外加弹性紧身装置对田径运动员下肢肌力、疲劳与肌肉活动的影响

目的:利用下肢等动肌力测试,配合生物信号分析工具——肌电图与肌动图,探讨不同紧度的外加紧身装置对力量输出、疲劳表现以及肌肉活动的影响。方法:利用力量传感器和砝码测得紧身装置的张力-长度曲线,并据此选取紧度张力分别为66.4N和85.8N的中等和高等紧度负荷。由12名田径专项男运动员分别完成无紧身装置、中等紧度负荷和高等紧度负荷三种紧度条件下的测试,包括5秒最大等长收缩和两种速度(60°.s-1和300°.s-1)下的连续25次最大伸膝等动向心运动,并同步采集力量输出参数(力矩、功率、做功)、股直肌肌电和肌动信号(均方根振幅)。结果:三种紧度条件下峰值力矩、峰值功率、前5次平均功率和总做功量无显著性差异;在两种速度下的最大等动向心运动中,相比无紧度条件,高等紧度条件下最大力矩衰减更为缓慢,同时肌电振幅随着外加紧度增加(从无到高)呈显著递减趋势(P<0.05),但肌动振幅的变化却不明显。结论:紧身装置未改变下肢短时间收缩时的肌力和爆发力,然而通过增加一定范围的紧度能够帮助肌肉在募集更少运动单位的情况下维持相似的力量输出,进而对肌肉疲劳和长时间的运动表现产生积极的影响。

The Influence of External Elastic Compression on the Muscular Strength, Fatigue and Activity of Track and Field Athletes

Objective To quantify the effects of external compression on the muscular strength,fatigue,and activity through electromyography(EMG)and mechanomyography(MMG)during isokinetic muscle actions.Methods 66.4N and 85.8N tension-length curve(used as moderate and high compression,respectively) were obtained with standard weights through a force transducer.All subjects(n=12)performed 5 seconds of MVCs and 25 isokinetic knee extensions at 60 °.s-1 & 300°.s-1 with the two different compressions and without compression.The signals for strength production,EMG,and MMG amplitude(RMS) were collected simultaneously.Results No significant differences were found among three compressions for strength production;while there was a significant decrescence in the ratio of torque and overall rmsEMG(P<0.05)during performing isokinetic knee extensions at 60°.s-1 & 300°.s-1,comparing to the none compression.Conclusion Local elastic compression on lower extremity did not significantly improve isokinetic strength in a short period of time,but did positively affect on muscular fatigue by helping maintain long-term force production through recruiting lesser motor units during movements.