肱二头肌离心和向心收缩的肌电信号特征

采用线性分析指标平均振幅、平均功率频率和非线性分析指标Lempel-Ziv复杂度、确定性线段百分比，分别对在5、10和15 kg 3种负荷水平下肱二头肌离心和向心收缩运动诱发肌肉疲劳过程中表面肌电信号的变化进行了分析.结果发现，表面肌电信号的线性和非线性指标的均值在离心和向心2种收缩类型间均存在显著差异（P<0.05），平均振幅和确定性线段百分比的均值在3种负荷水平间存在显著差异（P<0.05），而平均功率频率和 Lempel-Ziv复杂度的均值在3种负荷水平间无显著差异.线性和非线性指标的斜率在3种负荷水平间均存在显著差异（P<0.05），但在离心和向心2种收缩类型间仅有平均振幅存在显著差异（P<0.001）.实验结果为在疲劳过程中表面肌电信号的疲劳相关性指标的变化具有非疲劳特异性的观点提供了新的实验证据.

Surface electromyographic dynamics during biceps brachii eccentric and concentric contractions

Linear analysis(average electromyographic(AEMG) activity,mean power frequency(MPF)) and nonlinear analysis(Lempel-Ziv complexity,percent determinism(DET)) were applied to examine the surface electromyographic(sEMG) activities of biceps brachii in processes of eccentric and concentric contractions and among deferent load levels.Eleven male subjects performed eccentric and concentric contractions with three different load levels.The results showed that the differences of the mean values of both AEMG and DET were significant(P<0.05) between both the contraction types and the load levels.The mean values of both MPF and complexity changed significantly(P<0.05) between the contraction types but did not between the load levels.The slopes of AEMG changed significantly(P<0.001) between both the contraction types and the load levels.But the slopes of MPF, complexity and DET changed significantly(P<0.05) between the load levels but did not between the contraction types.New experimental evidence is provided in this study that the fatigue-related sEMG parameters during exercise are non-specific to muscle fatigue in nature.