Background. Simultaneous tiredness of two or more muscles around a joint can be defined as coordinated fatigue (cofatigue) and might occur between agonist and antagonist muscles, and vary according to the level of sporting activity levels or gender. Objectives. The aim of this study was to determine the levels of coordinated fatigue in agonist and antagonist muscles during squat-press exercise. Methods. Twenty athletes and twenty sedentary subjects participated in the study. Surface electromyography signals of the rectus femoris, vastus lateralis obliquus, biceps femoris and semitendinosus muscles were recorded at the squat press position for 15 seconds during isometric contraction. Measurements were repeated five times and a 2-minute rest period was allowed between repetitions. After erroneous EMG elimination, movement artefacts were removed by using a 20 Hz high-pass Butterworth filter. Then, as a wellrecognized fatigue index, the median frequency (MF) of each filtered middle part of the EMG signal (5 to 10 s. of contraction) was calculated, given that it is known that the MF decreases during isometric contractions. Finally, each MF-based co-fatigue index was calculated by dividing the mean RF and VLO median frequencies by the mean ST and BF median frequencies. The cumulative co-fatigue values of “male vs. female” and “sedentary vs. athlete” comparisons were performed by using a two-sided Student t-test with a Bonferroni correction. Results. There was a statistically significant (Bonferroni corrected p-value < 0.05) difference between the mean female (1.57  0.53) and the mean male (1.23  0.17) co-fatigue values, while there was no statistically significant difference between the mean co-fatigue values of sedentary (1.51  0.52) and athlete (1.29  0.27) subjects. Conclusion. The offered co-fatigue indices might be useful for other sports, physiotherapy and related areas if sufficient scientific proof is accumulated.

中文翻译：

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蹲卧推运动中大腿激动和拮抗肌肉中基于肌电图的协调疲劳水平的确定

背景。关节周围两个或更多肌肉的同时疲劳可被定义为协调疲劳（同疲劳），可能发生在激动剂和拮抗肌之间，并根据体育活动水平或性别而变化。目标。这项研究的目的是确定深蹲运动中激动剂和拮抗剂肌肉的协调疲劳水平。方法。20名运动员和20个久坐的受试者参加了这项研究。在等距收缩过程中，蹲下按压位置记录了股直肌，股外侧斜肌，股二头肌和半腱肌的表面肌电信号，持续15秒。重复测量五次，两次重复之间允许有2分钟的休息时间。错误排除EMG之后，通过使用20 Hz高通巴特沃斯滤波器去除运动伪像。然后，作为已知的疲劳指数，计算出EMG信号的每个滤波中间部分（收缩5到10 s。）的中值频率（MF），前提是已知MF在等距收缩过程中会降低。最后，通过将平均RF和VLO中值频率除以平均ST和BF中值频率来计算每个基于MF的共疲劳指数。通过使用带有Bonferroni校正的双面学生t检验，进行“男性与女性”和“中级与运动员”的累积同疲劳值比较。结果。女性平均疲劳度（1.570.53）和男性平均疲劳度（1.230.17）之间存在统计学差异（Bonferroni校正p值<0.05），久坐者（1.510.52）和运动员（1.290.27）的平均共同疲劳值之间无统计学差异。结论。如果积累了足够的科学依据，则所提供的共同疲劳指数可能对其他运动，物理治疗和相关领域有用。