The character of muscle endurance during isometric contraction

为探讨几种肌肉的肌电功率谱特征，对45名健康受试者（男22名，女23名）进行了120秒无支撑躯干保持试验。记录表面电极放置在每个竖脊肌在L1水平。使用ME3000P快速傅立叶变换频谱分析程序评估中值频率（MF）、平均功率频率（MPF）和过零率（ZCR）。所有背部肌肉疲劳指数的负斜率在男性比女性明显更陡。对10名偏瘫男性和10名健康男性进行了躯干保持试验，并对表面肌电功率谱进行了分析。采用表面肌电功率谱分析方法，对6名轮椅马拉松截瘫上级运动员和6名正常截瘫男子的肱三头肌耐力进行了研究。肱三头肌疲劳各项指标的负斜率，对照组均显著大于运动员组。我们的研究结果还表明，上级运动员的肌肉耐力高于对照组。

The purpose of our studies is to investigate the characters of several kinds of muscles using electromyographic (EMG) power spectral analyses.Forty-five healthy subjects (22 men and 23 women) were studied during an unsupported trunk holding test for 120 seconds. Recording surface electrodes were placed over each erector spinae muscle at L1 level. Median frequency (MF), mean power frequency (MPF) and zero crossing rate (ZCR) were evaluated using the ME3000P Fast Fourier Transform spectrum analysis program. The negative slopes of all indices of back muscle fatigue were significantly steeper in men than women. Our results also showed a higher muscle endurance in healthy adult women than in men.Ten hemiplegic men and ten healthy men were studied during a trunk holding test using surface EMG power spectrum analysis. The negative MF slope of the affected back muscle was not significantly different from that of the unaffected.The difference of triceps muscle endurance between six paraplegic superior athletes of wheel-chair marathon and six control paraplegic men were examined using surface EMG power spectrum analysis. The negative slopes of all indices of triceps muscle fatigue were significantly steeper in control than in athletes. Our results also showed a higher muscle endurance in superior athletes than in control men.