人体头低脚高仰卧时下肢被动运动对背部肌肉疲劳的影响

Effect of passive motion from lower extremity on muscle fatigue when the back under head-down tilting

目的研究人体头低位状态下肢被动运动对背部主要肌肉肌电(electromyogram,EMG)活动性的影响。方法选取30名健康受试者,分析竖脊肌和斜方肌在不同头低位角度(0°、10°、20°、27°)下静止状态、120次/min和140次/min足部摆动模式和680次/min足部颤动模式下EMG变化趋势。结果在头低位静止状态时,4种头低位角度下中位频率(media frequency,MF)随角度增加均呈下降趋势;摆动模式下,4种头低位角度的MF值均小于静止状态,且当摆动速度为120次/min时,MF值随角度增加而减小;速度为140次/min时,MF值无规律性变化。颤动模式下,MF值随头低位角度增大而增大,且均大于静止状态。结论静止状态下,肌肉疲劳程度随头低位角度增加而增加;颤动模式下应选择较小的头低位角度可更好达到锻炼治疗效果,摆动模式下可选择较大的头低位角度有助于较好达到锻炼治疗效果。此外,为避免肌肉过度疲劳造成劳损,摆动速度应不大于120次/min。

Objective To study the effect of passive motion from lower extremity on electromyography （EMG） activity of major muscles when the back under head-down tilting state. Methods Thirty healthy subjects were se- lected. The EMGs of erector spinal and trapezius muscles were recorded and analyzed when human body was under head-down tilting at angel of 0°, 10°, 20° and 27° in static mode, respectively, in sway mode （along the axis of Z with frequencies of 120 and 140/min, respectively） and in vibration mode （along the axis of Y with fre- quency of 680/min） with the help of multifunctional test bed. Results In the static mode, the median frequency （MF） decreased with the increase of head-down titling angle; in the sway mode, the MF at each of 4 head-down tilting angles was smaller than that in the static mode. When the frequency was 120/min, the MF decreased with head-down tilting angle increasing, but when the frequency reached 140/rain, the variation of MF became irregu- lar. In the vibration mode, the MF increased with the increase of head-down tilting angle and was larger than thatin the static mode. Conclusions In the static mode, the muscle fatigue increased with the head-down tilting an- gle increasing; in the vibration mode, smaller head-down tilting angle should be selected to achieve better treat- ment effect; but in the sway mode, larger head-down tilting angle would be better, and the sway frequency should be set lower than 120/min to avoid potential damage due to excessive muscle fatigue.