徐明伟, 金龙哲, 于露, 刘建国, 张安琪. 长时间颈部前屈对颈部肌肉疲劳的影响[J]. 工程科学学报, 2019, 41(11): 1493-1500. DOI: 10.13374/j.issn2095-9389.2019.04.24.007
引用本文: 徐明伟, 金龙哲, 于露, 刘建国, 张安琪. 长时间颈部前屈对颈部肌肉疲劳的影响[J]. 工程科学学报, 2019, 41(11): 1493-1500. DOI: 10.13374/j.issn2095-9389.2019.04.24.007
XU Ming-wei, JIN Long-zhe, YU Lu, LIU Jian-guo, ZHANG An-qi. Effect of long-term bowing of the head on neck muscle fatigue[J]. Chinese Journal of Engineering, 2019, 41(11): 1493-1500. DOI: 10.13374/j.issn2095-9389.2019.04.24.007
Citation: XU Ming-wei, JIN Long-zhe, YU Lu, LIU Jian-guo, ZHANG An-qi. Effect of long-term bowing of the head on neck muscle fatigue[J]. Chinese Journal of Engineering, 2019, 41(11): 1493-1500. DOI: 10.13374/j.issn2095-9389.2019.04.24.007

长时间颈部前屈对颈部肌肉疲劳的影响

Effect of long-term bowing of the head on neck muscle fatigue

  • 摘要: 长期颈部前屈对颈椎造成严重影响。为定量评估长时间低头对颈椎疲劳造成的影响,选取20名健康受试者,保持低头角度40°~60°持续3 h。选择胸锁乳突肌,颈部夹肌和肩部斜方肌测量其表面肌电信号。经滤波、整流、振幅标准化等处理后,对每60 s的肌电值进行积分和求其平均功率频率。研究发现,积分肌电值的波动变化具有规律性,首次增大后的减小表征肌肉进入疲劳状态;不同肌肉的平均功率频率(mean power frequency,MPF)值具有明显差异,决定着该肌肉疲劳耐受性的持续时间,且在整个颈部前屈过程中MPF并非简单的线性关系。提出用MPF的导数来提取疲劳特征,用窗口化的MPF负数累积判定肌肉疲劳。结果表明,MPF负数累积能很好地判断肌肉疲劳,胸锁乳突肌在20 min内出现最终疲劳,而颈部夹肌和肩部斜方肌在20 min左右出现了短暂性疲劳,随后在75~100 min时又出现了最终疲劳。因此建议持续颈部前屈时长不超过20 min。

     

    Abstract: Long-term neck flexion posture is a common awkward posture resulting from long-term head-down work, long-term looking at a computer screen, and long-term playing with a mobile phone. Fatigue and chronic injury of cervical muscles are easily caused by long-term bowing of the head. Long-term bowing of the head to play with a mobile phone causes injury to the cervical spine. Long-term neck muscle contraction is an important cause of fatigue and chronic injury of the neck muscles and tissues. Therefore, it is of significance to analyze the changes of muscle activity during long-term neck muscle contraction and to determine the time threshold of neck muscle fatigue to reduce the damage caused by neck muscle fatigue. To quantitatively evaluate the effect of long-term head-down playing with a mobile phone on cervical spine fatigue, 20 healthy subjects were selected and kept the head-down angle between 40° and 60° for 3 h. On the basis of the analysis of cervical spine muscle architecture and anthropometry, the surface electromyography (sEMG) of the sternocleidomastoid, cervical gripper, and shoulder trapezius muscles was recorded. The original sEMG data were processed by filtering, rectifying, and amplitude standardization. The EMG values every 60 s were integrated, and their mean power frequency (MPF) was calculated. Results show that the fluctuation of the integral EMG is regular and the decrease after the initial increase indicates that the muscle is in the fatigue state. The MPF values of different muscles have obvious differences, which determine the duration of fatigue tolerance of the muscle. Moreover, the MPF does not exhibit a simple linear relationship during the entire bowing process. The results also show that negative MPF accumulation can be used to assess neck muscle fatigue. The sternocleidomastoid muscle is in the fatigue state in 20 min, whereas the cervical gripper and shoulder trapezius muscles are temporarily fatigued in approximately 20 min and in the final fatigue state in 75–100 min. Therefore, it is suggested that the duration of continuous bowing should not exceed 20 min.

     

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