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目的:运用表面肌电技术了解疲劳状态下颈部肌肉的活动变化规律,为颈部肌肉疲劳提供理论依据。方法:16名无颈部疾病的健康青年男性志愿者,分别在屈、伸、左侧屈和右侧屈4个运动方向上完成60%最大随意收缩力(Maximal Voluntary Contraction,MVC)的等长收缩,直至力竭。评价指标包括平均肌电值(Averaged Electromyographic Signal,AEMG)、平均功率频率(MPF)、复杂度(Lempel-Ziv,C(n))以及确定性线段百分比(Determinism%,%DET)。结果:1)在60%MVC负荷下,AEMG随着负荷时间的延续逐渐增加,MPF及C(n)随负荷时间的延长逐渐减小,而呈逐渐增加的趋势。2)在疲劳实验中进行屈颈运动时,胸锁乳突肌的MPF下降斜率与其他方向及其他肌肉有显著性差异(P<0.05),C(n)和%DET上体现出较为明显的规律性。结论:各肌肉在对应运动方向上担任主动肌时容易产生疲劳,胸锁乳突肌尤为明显。而在疲劳性屈颈运动时主动肌胸锁乳突肌和拮抗肌头夹肌均较易产生疲劳,sEMG信号的周期化程度随疲劳积累而增加。
OBJECTIVE: To understand the changes of muscle activity in the neck under fatigue using surface electromyography (EMG) technique and to provide a theoretical basis for neck muscle fatigue. METHODS: Twenty-six healthy young male volunteers without neck disease were given equal length of 60% maximal voluntary contractility (MVC) in 4 directions of flexion, extension, left flexion and right flexion, respectively Shrink, until exhausted. The evaluation criteria included Averaged Electromyographic Signal (AEMG), Mean Power Frequency (MPF), Complexity (Lempel-Ziv, C (n)) and Determinism% (% DET). Results: 1) Under the load of 60% MVC, AEMG increased gradually with the increase of load time. The MPF and C (n) gradually decreased with the increase of load time, but gradually increased. 2) During the fatigue test, the slope of MPF decline was significantly different from other directions and other muscles (P <0.05), while C (n) and% DET were more obvious Regularity. Conclusion: Each muscle is prone to fatigue when acting as an active muscle in the corresponding direction of movement, especially in the sternocleidomastoid muscle. During fatigue flexion, the active muscle sternocleidomastoid muscle and antagonistic muscular myenteric muscle are more prone to fatigue, the degree of cyclical sEMG signal increases with fatigue accumulation.