BACKGROUND Musculoskeletal disorders are more prevalent among women than among men, which may be explained by aspects of motor control, including neuromuscular requirements and motor variability. Using an exploratory approach, this study aimed to evaluate sex differences in neuromuscular responses and motor variability during a repetitive task performed on 3 days. METHODS Thirty women and 27 men performed the non-fatiguing, repetitive, 1-h screwing task. For neuromuscular responses, the mean and difference values of static, median, and peak percentile muscle activity levels (normalized to a reference voluntary contraction force) and, for motor variability, the mean and difference values of relative and absolute cycle-to-cycle variability across days were compared between both sexes for each muscle. A mixed-design analysis of variance was used to assess differences between both sexes. RESULTS The non-fatiguing character of the screwing task was confirmed by the absence of decreased force levels in maximal voluntary contractions performed before and after the task and by absence of electromyographic signs of muscle fatigue. The static and median muscle activity levels tended to be higher among women (on average 7.86 and 27.23 %RVE) than men (on average 6.04 and 26.66 %RVE). Relative motor variability of the flexor and biceps muscles and absolute motor variability of both upper arm muscles were lower in women (on average 0.79 and 29.70 %RVE) than in men (on average 0.89 and 37.55 %RVE). The median activity level of both upper arms muscles tended to decrease within days among women (on average - 2.63 %RVE) but increase among men (on average + 1.19 %RVE). Absolute motor variability decreased within days among women (on average - 5.32 to - 0.34%RVE), whereas it tended to decrease less or increase within days among men (on average - 1.21 to + 0.25 %RVE). CONCLUSION Women showed higher levels of muscle activity and lower initial relative and absolute motor variability than males when performing the same occupational task, implying women may have a higher risk for developing disorders and point to both sexes using different intrinsic motor control strategies in task performance. Clearly, biological aspects alone cannot explain why women would be at higher risk for developing disorders than men. Therefore, a wider range of individual and environmental factors should be taken into account for optimizing work station designs and organizations by taking into account sex differences.

中文翻译：

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响应非疲劳性重复性拧紧任务，肌肉活动和运动变异的性别差异。

背景技术肌肉骨骼疾病在女性中比在男性中更为普遍，这可以通过运动控制的方面来解释，包括神经肌肉需求和运动变异性。本研究采用探索性方法，旨在评估在3天的重复任务中神经肌肉反应和运动变异性的性别差异。方法30名女性和27名男性完成了无疲劳，重复性的1小时拧紧任务。对于神经肌肉反应，静态，中位和峰值百分位数肌肉活动水平的平均值和差异值（标准化为参考自愿收缩力），对于运动变异性，相对和绝对循环间差异的平均值和差异值比较两天之间每只肌肉的性别。混合设计的方差分析用于评估男女之间的差异。结果拧紧任务的无疲劳特性是通过在任务之前和之后进行的最大自发性收缩中力水平的降低以及肌肉疲劳的肌电信号的缺乏而得到证实的。女性（平均RVE为7.86和27.23％）的静态和中值肌肉活动水平往往高于男性（平均RVE为6.04和26.66％）。女性（平均RVE为0.79和29.70％）的屈肌和二头肌相对运动变异性以及上臂的两个绝对运动变异性均低于男性（平均EVE为0.89和37.55％）。女性上臂的平均活动水平倾向于在几天之内下降（平均-2。RVE为63％），但男性则有所增加（平均+ 1.19％RVE）。女性的绝对运动变异性在几天之内下降（平均RVE-5.32至-0.34％），而在男性中，它在几天之内趋于减小或增加（平均-RVE-1.21至+ 0.25％）。结论在执行相同的职业任务时，女性表现出比男性更高的肌肉活动水平和更低的初始相对运动和绝对运动变异性，这意味着女性在执行任务时使用不同的内在运动控制策略可能会出现疾病的风险更高，并且指出两性。显然，仅从生物学方面来讲，不能解释为什么女性比男性更容易患上疾病。因此，