下階梯動作會使步幅受到階梯的限制，同時需注意階梯位置及高度，因此會改變個體原有的動作型態，然而，太極拳運動強調動作較慢的重心轉移，屬於連續性及較低強度的活動，在運動的過程中也有別於其他有氧運動（如：慢跑、騎乘腳踏車、游泳），因此從事太極拳運動是否會改變日常生活動作中的動作型態，值得深入探討。目的：探討從事太極拳運動與健康中老年人於下階梯動作型態之差異。方法：本研究招募16名中老 年人，包含8名太極拳運動組與8名對照組。利用10臺Vicon攝影機（250 Hz）、Kistler 測力板（1000 Hz）和Noraxon無線肌電系統（1500 Hz），同步收集下階梯過程的全身動作、地面反作用力及肌肉活化情形。使用SPSS 20.0進行獨立樣本t考驗，比較兩組間之差異。結果：太極拳組於下階梯之時間較長（p ＜ .05）。制動期過程中，太極拳組於地面反作用力、負荷率及膝關節伸展力矩皆小於對照組（p ＜ .05）。推蹬期過程中，太極拳組髖關節屈曲力矩低於對照組、踝關節蹠屈力矩高於對照組及腓腸肌活化多於對照組（p ＜ .05）。結論：本研究發現太極拳組有助於減緩地面反作用力，降低下階梯過程中受傷的風險。

The movement of stair descent, such as step length, is limited by the width and height of stair. Therefore, the movement pattern during stair walking is altered by the stairs. Tai Chi emphasize slow and still shifting of the center of mass, which makes it a continuous and low-intensity activity, differing from other aerobic exercises (e. g., jogging, cycling, and swimming). Engage Tai Chi exercise can significantly improve the locomotion during daily life in the middle-elderly, which is worthy of discussion. Purpose: This study was to investigate the difference in stair descent patterm between Tai Chi practitioners and healthy middle-aged of the same age group. Methods: Eight healthy middle elderly with Tai Chi exercise experience were recruited as Tai Chi Group (TCG); and other eight healthy middle elderly with regular leisure exercise experiences were recruited as normal group (NG). A 10-camera Vicon system (250 Hz), a Kistler force plate (1000 Hz) and Noraxon EMG system (1500 Hz) were used to collect 3D kinematics, Kinetic and EMG data, respectively, during stair descent. All data were tested for independent sample t-test (a = .05). Results: The TCG used longer time for descent (p ＜ .05). During the braking phase, the TCG had lower ground reaction force, loading rate and knee joint extensor moment (p ＜ .05); During the push off phase, the TCG had lower hip flexor joint moment but higher ankle plantar flexor joint moment and gastrocnemius mean EMG amplitudes (p ＜ .05). Conclusions: Tai Chi exercise could mitigate the impact of the ground reaction force, and might decrease the rate of injury risk during descent.