| Summary: | 碩士 === 國立嘉義大學 === 體育與健康休閒研究所 === 97 === The influence of whole body vibration at different accelerations and knee flexion angles on EMG activation and co-contraction of the lower limbs
Song, Guang-Yu
Graduate Institute of Physical Education, Health, and Leisure Study
National Chiayi University
Abstract
Whole body vibration (WBV) could improve muscle strength and power immediately after intervention or in long term training. The vibration platform was used to transduce oscillations from feet up to human body and can produce approximate 0.7~4 times of gravitational acceleration (g value) (1g=9.8m/s2). To the best of knowledge, few studies have discussed the effects of different g values on human body during WBV stimulations. The squat position was commonly suggested while undergoing the WBV stimulations. However, under that squat position, the influence of WBV on the muscle activations and co-contraction of lower extremity at different knee flexion angles were unclear. The purpose of this study was to analyze the muscle activation levels and co-contraction ratios of vastus medium (VM) and bicepes femoris (BF) at different knee angles and g values during WBV stimulations.
Twenty healthy college students (11 male and 9 female) were recruited in this study. Subjects were asked to take Non-Vibration (NV) and WBV at different levels (0.98g, 2.52g, 3.72g, 5.61g) with knee flexed at 45, 60, 90 degrees. EMG signals were recorded simultaneously during NV and WBV. Two-way ANOVA with repeated measures was used to compare EMG levels and co-contraction ratio at difference knee angles and g values. WBV EMG activation level of BF was significantly higher than NV when knee flexed at 60 degrees (0.98~3.72g) and 45 degrees (0.98~5.61g) during WBV stimulations. WBV EMG activation level of VM was significantly higher than NV at 0.98g and 2.5g when knee flexed 45 degrees.
The VM and BF muscles activation could be significantly increased by appropriate vibration stimulation and the activation levels were mainly affected by knee flexion angles. The results of this study suggested that combination of squat position at knee flexion 45 degrees with 0.98/2.52 g WBV stimulations could have better effects on enhancing lower extremity muscle activations.
|
|---|
