維持平衡是一項很重要且很基本的技巧，如何利用身體肢段維持平衡更是一個很重要的課題。過去的研究大多著重在下肢的探討，鮮少討論到上肢，由於進行平衡動作時上肢並非固定不動，故也應該一併被考慮。本研究目的為探討個體在受到擾動時，上肢擺動與否對恢復平衡所造成的影響。實驗對象為健康成年男性，分為上肢不固定組(arm swing, AS)和上肢固定組(arm constrained, AC)，受試者站立於一塊測力板上進行平衡恢復動作，並收集動力學資料；運動學資料則利用動作捕捉系統取得。動作過程中不可使用跨步的方式來恢復平衡，腳尖不能離地但腳跟可以離地。實驗結果顯示，上肢不固定組恢復平衡的成功率較高、恢復平衡時間較短，代表恢復平衡過程中有上肢的參與的確可以使個體更容易更快速的恢復平衡，也可以讓個體處於可以進行下一項動作的狀態以避免受傷。雖然手臂對於降低地面反作用力的幫助並不明顯，但似乎可以有較好的平衡調節機制，所以即使在傾斜角度變大時地面反作用力並不會顯著增加。本研究定義動作過程中膝關節彎曲大於30度為膝關節策略，上肢固定組使用膝關節策略的比例很高，即沒有上肢參與時，膝蓋彎曲成為恢復平衡的主要方法之一。除此之外，經由實驗中觀察，個體間平衡動作的差異性很大，受試者所使用的平衡策略皆有差異。由本研究可以證實上肢對於恢復平衡動作是有幫助的。上肢僅為身體肢段其中的一部分，如何使身體各肢段之間產生更好的協調作用，需要透過訓練以及不斷地練習。

The ability to maintain balance is an important skill in daily life. Although participation of the arms has been reported in balance recovery, previous researches have focused extensively on lower limb strategies. The aim of this study was to investigate whether the arms could influence standing balance recovery with the hypothesis that enhanced performance could be achieved with unconstrained arm motions. Participates were released from three forward-lean angles and regained balance without moving the forefoot under arm swing (AS) and arm constrained (AC) conditions. Higher success rate and shorter recovery time were found in balance recovery with arm swing. Unlike the significant increases in ground reaction forces (GRF) between adjacent lean angles in AC, less (or no) significant differences between different lean angles in AS conditions implied the arms’ role in reducing GRF increase caused by the same external disturbances. Furthermore, greater lean angles increased difficulty in balance recovery, making the knee strategy (in addition to the existing ankle and hip strategies) more necessary and the influences of arms less significant. It was concluded that arm swing can indeed enhance standing balance recovery performances.

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