坐到站為日常生活中最常進行的活動，也是關乎移動與行走能力的基礎。穩定的從坐姿轉換成站立是與重心能否順利轉移到站立時支持面的底面積內有關，而老人族群因老化，可能會出現異於年輕族群所採用的動作策略來完成此動作。本研究的主旨是透過分析老年族群與年輕族群在進行坐到站過程中，整體重心轉移的差異，並比較重心與支持底面積間隔距離和頭部與膝蓋間隔距離相關性，以作為日後教導老年族群執行站立的簡單易懂方法。共計26位健康老年受測者與26位健康年輕受測者參與本研究案，受測者被要求進行三次坐到站的活動，研究者透過貼在受測者身上之反光球藉由六台紅外線攝影機之動作分析系統同步收集運動學資料。結果發現在站立初期離開椅面之前，老年人會先進行軀幹向前彎曲，將整體重心透過身體前傾的動作，帶到雙腳的支持底面積之內，以降低起身時平衡能力的干擾，且會利用軀幹前傾所產生的移動動量，來彌補膝關節伸直站立時所需的動量。此一「穩定策略」動作亦和頭部與膝蓋間隔距離變化有明顯的相關性。臨床治療師可透過此相關性來教導自行坐到站有困難的老年族群完成站立的動作，並且能有效地預防跌倒的意外。

Sit-to-stand (STS) movement is the most common activity of daily living. It also is related to the foundation of mobility and stability. Sucessful transitional movement  om a si ing position to the upright posture is related to the motion of the center of mass (COM) fell within the area of base of support (BOS). However, the elderly due to aging process may appear di erent strategies of the STS movement in comparsion with young people.  erefore, the purpose of this study was to analyze the differences of COM movement between the elder and young people during STS, and compare the relationship between the COM-BOS separation distance and head-knee separation distance. Twenty-six healthy old people and twenty-six healthy young people participated in this study. Subjects were asked to perform a STS movement for three times. Researchers recorded the kinematic variables from the re ective markers ac ached on the subject’s body and a six in a-red camera motion analysis system was used to record kinematic data synchronically.  e results indicated that during the beginning of STS, elderly people forward  exed their trunk to bring their COM within the region of BOS with less balance disturbance prior to seat off. With this trunk forward movement, elderly people gained this additional forward momentum to compensate the knee extension moment to initiate a standing. This stability strategy had significant correlation with the head-knee separation distance. Clinical therapists could use this relationship as a guideline to teach the elderly people who might have di culty performing STS, and prevent fall accidents e ectively.