Laboratory for Ergonomics and Work-related Disorders, Center for Sensory-Motor Interaction, Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7 D-3, 9220 Aalborg East, Denmark.
Eur J Appl Physiol. 2013 Jan;113(1):175-82. doi: 10.1007/s00421-012-2425-6. Epub 2012 May 26.
This study aimed at investigating gender difference in the coordination of the subdivisions of the trapezius muscle during a repetitive box-folding movement task. Twenty-two healthy volunteers (11 males and 11 females) performed the repetitive box-folding task for 34 min. During the task, perceived exertion and surface electromyographic (EMG) signals from the upper, middle, and lower trapezius subdivisions were recorded. Absolute and normalised root mean square (RMS) values as well as normalised mutual information (NMI) values were calculated to assess, respectively, activation levels within muscle subdivisions and functional connectivity among subdivisions. Females compared with males were characterised by higher normalised RMS values in the upper trapezius (P < 0.05) and higher NMI values within the upper-middle subdivision pair (P < 0.05) during repetitive box-folding. The elevated normalised level of activation of the upper trapezius as well as the enhanced functional connectivity among upper-middle trapezius subdivisions underlined that females adopted a different motor strategy than males did during a dynamic repetitive task. Such differences within and among muscle subdivisions may not be a favourable trait and could partly contribute to the higher prevalence of musculoskeletal disorders reported in females.
本研究旨在探讨在重复纸箱折叠动作任务中斜方肌各亚部的协调性的性别差异。22 名健康志愿者（11 名男性和 11 名女性）完成了 34 分钟的重复纸箱折叠任务。在任务过程中，记录了上、中、下斜方肌亚部的感知用力和表面肌电图（EMG）信号。分别计算绝对均方根（RMS）值和归一化均方根（RMS）值以及归一化互信息（NMI）值，以评估肌肉亚部内的激活水平和亚部间的功能连接。与男性相比，女性在重复纸箱折叠过程中，上斜方肌的归一化 RMS 值更高（P<0.05），中上斜方肌亚部间的 NMI 值更高（P<0.05）。上斜方肌激活水平升高以及中上斜方肌亚部间功能连接增强，表明女性在动态重复任务中采用了不同于男性的运动策略。肌肉亚部内和亚部间的这些差异可能不是一个有利的特征，并可能部分导致女性报告的肌肉骨骼疾病的更高患病率。
