全身振動與身體姿勢對下肢肌肉影響探討

A study on effects of muscle of lower limb associated with whole-body vibration and body posture

鄭翔安(Xiang-An Cheng)

指導教授 ： 盧士一

中山醫學大學/健康管理學院/職業安全衛生學系碩士班/碩士(2016年)

摘要

全身振動的暴露被認定是身體健康風險主要因子之一，長期的暴露於全身振動工作場所會增加下背疼痛或椎間盤突出等疾病的機率，造成無法恢復之職業疾病。然而，許多研究也指出振動刺激對於人體具有多種正面效果，經常用來做為物理治療或臨床醫療與增加肌肉強度的訓練(WBVT)上，多年來振動對於肌肉能力的影響也一直是備感興趣的議題，其特色是全身振動平台能提供一重力加速度，並刺激本體感覺及運動神經，在治療或訓練時誘發肌肉伸張收縮，多數學者普遍認為此訓練方法可強化肌力和爆發力。在本研究，係利用經常使用的市售電動運動振動機，將膝蓋屈曲不同角度站立在全身振動平台並施以不同的頻率，而下肢肌肉的肌電訊號將被評估，以探討姿勢與頻率對於『肌肉活化』（Neuromuscular activation）與振動傳遞的影響。
實驗透過『表面肌電圖』(Electromyography, EMG)來評估下肢肌肉受到全身振動後的肌電反應。肌電反應是在肌肉收縮時，肌肉兩端的電位差所產生出來的肌電訊號，它可以依人體肌肉動作時收縮強度的多寡，讓細胞膜產生不同的電位差，其訊號也有不同的強度及特徵，本實驗由此判斷下肢肌肉負荷程度與肌肉疲勞。
研究結果顯示下肢肌肉對於膝蓋屈曲角度的改變有顯著的影響，尤其是作為支撐身體重量力矩的大腿肌群；而受到振動頻率影響最顯著的下肢肌肉為小腿肌，這可能是較接近振動源頭的關係；實驗情境中，有無施加振動對下肢肌肉肌電反應有顯著的影響；動態的情境肌電反應普遍高於靜態情境，但透過受測者主觀知覺施力評估可知兩情境分數相當接近，可能是因為動態情境作功較多且能夠不斷代謝氧氣等其他營養物質的緣故；透過頻率振幅合併分析法(Joint analysis of spectra and amplitude, JASA)可以評估下肢肌肉的疲勞程度與階段，在受測者主觀認為最疲勞的兩個情境(分別為50Hz的靜態膝蓋彎曲90度與動態膝蓋彎曲90度)，此兩情境皆可判別下肢肌肉可能位於疲勞的狀態。

關鍵字

全身振動 ； 肌電圖 ； 肌肉疲勞

並列摘要

Whole-body vibration exposure was identified as one of the major health risk factors. Long-term exposure to whole-body vibration in the workplace will increase the chances of lower back pain or disc herniation or other diseases, and result in unrecoverable of occupational diseases.
However, many studies also indicated that vibration stimulation for the human-body has a variety of positive effects, and which was often used in physical therapy or clinical treatment and increased muscle strength training (Whole-Body vibration training, WBVT). Over the years, vibration for the muscle ability of effects has also been the deeply-interested subject, which features that whole-body vibration platform can provide a gravitational acceleration, and stimulate proprioceptive sensory and motor nerves, while inducing muscle to stretch and contract in the treatment or training. Most scholars generally believe that this training method can enhance strength and power of muscles.
In this study, the frequently-used and commercially-available electric motion system vibrating machine was chosen, making the one stand on the whole-body vibration platform with knees flex at different angles and applying to different frequencies in the same time. Moreover ,the lower extremity electromyography signals were be evaluated that to explore the effects of position and frequency for the neuromuscular activation and the vibration transmission.
The experiment used electromyography(EMG) to assess the response of lower extremity muscle EMG after receiving whole-body vibration.
Electromyography response is arising by the electromyography signal which is produced by the potential difference at both ends of muscle when the muscle contracts. It can be according to the amount of contraction strength as body muscles action, to make cell membrane to produce a different potential difference. And the signals also have different strength and characteristics. On the basis of these, this experiment determine the extent of muscle load and muscle fatigue of lower extremity.
The results showed that lower extremity muscles have a significant effect on the changes of position, especially thigh muscles was regard as the support for human-body weight ,and the most obvious impact on the vibration frequency of lower extremity muscles is calf muscles. It may be the possible for the source of vibration closely. In an experiment, the exertion to the vibration or not have a significant influence in the response of lower extremity muscles electromyography. The response for electromyography of dynamic situations generally higher than static ones; nevertheless, with Rating of Perceived Exertion(RPE), we found that two situations scores were very close. It might due to dynamic situations make more act, and it could continue to metabolism the oxygen or other nutrients. Through joint analysis of spectrum and amplitude (JASA), it could evaluate the fatigue and stages of lower extremity muscles, the subjects subjectively considered the two most fatigued situations(it divided into knees bent 90 degrees of static and dynamic situations by 50Hz ),and there were able to determine lower extremity muscles, which might be located in the state of fatigue.

並列關鍵字

whole-body vibration ； EMG ； muscle fatigue

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