視障生下階梯動作肌肉勁度調節能力與肌電現象之研究

Leg stiffness regulation and emg activities of person with visual impaired during downward stepping

目的：本研究透過比較視障大學生與正常人在下階梯動作過程中，下肢肌肉勁度調節能力的差異，以期了解視覺對神經肌肉控制以及肌肉勁度調節的影響。方法：以10名一般生和10名視障生為實驗參加者。使用Peak Performance運動影像分析系統、AMTI測力系統及Biovision肌電測量系統，分別對實驗參加者下階梯動作的運動學參數、地面反作用力及肌電活動狀況進行紀錄。相關參數以二因子變異數分析 （two-way ANOVA）進行統計，統計的顯著水準定為a=.05。結果：一、視障生著地前肌肉活化較一般生低。二、視障生著地時肌肉活化程度比一般生少。三、視障生著地時下肢關節彎曲限度小。四、視障生比一般生下肢勁度小。結論：在視障生與一般生兩種不同組別中，我們可以發現視障生在著地時的下肢勁度、角勁度均比一般生小且著地前肌電活動亦較小，這表示視障生在下階梯這種動作條件下，因無視覺回饋，會降低辨別與偵測環境的能力，所以著地前期的肌電預先活動會有偏小現象以致下肢勁度、角勁度調節表現不如一般生。也由於視障生視力的不足，導致實施動作時無法提供訊息給中樞神經系統，而造成動作表現能力下降。

Purposes: The purpose of this study was to analyze variance on the lower body muscular stiffness and EMG activity of contact and pre-contact between visually impaired students and healthy vision students on the process of movement for walking down stairs to identify the effects of eyesight for neuromuscular activation control and muscular stiffness adjustment. Method: Ten normal vision students and Ten visually impaired students were asked to perform the step-down walking from different heights: 20, 30 and 40㎝. AMTI force platform, Biovision system and Peak Performance high-speed camera were used synchronizely to record the ground reaction force, EMG signals and the video image of the movements Leg muscular stiffness was defined as: The ratio of ground reaction force at the transition from eccentric to concentric contraction and vertical displacement of center of gravity (Fmax / Lmax). The statistics is use two-way ANOVA to determine the variances with alpha level of .05. Results: According to the results analyzed, we concluded that this phenomenon shows that the ability of stiffness regulation of the normal one is more efficient than that of impaired ones. During downward stepping, the leg stiffness and the angular stiffness of visually impaired students were less than normal vision students. Conclusion: There is a sign of increase of leg stiffness and angular stiffness as the escalation of altitude. The myoelectric activities (EMG) of pre-contact for gastrocnemius lateral head of visually impaired students were smaller than those of normal ones. The myoelectric activities (EMG) of contact phase for rectus femoris , tibialis anterior and gastrocnemius lateral head of visually impaired students were smaller than those of normal ones. There is a sign of increase of IEMG as the escalation of altitude.