training) or a placebo group following the same strength training program (three sessions per week). Body composition was assessed with dual-energy X-ray absorptiometry and muscle thickness by ultrasound imaging. Muscle strength was measured as one-repetition maximum (1RM). Total lean mass increased by 3.9% (95% confidence intervals: 3.0, 5.2) and 1.4% (0, 5.4) in the placebo and antioxidant groups, respectively, revealing larger gains in the placebo group (P = 0.04). Similarly, the thickness of m. rectus femoris increased more in the placebo group [16.2% (12.8, 24.1)] than in the antioxidant group [10.9% (9.8, 13.5); P = 0.01]. Increases of lean mass in trunk and arms, and muscle thickness of elbow flexors, did not differ significantly between groups. With no group differences, 1RM improved in the range of 15-21% (P < 0.001). In conclusion, high-dosage vitamin C and E supplementation blunted certain muscular adaptations to strength training in elderly men.

Strength training improves cycling performance, fractional utilization of VO2max and cycling economy in female cyclists

The purpose of this study was to investigate the effect of adding heavy strength training to well-trained female cyclists' normal endurance training on cycling performance. Nineteen female cyclists were randomly assigned to 11 weeks of either normal endurance training combined with heavy strength training (E+S, n = 11) or to normal endurance training only (E, n = 8). E+S increased one repetition maximum in one-legged leg press and quadriceps muscle cross-sectional area (CSA) more than E (P < 0.05), and improved mean power output in a 40-min all-out trial, fractional utilization of VO2 max and cycling economy (P < 0.05). The proportion of type IIAX-IIX muscle fibers in m. vastus lateralis was reduced in E+S with a concomitant increase in type IIA fibers (P < 0.05). No changes occurred in E. The individual changes in performance during the 40-min all-out trial was correlated with both change in IIAX-IIX fiber proportion (r = -0.63) and change in muscle CSA (r = 0.73). In conclusion, adding heavy strength training improved cycling performance, increased fractional utilization of VO2 max , and improved cycling economy. The main mechanisms behind these improvements seemed to be increased quadriceps muscle CSA and fiber type shifts from type IIAX-IIX toward type IIA.

Vitamin C and E supplementation alters protein signalling after a strength training session, but not muscle growth during 10 weeks of training

This study investigated the effects of vitamin C and E supplementation on acute responses and adaptations to strength training. Thirty-two recreationally strength-trained men and women were randomly allocated to receive a vitamin C and E supplement (1000 mg day(-1) and 235 mg day(-1), respectively), or a placebo, for 10 weeks. During this period the participants' training involved heavy-load resistance exercise four times per week. Muscle biopsies from m. vastus lateralis were collected, and 1 repetition maximum (1RM) and maximal isometric voluntary contraction force, body composition (dual-energy X-ray absorptiometry), and muscle cross-sectional area (magnetic resonance imaging) were measured before and after the intervention. Furthermore, the cellular responses to a single exercise session were assessed midway in the training period by measurements of muscle protein fractional synthetic rate and phosphorylation of several hypertrophic signalling proteins. Muscle biopsies were obtained from m. vastus lateralis twice before, and 100 and 150 min after, the exercise session (4 × 8RM, leg press and knee-extension). The supplementation did not affect the increase in muscle mass or the acute change in protein synthesis, but it hampered certain strength increases (biceps curl). Moreover, increased phosphorylation of p38 mitogen-activated protein kinase, Extracellular signal-regulated protein kinases 1 and 2 and p70S6 kinase after the exercise session was blunted by vitamin C and E supplementation. The total ubiquitination levels after the exercise session, however, were lower with vitamin C and E than placebo. We concluded that vitamin C and E supplementation interfered with the acute cellular response to heavy-load resistance exercise and demonstrated tentative long-term negative effects on adaptation to strength training.

Acute response and subcellular movement of HSP27, αB-crystallin and HSP70 in human skeletal muscle after blood-flow-restricted low-load resistance exercise

AIM

Heat-shock proteins (HSP) are important chaperones for stressed and damaged proteins. Low-load blood-flow-restricted resistance exercise (BFRE) is generally believed not to induce significant muscle damage, but is hitherto unverified with intracellular markers. Consequently, the aim of this study was to investigate the HSP response after BFRE in human skeletal muscle.

METHODS

Nine healthy volunteers performed five sets to failure of unilateral knee extension at 30% of 1RM with partial blood-flow restriction. The contralateral leg performed the same work with free blood flow. Muscle biopsies were collected before exercise, 1, 24 and 48 h after exercise and analysed for HSP27, αB-crystallin, HSP70, desmin, glycogen content and myosin heavy chain by immunohistochemistry, ELISA and western blotting.

RESULTS

One hour after exercise, HSP27 and αB-crystallin levels were reduced in the cytosolic and increased in the cytoskeletal fraction in the BFRE leg. HSP70 showed a delayed response and was increased over 48 h in the BFRE leg. Immunohistochemical analyses showed higher staining intensity of HSP70 in type 1 fibres in the BFRE leg at 24 and 48 h post-exercise. PAS staining showed decreased glycogen levels after BFRE, and interestingly, glycogen was still depleted 48 h after exercise in the same fibres displaying high HSP70 staining (type 1 fibres).

CONCLUSION

Translocation of HSP27 and αB-crystallin from cytosol to cytoskeletal structures indicates that cytoskeletal proteins are stressed during BFRE. However, overt signs of myofibrillar disruptions were not observed. Interestingly, the stress response was more pronounced in type 1 than in type 2 fibres and coincided with low glycogen levels.

An antioxidant and multivitamin supplement reduced improvements in VO₂max

The aim of this study was to investigate the effect of an antioxidant supplement on training induced changes in VO₂max in well-trained subjects. In a double-blinded placebo controlled design, a total of 40 amateur soccer players and 14 multi sports athletes were block-randomised into a placebo group or an antioxidant supplemented group (SUP). The SUP group consumed two commercially available antioxidant/vitamin supplements for 6 weeks according to manufacturer instructions (LifePak® Essentials Super A) and the placebo group took a similar amount of placebo tablets. Before and after the supplementation period, the athletes were tested for skin carotenoid score and VO₂max. During the supplementation period all subjects continued their normal training in the preparation phase of the season. Six week supplementation with the antioxidant vitamin/mineral supplement increased skin carotenoid score by 27 ± 6% while no change was observed in the placebo group. VO₂max increased by 5.6 ± 2.0% in the placebo group while no change was observed in the SUP group. The relative increase in VO₂max was significantly higher in the placebo group than in the SUP group. In conclusion, the antioxidant vitamin/mineral supplement used in this study seemed to reduce training efficiency indicated by the lack of increase in VO₂max in the SUP group.

Effect of range of motion in heavy load squatting on muscle and tendon adaptations

Manipulating joint range of motion during squat training may have differential effects on adaptations to strength training with implications for sports and rehabilitation. Consequently, the purpose of this study was to compare the effects of squat training with a short vs. a long range of motion. Male students (n = 17) were randomly assigned to 12 weeks of progressive squat training (repetition matched, repetition maximum sets) performed as either a) deep squat (0-120° of knee flexion); n = 8 (DS) or (b) shallow squat (0-60 of knee flexion); n = 9 (SS). Strength (1 RM and isometric strength), jump performance, muscle architecture and cross-sectional area (CSA) of the thigh muscles, as well as CSA and collagen synthesis in the patellar tendon, were assessed before and after the intervention. The DS group increased 1 RM in both the SS and DS with ~20 ± 3 %, while the SS group achieved a 36 ± 4 % increase in the SS, and 9 ± 2 % in the DS (P < 0.05). However, the main finding was that DS training resulted in superior increases in front thigh muscle CSA (4-7 %) compared to SS training, whereas no differences were observed in patellar tendon CSA. In parallel with the larger increase in front thigh muscle CSA, a superior increase in isometric knee extension strength at 75° (6 ± 2 %) and 105° (8 ± 1 %) knee flexion, and squat-jump performance (15 ± 3 %) were observed in the DS group compared to the SS group. Training deep squats elicited favourable adaptations on knee extensor muscle size and function compared to training shallow squats.

Expression of perilipins in human skeletal muscle in vitro and in vivo in relation to diet, exercise and energy balance

The perilipin proteins enclose intracellular lipid droplets. We describe the mRNA expression of the five perilipins in human skeletal muscle in relation to fatty acid supply, exercise and energy balance. We observed that all perilipins were expressed in skeletal muscle biopsies with the highest mRNA levels of perilipin 2, 4 and 5. Cultured myotubes predominantly expressed perilipin 2 and 3. In vitro, incubation of myotubes with fatty acids enhanced mRNA expression of perilipin 1, 2 and 4. In vivo, low fat diet increased mRNA levels of perilipin 3 and 4. Endurance training, but not strength training, enhanced the expression of perilipin 2 and 3. Perilipin 1 mRNA correlated positively with body fat mass, whereas none of the perilipins were associated with insulin sensitivity. In conclusion, all perilipins mRNAs were expressed in human skeletal muscle. Diet as well as endurance exercise modulated the expression of perilipins.

Strength training improves 5-min all-out performance following 185 min of cycling

To investigate the effects of heavy strength training on the mean power output in a 5-min all-out trial following 185 min of submaximal cycling at 44% of maximal aerobic power output in well-trained cyclists. Twenty well-trained cyclists were assigned to either usual endurance training combined with heavy strength training [E+S; n=11 (♂=11)] or to usual endurance training only [E; n=9 (♂=7, ♀=2)]. The strength training performed by E+S consisted of four lower body exercises [3 × 4-10 repetition maximum (RM)], which were performed twice a week for 12 weeks. E+S increased 1 RM in half-squat (P≤0.001), while no change occurred in E. E+S led to greater reductions than E in oxygen consumption, heart rate, blood lactate concentration, and rate of perceived exertion (P<0.05) during the last hour of the prolonged cycling. Further, E+S increased the mean power output during the 5-min all-out trial (from 371 ± 9 to 400 ± 13 W, P<0.05), while no change occurred in E. In conclusion, adding strength training to usual endurance training improves leg strength and 5-min all-out performance following 185 min of cycling in well-trained cyclists.

Heat shock protein translocation and expression response is attenuated in response to repeated eccentric exercise

AIM

This study hypothesized that heat shock protein (HSP) translocation and upregulation is more probable to occur after eccentric exercise than after concentric exercise or repeated eccentric exercise.

METHODS

Fourteen young, healthy, untrained male subjects completed two bench-stepping exercise bouts with 8 weeks between bouts, and were compared with a control group (n = 6). Muscle biopsies collected from m. vastus lateralis of both legs prior to and at 3 h, 24 h and 7 days after exercise were quantified for mRNA levels and/or for HSP27, alphabeta-crystallin and inducible HSP70 content in cytosolic and cytoskeletal protein fractions.

RESULTS

The first bout of exercise reduced muscle strength and increased muscle soreness predominantly in the eccentric leg (P < 0.05). These responses were attenuated after the repeated eccentric exercise bout (P < 0.05), suggesting a repeated bout adaptation. Increases in inducible HSP70 and HSP27 protein content in cytoskeletal fractions were observed exclusively after eccentric exercise (P < 0.05). For HSP27, an approx. 10-fold upregulation after first-bout eccentric exercise was attenuated to a an approximately fourfold upregulation after the repeated eccentric exercise bout. mRNA levels for HSP70, HSP27 and alphabeta-crystallin were upregulated within approximately two to fourfold ranges at time points 3 and 24 h post-exercise (P < 0.05). This upregulation was induced exclusively by eccentric exercise but with a tendency to attenuated expression 3 h after the repeated eccentric exercise bout.

CONCLUSION

Our results show that HSP translocation and expression responses are induced by muscle damaging exercise, and suggest that such HSP responses are closely related to the extent of muscle damage.

Subcellular movement and expression of HSP27, alphaB-crystallin, and HSP70 after two bouts of eccentric exercise in humans

The aims of this study were to investigate the sarcomeric accumulation and expression of heat shock proteins (HSPs) after two bouts of maximal eccentric exercise. Twenty-four subjects performed two bouts of 70 maximal voluntary eccentric actions using the elbow flexors in one arm. The bouts were separated by 3 wk. The changes in concentric (60 degrees/s) and isometric (90 degrees) force-generating capacity were monitored for 9 days after each bout, and biopsies were taken 1 and 48 h and 4 and 7 days after bout 1 and 1 and 48 h after bout 2. The content of HSP27, alphaB-crystallin, HSP70, and desmin in the cytosolic and cytoskeleton/myofibrillar fractions of homogenized muscle samples was determined by immunoassays, and the cellular and subcellular localization of the HSPs in the myofibrillar structure was analyzed by conventional and confocal immunofluorescence microscopy and quantitative electron microscopy. The force-generating capacity was reduced by approximately 50% and did not recover completely during the 3 wk following bout 1. After bout 2, the subjects recovered within 4 days. The HSP levels increased in the cytosolic fraction after bout 1, especially HSP70 (approximately 300% 2-7 days after exercise). Increased levels of HSP27, alphaB-crystallin, and HSP70 were found in the cytoskeletal/myofibrillar fraction after both bouts, despite reduced damage after bout 2. At the ultrastructural level, HSP27 and alphaB-crystallin accumulated in Z-disks, in intermediate desmin-like structures (alphaB-crystallin), and in areas of myofibrillar disruption. In conclusion, HSP27 and alphaB-crystallin accumulated in myofibrillar structures, especially in the Z-disks and the intermediate structures (desmin). The function of the small HSPs is possibly to stabilize and protect the myofibrillar structures during and after unaccustomed eccentric exercise. The large amount of HSP27, alphaB-crystallin, and HSP70 in the cytoskeletal/myofibrillar fraction after a repeated bout of exercise suggests a protective role as part of the repeated-bout effect.

Immunohistochemical changes in the expression of HSP27 in exercised human vastus lateralis muscle

AIM

The role of HSP27 in the adaptive process of skeletal muscle to exercise, especially in humans, is not well understood. The objective of this study was to investigate immunohistochemical changes in HSP27 expression in human vastus lateralis muscle following resistance and endurance exercises.

METHODS

Two different exercise protocols were used: (1) one-leg ergometer cycling (EC, n = 6) consisting of two 30-min bouts at 40% and 75% of peak oxygen uptake, respectively, and (2) leg extension resistance exercise (RE, n = 9) including 10 sets of eight repetitions at a load corresponding to 70% of one maximal repetition (1RM). Immunohistochemistry using specific monoclonal antibodies was used to determine the location of HSP27 protein in muscle biopsies from human vastus lateralis.

RESULTS

Our results show that RE, but not EC, induced a significant appearance of scattered accumulations of HSP27 protein in muscle fibres from five of nine subjects. The number of fibres with accumulation of HSP27 in RE ranged from 0% to 32% with a mean of 6.3% of the total number of fibres.

CONCLUSION

We conclude that this rapid HSP27 protein relocation after RE is an important player in the cellular remodelling of human muscle fibres in response to exercise involving high-force contractions, but not in response to endurance exercises.

Neuromuscular fatigue and recovery in elite female handball players

The purpose of this study was to investigate the degree of neuromuscular fatigue and recovery from fatigue, following handball training and handball matches at elite level. The focus was specifically on changes in physical performance when playing three matches over the course of 3 days, which simulates a sequence in international championships. Female players from the Norwegian national handball team were tested during a 5-day training camp (seven players) and a 3-day international tournament (eight players). Testing was done before and after training sessions and matches. Neuromuscular fatigue was measured as changes in voluntary isokinetic knee extensions, jump height in counter-movement jumps, and 20 m sprint time. The results showed a significant reduction by 2-6% in all three performance tests during the training camp and by 4-7% during the tournament (sprint and jump test) (P<0.05). Slow recovery was indicated by incomplete restoration of performance between matches and training sessions. The paper discusses the insufficient recovery measured related to handball performance. Because of changes in the rules of the game and strategic tendencies towards higher speed in play, the physical demands in elite handball seems to be increasing. The results of the study indicate that coaches should consider physical loading and recovery time available when distributing playing time between individual players in international tournaments.

Recovery of skeletal muscle contractility and hormonal responses to strength exercise after two weeks of high-volume strength training

Exercise induced neuromuscular fatigue, recovery and hormonal responses were studied before (R1) and after (R2) 2 weeks of heavy strength training. Seventeen weight-trained male students were recruited into a heavy training group (HT, n = 10) and a control group (n = 7). During heavy training HT exercised leg extensors every day while control group exercised twice a week. Test workouts (R1 and R2) were used to induce neuromuscular fatigue and hormonal responses. Acute fatigue after the test workouts was reduced after heavy training in the HT group (P < 0.05) but not in the control group. Twenty-two hrs after the test workouts recovery from fatigue was not complete before heavy training, but recovery was complete after heavy training in both groups. The relative change in exercise induced cortisol and GH response, from before to after heavy training, was significantly different between groups, but for both hormones alterations in the control groups response was responsible for the between groups difference. IGF-1 concentration was reduced 22 h after the test workout performed after heavy training in the HT group (P < 0.05). In conclusion, two weeks of high volume strength training attenuated neuromuscular fatigue after a test workout with only minor changes in exercised induced hormone response.

Changes in human skeletal muscle contractility and hormone status during 2 weeks of heavy strength training

To examine neuromuscular and hormone changes during 2 weeks of heavy strength training, 18 weight-trained male students were recruited either into a heavy training group (HT, n = 11) or into a control group (Ctr, n = 7). The heavy training protocol consisted of leg-extensor workouts performed daily, while workouts were performed twice a week in the Ctr group. A test of one repetition maximum (1 RM) was performed before heavy training and on the 2nd day after heavy training. Isokinetic knee extensions, electrical stimulation, and squat jumps were performed before, on the 8th day of heavy training, and on the 4th day after heavy training. Morning blood samples (0800 hours) were drawn before, on the 8th day of heavy training, and on the 4th day after heavy training. Before, and on the 5th day after heavy training, 24 h urine samples were collected. The 1 RM leg press increased by 6 (SEM 2)% in the HT group. Testosterone and insulin-like growth factor-1 concentrations were respectively 12 (SEM 5)% and 11 (SEM 3)% lower than baseline on the 8th day of heavy training; however, hormone levels were back to baseline on the 4th day after heavy training. A significant correlation between individual changes in 1 RM leg press and changes in testosterone concentrations was observed in the HT group (r = 0.69). In the HT group, 24 h urinary catecholamine excretion increased by 26 (SEM 12)%, 3-methylhistidine excretion increased by 21 (SEM 6)% and creatinine excretion increased by 11 (SEM 5)%. There were no significant changes in the Ctr group. This work addresses the role of changes in basal hormone status (morning samples) for skeletal muscle adaptation to heavy strength training.

Recovery of skeletal muscle contractility after high- and moderate-intensity strength exercise

To examine neuromuscular fatigue and recovery, ten male strength athletes [mean (SE) 27.5 (1.4) years] performed a moderate- and a high-intensity strength exercise protocol. In the high-intensity protocol, the load was 100% of the subject's three-repetition maximum (3-RM) for squats and front squats, and 100% of the subject's 6-RM for knee extensions. In the moderate-intensity protocol, the load was 70% of the high-intensity protocol, and both protocols lasted 90 min. The contractile properties of the leg extensor muscles were tested using isokinetic knee extensions, electrical stimulation, and squat jumps. Tests were done before exercise, 5-20 min after exercise, and frequently for 33 h after exercise. The decrements in knee extension performance were greater after the high-intensity protocol (12-14%), as compared to the moderate-intensity protocol (6-7%, P < 0.01). Similar decrements were seen in squat-jumping performance after the high-intensity protocol. Decrements in electrically evoked force were also greatest after the high-intensity protocol (P < 0.05), and were more pronounced at 20 Hz stimulation than at 50 Hz stimulation (P < 0.05). The recovery of performance showed a biphasic pattern, with a rapid recovery within the first 11 h after exercise, followed by a leveling off or a second drop in performance 11-22 h after exercise. All variables were back to baseline by 3 h after the moderate-intensity protocol, while all variables were back to baseline by 33 h after the 100% protocol. The role of structural changes (excitation-contraction coupling and contractile proteins) in the long-lasting performance decrements seen after the high-intensity protocol is discussed.

Hormonal responses to high- and moderate-intensity strength exercise

The hormonal responses of nine male, strength athletes to strength exercise were examined. The athletes performed one moderate- and one high-intensity strength exercise workout. In the high-intensity workout, the load was 100% of each subject's three-repetition maximum (3-RM) for squats and front squats, and 100% of each subject's six-repetition maximum (6-RM) for leg extensions. In the moderate-intensity workout, the load was 70% of the high-intensity protocol. Rest periods between sets were 4-6 min for both workouts. Blood samples were taken before, 30 min into, and every 15 min for the 1st h after exercise, and then 3, 7, 11, 22 and 33 h after exercise, thus allowing examination of both the acute and prolonged hormonal responses. Blood samples were analyzed for testosterone, luteinizing hormone (LH), follicle stimulating hormone (FSH), cortisol, adrenocorticotrophic hormone (ACTH), growth hormone (GH), insulin-like growth factor (IGF-1), insulin, sex hormone binding globulin, creatine kinase, total protein, glucose and lactate. The acute responses of testosterone and cortisol were greater during the high-intensity protocol as compared to the moderate-intensity protocol. The cortisol response was associated with an increase in ACTH concentration. LH and FSH showed no response to either protocol. Acute GH responses were not different between protocols. There were great inter-individual differences in acute GH responses to both protocols. There were no significant differences between protocols with regard to prolonged responses for any hormone. In both trials, IGF-1 concentrations were significantly lower at 0800 hours the morning after exercise as compared to concentrations found at 0800 hours the morning before exercise. The mechanisms responsible for reducing IGF-1 concentration in these trials are unclear, and it is not known if this reduction observed 22 hours after exercise is of physiological significance.

Omega-3 fatty acid supplementation does not improve maximal aerobic power, anaerobic threshold and running performance in well-trained soccer players

In a randomized, placebo-controlled study the effect of 10 weeks of supplementation with either 5.2 g of a concentrated fish oil triglyceride (Triomar) enriched in omega-3 fatty acids (1.60 g/day EPA and 1.04 g/ day DHA) or 5.2 g corn oil (serving as placebo) on maximal aerobic power, anaerobic threshold and running performance was assessed in 28 well-trained male soccer players (18-35 years). Supplements were given as 650-mg capsules. Capsule assignment was randomized to one omega-3 group (n = 15), given eight Triomar capsules per day, and one placebo group (n = 13), given eight capsules of corn oil per day. During the 10-week supplementation period the subjects maintained their usual diets and training regimes. Red blood cell (RBC) osmotic fragility, triglycerides and fatty acid composition in plasma were assessed before and after the supplementation period. The pre- and post-supplementation tests of maximal aerobic power, anaerobic power and running performance showed no significant difference between the two groups. Subjects in the omega-3 group had significantly reduced plasma triglycerides, rose EPA (175%) and DHA (40%) in the total lipid fraction of plasma after supplementation. RBC osmotic fragility did not change. In conclusion, the results do not support the hypothesis that endurance athletes can improve maximal aerobic performance by omega 3-fatty acid supplementation.