太極拳運動是目前國內老年人最常從事的運動之一。太極拳運動對身體之效益已被廣泛探討，例如：心肺適能、肌力、平衡以及柔軟度等。在生物力學方面的研究主要集中在單一動作，較少在分析整個太極拳拳架的生物力學，而推手的研究更是少見。本研究主要是利用以影像為基礎的運動分析系統，量化太極拳定步推手的下肢運動學與動力學參數。為了取得肢體在運動中之三度空間軌跡，共安置三十四個反光標記於人體各肢段具有解剖意義之位置，經由攝影機擷取反光標記軌跡來替代人體之運動軌跡。使用四個測力板可分別測量下肢在運動時形成的地面反作用力，探討太極拳拳架與推手之下肢關節負荷與量化個體穩定能力的參數。本研究的目的為探討太極拳練習者在控制自身的姿勢與平衡時，下肢共存動作的協調性；並比較太極拳練習者與一般人在太極拳推手動作中，下肢在維持姿勢與平衡上的差異。評估太極拳練習者在質量中心與壓力中心的變異性，藉以分析太極拳練習者如何在推手時控制本身動作以及平衡的同時影響對手的平衡。結果顯示，在單獨的太極拳基本四勢動作中，臀部、膝關節與踝關節動作呈現協調且高度相關。比較太極拳練習者以及一般人的下肢運動學與動力學，太極拳練習者在推手動作具較有效的力量傳輸。地面垂直力在推手動作中佔有很重要的地位，從對手而來的向後的力道會被吸收並且轉換成向前作用力，太極拳練習者更能保持穩定性。太極拳定步雙推手動作，在對手的影響下，初學者在推手動作間轉換的困難，不是無法產生力量而是力量無法持續。資深太極拳推手者的質量中心移動是平滑勻速地進行，且能增加壓力中心與質量中心的距離，並維持姿勢與平衡。本研究進一步提供太極拳運動的鍛鍊計畫，有助於增進姿勢穩定性以及改善體能狀況。

Tai Chi Chuan (TCC) was one of the most popular exercises among senior citizens in Taiwan. Studies regarding the contribution of TCC to the improvement of physical condition have been widely performed, such as cardiopulmonary endurance, muscle strength, balance and flexibility. Biomechanical TCC studies have traditionally focused mainly on single movements, but little is known about the biomechanics of the whole set of Tai Chi movements, especially the push-hands movement characteristic. In this study, the motion capture system is used to quantify the kinematic and kinetics experiment data in lower extremity when Tai Chi activity is performed. The methodology involves motion performance analysis using retro-reflective markers. 34 retro-reflective markers are placed on selected anatomic landmarks to define the coordinate system of head, trunk, pelvis, upper arm, forearm, hand, thigh, shank and foot. Force assessment uses four floor-mounted force plates. Ground reaction force is primarily calculated with the utilization of a floor- mounted two tri-axial force plate. The scientific aims of the proposed research project are: 1) To observe the coordination when coexisting motion among the hip, knee and ankle joints of front and rear legs is performed during a sequence of basic movements of Tai Chi Chuan; 2) To study the stable and effective force transfer between long-term Tai Chi practitioners and non-Tai Chi experience participants in Tai Chi pushing movement; 3) To analyze how the Tai Chi practitioners control his/her posture and balance while upsetting the balance of his/her opponent in push-hands by examining the COP of each foot, COM trajectories, and the distance between COP and COM between Tai Chi experts and beginners, and postural adaptation of the opponent at the instant of sudden shoving. The results showed the movement coordination among the hip, knee and ankle joints during solo performance of the Tai Chi basic movements. Motion among the hip, knee and ankle joints was coordinated and highly interrelated. Different lower-limb kinematics and kinetics were found between with and without TCC experience groups during TCC pushing movement and the TCC practitioners could generate more effective force transfer than the no TCC experience group. The vertical force plays important roles in pushing movement, and posterior force exerted from the opponent was absorbed and transformed into anterior force to help TCC practitioners remain stable. The experience differences described here indicate that TCC beginner may have certain difficulties with movement transfers, not because of any inability to generate the forces required but because of disruptions in the temporal sequencing of the forces. TCC experts increased the distance between COP and COM to adapt themselves to their opponent’s demands without losing their root. This study will provide information and useful suggestions for training program design to improve the posture stability and improve health and give insight into the technique of TCC.

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