不同高度跳深动力学及下肢肌肉预激活调节

Kinetics and Pre-activity Modulation of Lower Extremity Muscles within Different Heights of Drop Jump

目的:采集不同高度跳深训练动作动力学数据,测量自不同高度平台下落着地前下肢肌肉活性,比较不同高度对下肢肌肉预激活调节的影响。方法:对未经系统跳深训练的16名健康男性受试者进行低、最佳、高三种平台高度的跳深练习,记录每次跳深动作着地前150ms内腓肠肌内侧头、股直肌、股外侧肌、胫骨前肌、股二头肌的表面肌电信号,计算积分肌电和最大振幅。记录跳深动作过程腾空时间和着地支撑时间,计算平均输出功率。结果:最佳高度条件下腾空时间最长,低平台条件下跳深输出功率最高。除腓肠肌内侧头以外,其他肌肉预激活均随着跳深平台高度增加而增加。多数肌肉预激活显著性差异出现在低-高之间,低-最佳、最佳-高之间肌肉预激活差异性不显著。结论:高于最佳高度时下肢肌肉预激活与地面反作用力不协调。跳深输出功率是较恰当的下肢超等长训练参数。实践中采用跳深法对下肢肌肉进行爆发力训练时,宜以最佳高度或低于最佳高度的形式。

Objective：The purpose of this study was to test kinematics and kinetics variables and measure surface electromyography （SEMG） of lower extremity muscles,and determine modulation of pre-activity related to drop jump（DJ） with different heights.Methods：Sixteen healthy young males without experience in deep jumps training,who participated in the study,from three different heights （low,optimal,high）.SEMG device was used to estimate muscle activity （integral EMG signal-iEMG and maximal amplitude of EMG-AmaxEMG） of five muscles （tibialis anterior-TA,gastrocnemius medialis-GM,rectus femoris-RF,vestus lateralis-VL,biceps femoris-BF） within 150ms before touchdown.Contact time and flight time of DJ were measured to be used in output power calculation.Result：There is long flight time in drop jump of optimal drop height and high output power in drop jump of low drop height.All muscles,except GM,showed systematic increase in pre-activity when platform height was raised.For most of the lower extremity muscles,the most significant differences were between values of pre-activity obtained for low and high platforms.The amount of muscle pre-activity in DJ from the heights above and beneath the optimal one did not differ significantly from that generated in DJ from the optimal drop height.Conclusion：DJ from the heights above the optimal one are not adequate for adjusting muscle activity for the impact of ground reaction force.We recommend the DJ power output as the main criteria to train lower extremity for plyometric training purposes.DJ from the optimal drop height or beneath the optimal one should be used as plyometric training method in practice to elevate muscle strengthower extremity.