不同形式肌肉收缩时肌电参数变化特征及机制   总被引：1，自引：1，他引：0       下载免费PDF全文

张立  王仁纲 《武汉体育学院学报》2008,42(12):49

研究目的：探讨动力性与静力性肌肉收缩时EMG各参数的变化特征及疲劳时各指标的差异,比较不同项目运动员肌肉收缩特征对EMG参数的影响及与该项目的关系。研究方法：27名受试者分为两组,第一组为赛艇运动员（组一）,第二组为田径爆发性力量项目（跳跃、短跑）专选运动员（组二）。受试者以2／3Mvc做静力性持续等长收缩,动力性持续肌肉收缩则采用本人的MVC,同时记录EMG信号,分析IEMG、E／T值和MF。研究结果：持续静力性肌肉收缩时,随疲劳的发展赛艇运动员与田径运动员IEMG、E／T值均显著升高。但赛艇运动员从运动开始至80％时段一直保持平稳,此后迅速上升。静力性收缩时两组运动员随疲劳发展MF从高频向低频转移,但田径运动员频率下降速率要快于赛艇运动员。结论：赛艇运动训练促使大脑皮层动员运动单位工作更具有时间耐久性。快速、爆发式运动使疲劳时大脑皮层兴奋性下降更快,肌肉更易于疲劳。  相似文献   

Sarcopenia的健康维护成本及应对策略   总被引：1，自引：0，他引：1  

李海鹏  丁树哲  卢健  陈彩珍 《西安体育学院学报》2008,25(6)

Sarcopenia已成为当今多数国家面临的主要公共健康问题之一。在重视生活质量、崇尚健康的现代社会,为了维护众多增龄性疾病人们花费了大量的医疗成本,随着我国乃至世界人口老龄化时代的到来,患Sarcopenia的老年人口将会急剧增加,降低其健康成本并制定应对策略成为迫在眉睫的社会问题。  相似文献   

脏腑运动训练在现代生活方式中的新发展     

彭莉 《湖北体育科技》2008,27(3):264-266

脏腑内的平滑肌可以通过自主运动诱导和激发反射运动,使其肌肉耐力、肌肉力量和柔韧度达到最佳的状态,并迅速有效促进人体的内分泌的增加,从而达到调节内脏功能,调整内分泌系统,缓解和治疗内分泌系统紊乱等亚健康状态。简便、便易的针对人体脏腑的运动方法,将为现代人树立一种全新的养生概念,并提供一种有效实用的健身、养生新方式。  相似文献   

腰部竖脊肌疲劳运动过程中表面肌电信号线性和非线性指标的变化   总被引：1，自引：0，他引：1  

王翔 《浙江体育科学》2008,30(6):104-106

通过等长背伸运动负荷诱发腰部竖脊肌疲劳并记录全程表面肌电（sEMG）信号,分别以快速傅立叶变换（FFT）计算平均功率频率MPF和非线性RQA方法计算确定性线段百分数（?T）。结果显示,MPF随着肌肉疲劳的发展而逐渐下降,而?T呈现反向变化趋势,提示肌肉疲劳时的sEMG信号规律性在增强。?T的变异系数CV比MPF的小,说明?T作为腰部肌肉功能状态的评价指标具有独特的优势。  相似文献   

The dynamic control ratio at the equilibrium point (DCRe): introducing relative and absolute reliability scores     

Tobias Alt  Axel J. Knicker  Heiko K. Strüder 《Journal of sports sciences》2017,35(7):688-693

Analytical methods to assess thigh muscle balance need to provide reliable data to allow meaningful interpretation. However, reproducibility of the dynamic control ratio at the equilibrium point has not been evaluated yet. Therefore, the aim of this study was to compare relative and absolute reliability indices of its angle and moment values with conventional and functional hamstring–quadriceps ratios. Furthermore, effects of familiarisation and angular velocity on reproducibility were analysed. A number of 33 male volunteers participated in 3 identical test sessions. Peak moments (PMs) were determined unilaterally during maximum concentric and eccentric knee flexion (prone) and extension (supine position) at 0.53, 1.57 and 2.62 rad · s^–1. A repeated measure, ANOVA, confirmed systematic bias. Intra-class correlation coefficients and standard errors of measurement indicated relative and absolute reliability. Correlation coefficients were averaged over respective factors and tested for significant differences. All balance scores showed comparable low-to-moderate relative (<0.8–0.9) and good absolute reliability (<10%). Relative reproducibility of dynamic control equilibrium parameters augmented with increasing angular velocity, but not with familiarisation. At 2.62 rad · s^–1, high (moment: 0.906) to moderate (angle: 0.833) relative reliability scores with accordingly high absolute indices (4.9% and 6.4%) became apparent. Thus, the dynamic control equilibrium is an equivalent method for the reliable assessment of thigh muscle balance.  相似文献   

Effects of different warm-up modalities on power output during the high pull     

Matthew John Barnes  Ashley Petterson  Darryl J. Cochrane 《Journal of sports sciences》2017,35(10):976-981

This study compared the effects of six warm-up modalities on peak power output (PPO) during the high-pull exercise. Nine resistance-trained males completed six trials using different warm-ups: high-pull specific (HPS), cycle, whole body vibration (WBV), cycle+HPS, WBV+HPS and a control. Intramuscular temperature (T_m) was increased by 2°C using WBV or cycling. PPO, T_m and electromyography (EMG) were recorded during each trial. Two high-pulls were performed prior to and 3 min after participants completed the warm-up. The greatest increase in PPO occurred with HPS (232.8 ± 89.7 W, P < 0.001); however, this was not different to combined warm-ups (cycle+HPS 158.6 ± 121.1 W; WBV+HPS 177.3 ± 93.3 W, P = 1.00). These modalities increased PPO to a greater extent than those that did not involve HPS (all P < 0.05). HPS took the shortest time to complete, compared to the other conditions (P < 0.05). EMG did not differ from pre to post warm-up or between modalities in any of the muscles investigated. No change in T_m occurred in warm-ups that did not include cycling or WBV. These results suggest that a movement-specific warm-up improves performance more than temperature-related warm-ups. Therefore, mechanisms other than increased muscle temperature and activation may be important for improving short-term PPO.  相似文献   

Nrf2在有氧运动训练中对小鼠骨骼肌抗氧化能力的作用     

何诗依  张缨 《北京体育大学学报》2017,40(12):50-54

摘要：目的：Nrf2是机体氧化还原平衡的主要调节因子,本研究试图探讨Nrf2在有氧运动训练中对小鼠骨骼肌抗氧化能力的作用。方法：8周龄野生C57BL/6J小鼠和Nrf2敲除小鼠40只,雌雄各半。进一步各为安静组和运动组,每组10只,共4组：分别为野生安静组（WC）,野生运动组（WE）,敲除安静组（KC）和敲除运动组（KE）。运动组进行4周运动强度为70%VO2max跑速的跑台运动,每周运动6 d,每天运动1 h。运动组最后一次运动后休息48 h脱颈处死,取小鼠后腿骨骼肌。RT-PCR测量Nrf2及Nrf2介导的抗氧化基因mRNA表达量;Western blot法测定骨骼肌Nrf2及抗氧化蛋白含量; GSH试剂盒测量GSH/GSSG比值。结果：1）在安静情况下,KC组和WC组相比,骨骼肌中GSR、NQO1、GCLc、GPX、HO-1和SOD2这6个抗氧化蛋白表达以及GSH/GSSG值没有显著性改变。 2）4周有氧运动训练之后,Nrf2敲除运动组的大部分抗氧化蛋白（CAT, NQO1-1, GCLc, HO-1 and SOD2）和GSH/GSSG值都要显著低于野生运动组。结论：4周70%VO2max强度的有氧运动训练,增加了成年Nrf2敲除和野生鼠骨骼肌抗氧化蛋白表达量和GSH/GSSG比值的差异,而在无训练安静情况下在两种鼠中这些指标的差异不大。说明Nrf2对有氧运动训练中骨骼肌的抗氧化反应起着非常重要的作用。  相似文献   

大剂量补充亮氨酸对抗阻运动所致骨骼肌损伤的影响     

夏志  赵艳  孟思进  史仍飞  尚画雨  王良峡  刘娟  苏全生 《北京体育大学学报》2017,40(10):56-62

摘要：目的：探讨补充亮氨酸对无训练史被试进行抗阻运动所致骨骼肌损伤的影响。方法：16名青年男性大学生据体重随机分为补充亮氨酸组与安慰剂对照组,亮氨酸和安慰剂组被试从测试日深蹲抗阻运动前3周直至运动后4 d分别以每千克体重150 mg剂量摄入150 mL亮氨酸或糊精溶液。测试日各组被试以50% 1RM负荷完成5组深蹲运动,每组20次,组间间歇2 min。深蹲运动前于肘正中静脉采集血样,测量大腿围、纵跳高度、膝关节活动幅度与肌肉酸痛程度,并于运动后即刻、24 h、48 h、72 h和96 h重复测试。ELISA法检测血清CK-MM、Mb与血浆IL-6,胶乳增强免疫比浊法检测血清CRP。结果：与安慰剂组被试相比,补充亮氨酸显著降低了亮氨酸组被试运动后延迟性肌肉酸痛水平、大腿中段周长及血清CK-MM、Mb、CRP与血浆IL-6含量,而深蹲1-RM值、纵跳高度及膝关节ROM组间差异则并无统计学意义。结论：1）每千克体重150 mg剂量亮氨酸能够削弱抗阻运动所导致的骨骼肌损伤与疼痛,该效应可能与对炎症反应的抑制有关,且推测亮氨酸对骨骼肌蛋白质代谢平衡的调节作用在其中亦有贡献;2）该剂量亮氨酸不能明显促进工作肌机能恢复。  相似文献   

Specific tackling situations affect the biomechanical demands experienced by rugby union players     

Elena Seminati  Dario Cazzola  Ezio Preatoni  Grant Trewartha 《Sports biomechanics / International Society of Biomechanics in Sports》2017,16(1):58-75

Tackling in Rugby Union is an open skill which can involve high-speed collisions and is the match event associated with the greatest proportion of injuries. This study aimed to analyse the biomechanics of rugby tackling under three conditions: from a stationary position, with dominant and non-dominant shoulder, and moving forward, with dominant shoulder. A specially devised contact simulator, a 50-kg punch bag instrumented with pressure sensors, was translated towards the tackler (n = 15) to evaluate the effect of laterality and tackling approach on the external loads absorbed by the tackler, on head and trunk motion, and on trunk muscle activities. Peak impact force was substantially higher in the stationary dominant (2.84 ± 0.74 kN) than in the stationary non-dominant condition (2.44 ± 0.64 kN), but lower than in the moving condition (3.40 ± 0.86 kN). Muscle activation started on average 300 ms before impact, with higher activation for impact-side trapezius and non-impact-side erector spinae and gluteus maximus muscles. Players’ technique for non-dominant-side tackles was less compliant with current coaching recommendations in terms of cervical motion (more neck flexion and lateral bending in the stationary non-dominant condition) and players could benefit from specific coaching focus on non-dominant-side tackles.  相似文献   

Tribute to Dr Jacques Rogge: muscle activity and fatigue during hiking in Olympic dinghy sailing     

Jan G. Bourgois  Jasmien Dumortier  Margot Callewaert  Bert Celie  Carlo Capelli  Gisela Sjøgaard 《European Journal of Sport Science》2017,17(5):611-620

‘A tribute to Dr J. Rogge’ aims to systematically review muscle activity and muscle fatigue during sustained submaximal quasi-isometric knee extension exercise (hiking) related to Olympic dinghy sailing as a tribute to Dr Rogge’s merits in the world of sports. Dr Jacques Rogge is not only the former President of the International Olympic Committee, he was also an orthopaedic surgeon and a keen sailor, competing at three Olympic Games. In 1972, in fulfilment of the requirements for the degree of Master in Sports Medicine, he was the first who studied a sailors’ muscle activity by means of invasive needle electromyography (EMG) during a specific sailing technique (hiking) on a self-constructed sailing ergometer. Hiking is a bilateral and multi-joint submaximal quasi-isometric movement which dinghy sailors use to optimize boat speed and to prevent the boat from capsizing. Large stresses are generated in the anterior muscles that cross the knee and hip joint, mainly employing the quadriceps at an intensity of 30–40% maximal voluntary contraction (MVC), sometimes exceeding 100% MVC. Better sailing level is partially determined by a lower rate of neuromuscular fatigue during hiking and for ≈60% predicted by a higher maximal isometric quadriceps strength. Although useful in exercise testing, prediction of hiking endurance capacity based on the changes in surface EMG in thigh and trunk muscles during a hiking maintenance task is not reliable. This could probably be explained by the varying exercise intensity and joint angles, and the great number of muscles and joints involved in hiking.

Highlights

• Dr Jacques Rogge, former president of the International Olympic Committee and Olympic Finn sailor, was the first to study muscle activity during sailing using invasive needle EMG to obtain his Master degree in Sports Medicine at the Ghent University.

• Hiking is a critical bilateral and multi-joint movement during dinghy racing, accounting for >60% of the total upwind leg time. Hiking generates large stresses in the anterior muscles that cross the knee and hip joint.

• Hiking is considered as a quasi-isometric bilateral knee extension exercise. Muscle activity measurements during sailing, recorded by means of EMG, show a mean contraction intensity of 30-40% maximal voluntary contraction with peaks exceeding 100%.

• Hiking performance is strongly related to the development of neuromuscular fatigue in the quadriceps muscle. Since maximal strength is an important determinant of neuromuscular fatigue during hiking, combined strength and endurance training should be incorporated in the training program of dinghy sailors.

  相似文献