Response of males and females to high-force eccentric exercise     

John Rinard  Priscilla M. Clarkson  Lucille L. Smith  Marlene Grossman 《Journal of sports sciences》2013,31(4):229-236

It has previously been shown that females incur less muscle damage than males after strenuous exercise, but limited data are available for humans. To determine possible differences between the sexes in humans, the response to high-force eccentric exercise was examined in a large sample of women (n = 83) and men (n = 82). The participants performed a bout of eccentric exercise of the elbow flexors consisting of 70 maximal repetitions. Isometric strength, resting elbow angle and muscle soreness were measured before, immediately after (except soreness) and then daily for 7 days after exercise. There was a significant loss in strength among both groups (69% for women and 63% for men) (P?0.01) immediately after exercise; at 168 h post-exercise, women still had a 27% strength loss and men had a 24% strength loss. No significant difference in strength loss or recovery rate was found between men and women. Soreness reached peak values 32-48 h post-exercise (P?0.01), with no significant difference between men and women. Range of motion decreased significantly until 3 days after exercise (14.6° or 0.255 rad loss for women; 12.2° or 0.213 rad loss for men) (P?0.01); at 168 h post-exercise, the women and men still showed a loss of 4.8° (0.084 rad) and 4.0° (0.07 rad), respectively. There was a significant interaction of sex x time (P?0.01); a post-hoc test indicated that the women experienced a greater loss in range of motion at 72 h than men and this difference was maintained to 168 h post-exercise (P?0.01). Thus, our results do not support the contention that women have a lower response to eccentric exercise than men.  相似文献   

Anthropometric and physiological predispositions for elite soccer     

T. Reilly  J. Bangsbo  A. Franks 《Journal of sports sciences》2013,31(9):669-683

This review is focused on anthropometric and physiological characteristics of soccer players with a view to establishing their roles within talent detection, identification and development programmes. Top-class soccer playershave to adapt to the physical demandsof the game, which are multifactorial. Players may not need to have an extraordinary capacity within any of the areas of physical performance but must possess a reasonably high level within all areas. This explains why there are marked individual differences in anthropometric and physiological characteristics among top players. Various measurements have been used to evaluate specific aspects of the physical performance of both youth and adult soccer players.The positional role of a player is related to his or her physiological capacity. Thus, midfield players and full-backs have the highest maximal oxygen intakes (> 60 ml·kg -1 ·min -1 ) and perform best in intermittent exercise tests. On the other hand, midfield players tend to have the lowest muscle strength. Although these distinctions are evident in adult and elite youth players, their existence must be interpreted circumspectly in talent identification and development programmes. A range of relevant anthropometric and physiological factors can be considered which are subject to strong genetic influences (e.g. stature and maximal oxygen intake) or are largely environmentally determined and susceptible to training effects. Consequently, fitness profiling can generate a useful database against which talented groups may be compared. No single method allows for a representative assessment of a player's physical capabilities for soccer. Weconclude that anthropometric and physiological criteria do have a role as part of a holistic monitoring of talented young players.  相似文献   

Effect of stride length manipulation on symptoms of exercise-induced muscle damage and the repeated bout effect     

Ann V. Rowlands  Roger G. Eston  Caroline Tilzey 《Journal of sports sciences》2013,31(5):333-340

This study assessed the effects of stride length on symptoms of exercise-induced muscle damage after downhill running and whether the extent of the symptoms sustained in a repeated bout of downhill running are influenced by stride length manipulation in the first bout. Eighteen males aged 21.1 - 0.6 years (mean - s) were allocated to one of three groups for bout one: preferred stride frequency, overstride and understride. Bout two was performed 2 weeks later at the participants' preferred stride frequency. Maximal isometric force and perceived muscle soreness were assessed pre-test and 30 min, 24, 48 and 72 h post-exercise for each downhill run. Threefactor analyses of variance with repeated measures on time and bout were used for analysis. Results revealed a three-way interaction for soreness (F 8,60 = 3.56, P ? 0.05) and relative isometric strength (F 5.0,37.8 = 3.2, P ? 0.05). Post-hoc analyses revealed that, after bout one, the overstride group perceived most soreness and the understride group retained most strength. After the second bout, the overstride and preferred stride frequency groups perceived less soreness than the preferred stride frequency group in bout one. Strength retention was greater after bout two for all groups. In conclusion, strength retention after a repeated bout appears to be independent of the damage experienced in the initial bout of downhill running. However, understriding may provide least protection against soreness in a subsequent bout.  相似文献   

The effect of induced alkalosis and submaximal cycling on neuromuscular response during sustained isometric contraction     

Angus M. Hunter  Giuseppe De Vito  Claire Bolger  Hugh Mullany  Stuart D. R. Galloway 《Journal of sports sciences》2013,31(12):1261-1269

Abstract

The aim of this study was to determine if inducing metabolic alkalosis would alter neuromuscular control after 50 min of standardized submaximal cycling. Eight trained male cyclists (mean age 32 years, s = 7; [Vdot]O_2max 62 ml · kg^?1 · min^?1, s = 8) ingested capsules containing either CaCO₃ (placebo) or NaHCO₃ (0.3 g · kg^?1 body mass) in eight doses over 2 h on two separate occasions, commencing 3 h before exercise. Participants performed three maximal isometric voluntary contractions (MVC) of the knee extensors while determining the central activation ratio by superimposing electrical stimulation both pre-ingestion and post-exercise, followed by a 50-s sustained maximal contraction in which force, EMG amplitude, and muscle fibre conduction velocity were assessed. Plasma pH, blood base excess, and plasma HCO₃ were higher (P < 0.01) during the NaHCO₃ trial. After cycling, muscle fibre conduction velocity was higher (P < 0.05) during the 50-s sustained maximal contraction with NaHCO₃ than with placebo (5.1 m · s^?1, s = 0.4 vs. 4.2 m · s^?1, s = 0.4) while the EMG amplitude remained the same. Force decline rate was less (P < 0.05) during alkalosis-sustained maximal contraction and no differences were shown in central activation ratio. These data indicate that induced metabolic alkalosis can increase muscle fibre conduction velocity following prolonged submaximal cycling.  相似文献   

Indirect evidence of human skeletal muscle damage and collagen breakdown after eccentric muscle actions     

S. BROWN  S. DAY  A. DONNELLY 《Journal of sports sciences》2013,31(5):397-402

Indirect markers of muscle damage and collagen breakdown were recorded for up to 9 days after a bout of concentric, followed by a bout of eccentric, muscle actions. Nine untrained participants performed two bouts of 50 maximum effort repetitions on an isokinetic dynamometer (angular velocity 1.05 rad.s-1, range of motion 1.75 rad). An initial concentric bout of muscle actions was followed by an eccentric bout 21 days later, using the same knee extensors. Concentric actions induced no changes in maximum voluntary isometric contraction force (MVC),nor induced any changes in the serum enzyme activities of creatine kinase, a lactate dehydrogenase isoenzyme (LDH-1), or alkaline phosphatase. Similarly, concentric actions induced no change in markers of collagen breakdown,namely plasma hydroxyproline and serum type 1 collagen concentration.In contrast,eccentric actions induced a 23.5 ± 19.0% (mean ± s) decrease in MVC immediately post-exercise (P< 0.05), and increased the serum enzyme activities of creatine kinase and LDH-1 to 486 ± 792 and 90 ± 11 IU.l-1 respectively on day 3 post-exercise, and to 189 ± 159 and 96 ±13 IU.l-1 respectively on day 7 post-exercise (all P < 0.05). Eccentric actions induced no significant changes in plasma hydroxyproline, but increased collagen concentration on days 1 and 9 post-exercise (48.6% and 44.3% increases above pre-exercise on days 1 and 9 respectively; both P < 0.05). We conclude that eccentric but not concentric actions may result in temporary muscle damage, and that collagen breakdown may also be affected by eccentric actions. With caution, indices of collagen breakdown may be used to identify exercise-induced damage to connective tissue.  相似文献   

Muscle capacity and physical function in older women: What are the impacts of resistance training?     

《运动与健康科学(英文)》2014,3(3):179-188

The number of older adults (individuals ≥65 years), particularly women, in our society is increasing and understanding the impact of exercise on muscle capacity (e.g., strength and power) and subsequently physical function is of utmost importance to prevent disability and maintain independence. Muscle capacity declines with age and this change negatively impacts physical function in older women. Exercise, specifically resistance training, is recommended to counteract these declines; however, the synergistic relationships between exercise, muscle capacity, and physical function are poorly understood. This review will summarize the literature regarding age-related changes in the aforementioned variables and review the research on the impact of resistance training interventions on muscle capacity and physical function in older women. Recommendations for future research in this area will be discussed.  相似文献   

耐力运动与高脂饮食对Wistar大鼠骨骼肌线粒体融合分裂蛋白表达的影响研究     

郑义  徐晓阳  薄海  张勇 《广州体育学院学报》2021,(1)

目的:观察耐力运动与高脂饮食干预对肥胖大鼠骨骼肌线粒体融合与分裂蛋白表达的影响。方法:48只Wistar大鼠分N组(16只)与H组(32只)普食/高脂饲喂造模8周,随后分为NNC组、NNE组、HHC组、HHE组、HNC组与HNE组,NNC组、NNE组、HNC组与HNE组使用普食饲喂9周,HHC组与HHE组继续使用高脂饲喂9周,NNE组、HHE组与HNE组进行9周耐力运动干预。结果:高脂饲喂后大鼠骨骼肌线粒体融合蛋白MFN1、MFN2表达减少,分裂蛋白FIS1表达增加,耐力运动干预增加了高脂饲喂后大鼠骨骼肌线粒体MFN1、MFN2的表达,降低了DRP1、FIS1的表达。结论:高脂饲喂显著降低了骨骼肌线粒体融合蛋白的表达,增加了分裂蛋白的表达,耐力运动干预显著增加了骨骼肌线粒体融合蛋白的表达,显著降低了HFD干预后骨骼肌线粒体分裂蛋白的表达。  相似文献   

发展肌肉爆发力的“最大动量训练法”研究   总被引：7，自引：0，他引：7  

刘北湘  石玉琴 《成都体育学院学报》1994,20(1):78-85

本文是一项实验性研究报告，目的是验证作者提出的“最大动量训练法”设想。作者采用瑞士产Ｋｉｓｔｌｅｒ测力系统，测定了１７名受试者腿部力量训练的动作。根据所获动力学数据确定了受试者所应采用的适宜载荷量；然后对１７名受试者进行了三个月的力量训练。前后的实验材料分析对比得出结论：１．载荷量变化时，人体完成动作时的肌肉输出冲量不同，且存在极值。２．用输出冲量极值点所对应的载荷量来训练肌肉力量，能更有效的发展肌肉的爆发性力量。３．用动力学指标来确定载荷量的方法，较合理的考虑了人体自重、不同练习动作差异、肌肉成分差异和完成动作速度等问题。使力量训练更具有针对性、准确性和实效性。  相似文献   

Application of the neuromuscular fatigue threshold treadmill test to muscles of the quadriceps and hamstrings     

Clayton L. Camic  Attila J. Kovacs  Trisha A. VanDusseldorp  Ethan C. Hill  Evan A. Enquist 《运动与健康科学(英文)》2020,9(6):628-633

PurposeThe purposes of the present study were: (1) to determine whether the physical working capacity at the fatigue threshold (PWC_FT) model that has been used for estimating the onset of neuromuscular fatigue in the vastus lateralis (VL) during incremental treadmill running could also be applied to the vastus medialis (VM), biceps femoris (BF), and semitendinosus (ST) muscles; and (2) if applicable, to compare the running velocities associated with the PWC_FT among these muscles.MethodsEleven subjects (age 21.7 ± 1.8 years) performed an incremental treadmill test to exhaustion with electromyographic signals recorded from the VL, VM, BF, and ST.ResultsThe results indicated there were no significant (p > 0.05) mean differences in the running velocities associated with the PWC_FT for the VL (14.4 ± 2.0 km/h), VM (14.3 ± 1.9 km/h), BF (13.8 ± 1.8 km/h), and ST (14.7 ± 2.3 km/h). In addition, there were significant inter-correlations (r = 0.68–0.88) among running velocities associated with the PWC_FT of each muscle. Individual results also indicated that 9 of the 11 subjects exhibited identical PWC_FT values for at least 3 of the 4 muscles, but there were no uniform patterns for any intra-individual differences.ConclusionThe findings of the present study suggested that the PWC_FT test is a viable method to identify neuromuscular fatigue in the quadriceps and hamstrings during incremental treadmill exercise and results in consistent PWC_FT values among these muscles.  相似文献   

Effects of compression garments on surface EMG and physiological responses during and after distance running     

Wei-Chun Hsu  Li-Wen Tseng  Fu-Chun Chen  Li-Chu Wang  Wen-Wen Yang  Yi-Jia Lin  Chiang Liu 《运动与健康科学(英文)》2020,9(6):685-691

BackgroundThe few previous studies that focused on the effects of compression garments (CG) on distance running performance have simultaneously measured electromyogram, physiological, and perceptual parameters. Therefore, this study investigated the effects of CG on muscle activation and median frequency during and after distance running, as well as blood-lactate concentration and rating of perceived exertion (RPE) during distance running.MethodsEight healthy male recreational runners were recruited to randomly perform two 40 min treadmill running trials, one with CG, and the other with control garment made of normal cloth. The RPE and the surface electromyography (EMG) of 5 lower extremity muscles including gluteus maximus (GM), rectus femoris (RF), semitendinosus (ST), tibialis anterior (TA), and gastrocnemius (GAS) were measured during the running trial. The blood-lactate levels before and after the running trial were measured.ResultsWearing CG led to significant lower muscle activation (p < 0.05) in the GM (decreased 7.40%–14.31%), RF (decreased 4.39%–4.76%), and ST (decreased 3.42%–7.20%) muscles; moreover, significant higher median frequency (p < 0.05) in the GM (increased 5.57%) and ST (increased 10.58%) muscles. Wearing CG did not alter the RPE values or the blood-lactate levels (p > 0.05).ConclusionWearing CG was associated with significantly lower muscle activation and higher median frequency in the running-related key muscles during distance running. This finding suggested that wearing CG may improve muscle function, which might enhance running performance and prevent muscle fatigue.  相似文献