Electromyographic power spectial anelysis during isometric contiaction of the brachial muscle

目的与设计：应用表面肌电功率谱分析方法，探讨优秀轮椅马拉松截瘫运动员肱三头肌耐力特征。方法：采用体表电极对9名男性截瘫运动员和6名男性非截瘫运动员在50%最大自主收缩水平的右肱三头肌进行等距收缩时的肌电图测定。结果测量：使用ME3000P快速傅立叶变换频谱分析程序，用个人电脑计算肌电图中的中位数频率（MF）和平均工频（MPF）。计算MF与时间、MPF与时间的Pearson相关系数，以及MF和MPF的变化率。结果：MF和MPF随时间呈线性下降。运动员的负斜率分别为-8.9±4.6和-9.7±4.6 %/min，对照组的负斜率分别为-22.3±8.2和-21.2±6.4 %/min，且运动员负斜率绝对值显著小于对照组（p<0.05）。结论：肌电功率谱分析表明，运动员肱三头肌的耐力较强，因为其MF和MPF的下降幅度较小。

Objective and Design : To investigate the endurance features of triceps brachii muscles in elite paraplegic wheelchair marathon athletes using the surface electromyographic power spectral analysis. Method : Electromyograms of the right triceps brachii muscles during isometric contraction at the level of 50% maximal voluntary contraction were obtained by using surface electrodes from 9 male elite paraplegic wheelchair marathon athletes and 6 male paraplegic non-athletes as a control. Outcome Measures : Median frequency (MF) and mean power frequency (MPF) in the electromyograms were calculated with a personal computer using the ME3000P Fast Fourier Transform spectrum analysis program. Pearson's correlation coefficients between MF and time and between MPF and time, and the rates of changes in MF and MPF were calculated. Results : MF and MPF decreased with time linearly. The negative slopes of MF and MPF were -8.9±4.6 and -9.7±4.6 %/min for the athletes, and -22.3±8.2 and -21.2±6.4 %/min for the controls, and the absolute values of the negative slopes in the athletes were significantly smaller than those in the controls (p<0.05). Conclusion : The electromyographic power spectral analysis revealed that the triceps brachii muscles in the athletes are more endurable because of a smaller decrease in MF and MPF.