Effect of passive motion of from lower extremity on muscle fatigue when the back under head-down tilting / 医用生物力学

ABSTRACT

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 selected. 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 frequency 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/min, the variation of MF became irregular. In the vibration mode, the MF increased with the increase of head-down tilting angle and was larger than that in the static mode. Conclusions In the static mode, the muscle fatigue increased with the head down tilting angle increasing; in the vibration mode, smaller head-down tilting angle should be selected to achieve better treatment 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.