骨骼肌不同速度离心收缩时肌力与sEMG交互特征     

刘耀荣 《西安体育学院学报》2008,25(5)

目的探讨骨骼肌在不同速度离心收缩过程中力矩、功率输出及神经支配活动特性。方法12名男性受试着,在ISOMED2000等速测力系统上分别以60°/s和180°/s的角速度完成离心收缩,用ME6000无线肌电遥测系统同步测试受试者股外侧肌、股二头肌肌电信号。结果屈伸肌群在60°/sec、180°/sec离心用力时力矩、功、功率均随速度增大而增加(P<0.01)。sEMG显示,股外侧肌和股二头肌都被相应的动员,伸肌肌电各参数普遍高于屈肌。iEMG随速度增加而下降,RMS、MF和MPF都随运动速度增加而增加。结论在自主性离心收缩过程中,随着收缩速度的加快,力矩、做功增加,但肌电活性(iEMG)降低,与向心收缩不同,离心收缩有着独特的力量输出和神经支配方式。  相似文献   

一次大负荷离心运动对大鼠骨骼肌线粒体分布及SDHA和CytC蛋白表达的影响     

于滢  王瑞元  于亮  张欣  李俊平 《北京体育大学学报》2016,39(11):51-56

摘要：目的：观察一次大负荷运动后线粒体的分布以及线粒体SDHA和CytC蛋白的表达变化。方法：42只SD大鼠经适应后随机分为安静组（6只）和一次大负荷离心运动组（36只）。运动组在跑台上进行90 min速度为16 m/min的离心运动,坡度-16°。运动后分别在0、6、12、24、48、72 h取材。透射电镜观察大鼠骨骼肌线粒体分布,western blotting测定骨骼肌线粒体SDHA和CytC蛋白的表达。结果：一次大负荷离心运动后,骨骼肌肌膜下线粒体面积和数量均升高,肌原纤维间线粒体面积和数量呈现减少趋势;与安静组相比,肌膜下线粒体面积增加明显;骨骼肌线粒体SDHA蛋白表达呈现先降低后升高的趋势,而CytC蛋白呈现升高趋势。结论：一次大负荷离心运动后骨骼肌线粒体分布出现肌膜下聚集现象,且线粒体SDHA蛋白表达在运动后下调明显,可能是导致线粒体功能下降的原因之一。  相似文献   

Acute adaptations and subsequent preservation of strength and speed measures following a Nordic hamstring curl intervention: a randomised controlled trial     

James Siddle  Matt Greig  Kristian Weaver  Richard Michael Page  Damian Harper 《Journal of sports sciences》2019,37(8):911-920

This randomised controlled trial investigated changes in eccentric hamstring strength, 10m sprint speed, and change-of-direction (COD) performance immediately post Nordic hamstring curl (NHC) intervention and following a 3-week detraining period.

Fourteen male team sports athletes were randomised to a do-as-usual control group (CG; n = 7) or to a NHC intervention group (NHC; n = 7). Isokinetic dynamometry at 180°/s evaluated eccentric hamstring strength immediately post-intervention as the primary outcome measure. Secondary outcomes included 10 m sprint time and COD. Each outcome was measured, pre, immediately post-intervention and following a 3-week detraining period.

Immediately post-intervention significant group differences were observed in the NHC group for eccentric hamstring strength (31.81 Nm^?1 vs. 6.44 Nm^?1, P = 0.001), COD (?0.12 s vs. 0.20 s; P = 0.003) and sprint (- 0.06 s vs. 0.05 s; P = 0.024) performance. Performance improvements were maintained following a detraining period for COD (?0.11 s vs. 0.20 s; P = 0.014) and sprint (?0.05 s vs. 0.03 s, P = 0.031) but not eccentric hamstring strength (15.67 Nm^?1 vs. 6.44 Nm^?1, P = 0.145) These findings have important implications for training programmes designed to reduce hamstring injury incidence, whilst enhancing physical qualities critical to sport.  相似文献   

飞轮等惯性训练对改善肌肉萎缩、预防运动损伤和康复治疗的研究进展     

苏玉莹 《中国体育科技》2021,(4):50-55

飞轮等惯性训练(以下简称"飞轮训练")因其特殊的离心运动和抗阻运动性能而受到教练员和科研人员的重视。通过飞轮训练对运动员和大众人群的损伤和康复等相关研究进行综述,理清了飞轮训练的起源与发展,分析影响其背后的生理机制,进一步探究改善肌肉萎缩、预防损伤和神经康复等方面的研究进展。研究发现,飞轮训练最早用于预防航天员太空失重环境下的肌肉萎缩问题,后来被逐渐运用到竞技体育和康复领域。影响飞轮训练的生理机制包括肌肉过度牵拉产生的牵张反射、神经系统动员的效果和肌腱复合体的效果。飞轮训练在改善肌肉萎缩和老年人生活表现方面具有显著效果,并且在预防运动损伤、提高损伤后的康复和中枢神经系统的适应性方面具有优越性。  相似文献   

Downhill walking to improve lower limb strength in healthy young adults     

《European Journal of Sport Science》2013,13(8):806-812

Abstract

Walking is the most natural physical activity to maintain and improve fitness and health. Walking downhill is usefully adopted to plan training programmes to improve the strength, particularly in older adults. The present research was aimed to evaluate the influence of downhill walking on leg strength in young adult. A total of 32 females (age 26 ± 4 years; height 1.64 ± 0.05 m; body mass 57.6 ± 5.6 kg) were divided into four groups and they carried out an exercise intervention consisting of three sessions per week for 6 weeks, each lasting 30 minutes. Groups were defined at several workloads characterised by treadmill inclination (%) and walking speed (m·s^?1): Level Walking at treadmill inclination 0% and walking speed 1.0; Uphill Walking at +20%, 0.75; Downhill Walking (DW) at ?20%, 1.36; and Mixed Walking at +20%, 0.75 and ?20%, 1.36 each lasting 15 minutes. Maximum voluntary contraction (MVC) developed by the Quadriceps Femoris and Endurance Time at 60% MVC were evaluated before and after experimental period. At the end of each session, Borg's scale and Visual Analogue Scale (VAS) were adopted in order to evaluate perception of rate exertion and pain. Statistical analysis showed significant only in MVC for DW in both right and left legs. Borg's scale and VAS described light activity free of pain. Present findings showed how an eccentric exercise, short lasting and at a low workload, can be useful in inducing improvements in leg strength.  相似文献   

The effects of protease supplementation on skeletal muscle function and DOMS following downhill running     

Paul C Miller  Stephen P Bailey  Megan E Barnes  S Janelle Derr  Eric E Hall 《Journal of sports sciences》2013,31(4):365-372

Protease supplementation has been shown to attenuate soft tissue injury resulting from intense exercise. The aim of this study was to evaluate the effects of protease supplementation on muscle soreness and contractile performance after downhill running. Ten matched pairs of male participants ran at a ?10% grade for 30?min at 80% of their predicted maximal heart rate. The participants consumed two protease tablets (325?mg pancreatic enzymes, 75?mg trypsin, 50?mg papain, 50?mg bromelain, 10?mg amylase, 10?mg lipase, 10?mg lysozyme, 2?mg chymotrypisn) or a placebo four times a day beginning 1 day before exercise and lasting a total of 4 days. The participants were evaluated for perceived muscle soreness of the front and back of the dominant leg, pressure pain threshold by dolorimetry of the anterior medial, anterior lateral, posterior medial and posterior lateral quadrants of the thigh, and knee extension/flexion torque and power. The experimental group demonstrated superior recovery of contractile function and diminished effects of delayed-onset muscle soreness after downhill running when compared with the placebo group. Our results indicate that protease supplementation may attenuate muscle soreness after downhill running. Protease supplementation may also facilitate muscle healing and allow for faster restoration of contractile function after intense exercise.  相似文献   

Changes in the relationship between joint angle and torque production associated with the repeated bout effect     

Malachy P McHugh  Danielle T Tetro 《Journal of sports sciences》2013,31(11):927-932

A single bout of eccentric exercise induces a protective adaptation against damage from a repeated bout. The aim of this study was to determine whether this repeated bout effect is due to a change in the length–tension relationship. Twelve individuals performed an initial bout of six sets of 10 eccentric quadriceps contractions and then performed a repeated bout 2 weeks later. Eccentric contractions were performed on an isokinetic dynamometer at 1.04 rad?·?s^?1 with a target intensity of 90% of isometric strength at 70° of knee flexion. Isometric strength and pain were recorded before and after both eccentric bouts and on each of the next 3 days. Isometric strength was tested at 30°, 50°, 70°, 90° and 110° of knee flexion. On the days following the initial bout, there was a significant loss of isometric strength at all knee flexion angles except 110° (bout×angle: P?<0.01). On day 2, strength averaged 86% of baseline for 30–90° and 102% of baseline for 110°. Strength loss and pain after the initial bout was contrasted by minimal changes after the repeated bout (pain: P?<0.001; strength: P?<0.01). The repeated bout effect was associated with a rightward shift in the length–tension curve; before the repeated bout, isometric strength was 6.8% lower at 30° and 13.6% higher at 110° compared with values before the initial bout (bout×angle: P?<0.05). Assuming that torque production at 110° occurs on the descending limb of the length–tension curve, the increase in torque at 110° may be explained by a longitudinal addition of sarcomeres. The addition of sarcomeres would limit sarcomere strain for subsequent eccentric contractions and may explain the repeated bout effect observed here.  相似文献   

Functional hamstrings: quadriceps ratios in elite women's soccer players     

Nathaniel D.M. Jenkins  Matthew J. Hawkey  Pablo B. Costa  Ryan E. Fiddler  Brennan J. Thompson  Eric D. Ryan 《Journal of sports sciences》2013,31(6):612-617

Abstract

We compared starters and non-starters for various isokinetic strength variables in elite women’s soccer players. A convenience sample of 10 starters (mean ± s; age = 20 ± 2 years; height = 170 ± 4 cm; body mass = 65 ± 5 kg) and 7 non-starters (age = 20 ± 1 years; height = 164 ± 3 cm; body mass = 63 ± 4 kg) performed maximal voluntary muscle actions of the leg extensors (concentric) and flexors (eccentric) on an isokinetic dynamometer in order to measure concentric peak torque for the leg extensors, eccentric peak torque for the leg flexors, and the functional hamstrings:quadriceps (H:Q) ratio at 1.047 rad · s^-1 and 4.189 rad · s^-1 concentric peak torque for the leg extensors was not different between starters and non-starters. However, it was greater at 1.047 rad · s^-1 than at 4.189 rad · s^-1 in both groups. Eccentric peak torque for the leg flexors was greater for the starters versus non-starters at 4.189 rad · s^-1. Eccentric strength of the leg flexors at fast movement velocities may be used as an effective physiological profile and may discriminate between playing status in elite women’s soccer players.  相似文献   

Relationships of hip abductor strength,neuromuscular control,and hip width to femoral length ratio with peak hip adduction angle in healthy female runners     

Richard A. Brindle  D. David Ebaugh  John D. Willson  Margaret A. Finley  Patricia A. Shewokis  Clare E. Milner 《Journal of sports sciences》2020,38(20):2291-2297

ABSTRACT

A large peak hip adduction angle during running is a risk factor for several overuse injuries in women. The purpose of this study was to determine if female runners with a large peak hip adduction angle have differences in eccentric hip abductor muscle strength, hip neuromuscular control, and/or hip width to femoral length ratio (HW:FL) compared to those with a small angle. Hip adduction during running, hip strength, hip control, and HW:FL were measured in sixty healthy female runners (1.66 ± 0.06 m; 63.2 ± 8.3 kg; 27 ± 6 years). Data from twenty runners with the largest and twenty with the smallest peak hip adduction angles were analysed. Between-group differences in hip strength, control, and HW:FL were determined using independent t-tests (p < 0.05). Variables that were significantly different between groups were entered into a regression model. Runners in both groups had similar hip strength (p = 0.90) and control (p = 0.65). HW:FL was greater in the large peak angle group (p = 0.04), but only explained a small amount of peak hip adduction angle variance for all sixty runners (R² = 0.05). Alarge peak hip adduction angle in some healthy female runners may simply be instinctive as there were no deficiencies in the strength or neuromuscular control constructs assessed.  相似文献   

PI3K/Akt/GSK-3β在去负荷及再负荷大鼠腓肠肌蛋白代谢中的作用   总被引：1，自引：0，他引：1  

张飞鹏  吴金富  王晶 《北京体育大学学报》2011,(9):48-50,61

目的:观察去负荷及再负荷过程PI3K/Akt/GSK-3β信号途径的变化,并探讨该过程对骨骼肌蛋白分解及合成代谢的影响。研究方法:24只雌性SD大鼠随机分对照组(NC)、去负荷14 d模型组(TS)、去负荷14 d+再负荷自由活动14 d组(NR)、去负荷14 d+再负荷离心运动14 d组(ER)。用免疫印迹半定量分析PI3K、Akt、GSK-3β和P-GSK-3β的表达。研究结果:与NC组相比,TS组腓肠肌总蛋白含量显著下降(P<0.05);以不同方式再负荷14 d都能使腓肠肌蛋白含量提高,NR与ER组之间没有显著差异;ER组PI3K蛋白表达显著高于NR组(P<0.05);ER组Akt也高于NR组,但没有显著性差异。ER组的P-GSK-3β和GSK-3β蛋白表达与NR组的相似趋势,其中ER组的P-GSK-3β与NC组相比,有显著性差异(P<0.05);而GSK3β则显著增加(P<0.05)。结论:在去负荷条件下,PI3K/Akt/GSK-3β信号对骨骼肌蛋白分解影响较小;再负荷条件下,离心运动能加强PI3K/Akt/GSK-3β信号作用,参与骨骼肌蛋白合成。  相似文献