動態動作條件下老年人下肢肌肉勁度與肌電現象之研究

The Leg Stiffness and EMG Activities in Elderly during Dynamic Movement

本研究主要目的是要探討老年人動態肌力、肌肉勁度因老化而產生的變化，並且發展一種可以簡易評估老年人動態肌力、肌肉勁度的方法。受試者包括10名健康成年男性（平均年齡24.3±2.4）和10名健康且有運動習慣的男性老年人（平均年齡68.6±5.5）。本研究以Peak Performance高速攝影機（120Hz）、Kistler測力板（1200Hz）和Biovision肌電圖儀（1200Hz），同步記錄直立垂直跳動作（Counter Movement Jump，CMJ）時的下肢各關節運動學、地面反作用力和肌電圖參數。研究結果顯示，在最大用力垂直跳CMJ之動態動作過程中，老年人離心下蹲末期的地面反作用力、離心下蹲期的肌電活動（積分肌電與平均肌電振幅）、向心蹬伸期的肌電活動以及最大地面反作用力明顯比年輕人差，因此，老年人肌肉所能調控產生之動態性下肢肌肉勁度與肌力表現皆明顯較年輕人差，這意謂著老化使得神經肌肉系統調節能力與牽張反射能力下降，肌肉活性降低。透過垂直跳此種簡易的動態性動作，可以作為檢測老年人下肢動態肌力與肌肉勁度調控能力的方法。The purpose of present study was to investigate the changes of muscular strength and ability of leg stiffness regulation during maximal Counter-Movement-Jump (CMJ), and to develop an easy-use method to estimate the muscular strength and leg stiffness for elderly. Ten healthy aged people (age: 68.6±5 years; height: 165.3±4.4cm; mass: 61.7±9.3kg) and 10 students (age: 24.3±2years; height: 171.5±4.6cm; mass: 65.9±8kg) volunteered as subjects. Kistler force platform (1200Hz), Peak high-speed camera (120Hz) and Biovision EMG system (1200Hz) were used synchronously to record the ground reaction force, the kinematic and EMG parameters during the subjects performed maximal CMJ. The results revealed that the ground reaction force at the transition from eccentric to concentric contraction, the EMG activities in eccentric contraction and concentric contraction phase was significantly smaller for the elderly. The ability of leg stiffness regulation and the dynamic reactive strength for elderly was less than for the young subjects. These results indicated that the regulation and reflex ability of neuromuscular system would decrease with aging. It is suggested that the dynamic CMJ could be an easy-use test method to estimate the strength and leg stiffness for aged people.