長期練習太極拳老人跨越障礙動作控制之生物力學分析

Abstract

長期練習太極拳可提升肌力、肌耐力、柔軟度、靈活性、體適能與平衡等能力，同時可以增加身體穩定與預防跌倒的能力。本研究目的為探討太極拳對老人跨越不同高度障礙物時動作控制之影響。健康年輕人、長時間練習太極拳老人與健康老人等三組受試者被邀請至實驗室進行試驗。本研究利用動作分析系統包含七台紅外線攝影機之量測受測者跨越三種高度障礙物（10%、20% 及30％腳長）時全身之運動學資料，並利用兩塊測力板量測地面反作用力。為了提高後續動作分析的正確性，本研究新開發非侵入式且個人化的人體肢段參數之最佳化計算模型。於靜態站立測試中，太極拳組展現較好的平衡能力，而雙腳前後站立擁有較高鑑別度的測試。當擺盪腳與支撐腳越過障礙物時，太極拳組身體傾斜角有較小的前傾角與較大的後傾角。因此，太極拳組跨越障礙物採用將身體質量中心保留在較後方的策略。雖然太極拳組與另外兩組在平均關節間協調模式並無顯著差異。然而，太極拳組在支撐腳之關節協調模式與內外側全身質量中心與足底壓力中心之傾斜角等變數上有較小的變異性。跨越障礙物的多目標最佳控制模擬，太極拳組與健康年輕人有類似的跨越策略，且都不隨著障礙物高度影響。 由本研究結果顯示長期練習太極拳的受試者在跨越障礙物時，為了安全考量採取較保守的跨越模式。然而相較於健康老人，太極拳組所採取之跨越策略又較接近年輕人所使用的策略，此改變應該就是長期練習太極拳所造成的影響。

Previous studies had shown the positive effects of Tai Chi Chuan (TCC) on muscle power, flexibility, endurance, dexterity, physical fitness, and balance, which may be useful for the ability to control the body’s stability and prevention of falls. The purpose of this study was to determine the TCC effects on the movement control during obstacle-crossing. Young subjects, long-term TCC practitioners, and age-matched elderly were recruited to investigate the TCC effects on the biomechanics of obstacle crossing using motion analysis techniques. An optimization-based, non-invasive, method for estimating subject-specific body segment inertial parameters was developed. In static standing tasks, better performance was found in TCC practitioners, and the tandem standing test was a better assessment method to differentiate the balance abilities between the groups. During leading and trailing toes were above the obstacle, smaller anterior angle and greater posterior angle were observed in the TCC group, respectively. Therefore, TCC practitioners used to keep their body COM more posterior during obstacle-crossing. For the inter-joint coordination, TCC exercise did no change significantly the way the motions of the lower limb joints are coordinated during obstacle-crossing. However, TCC group decreased variability of the inter-joint coordination of the limbs during trailing limbs crossing and COM-COP inclination angle curve in the M/L. For the control strategies estimated by the multi-objective optimal control problem, TCC and young subjects performed the similar best-compromised weight sets for all obstacle conditions, which was also independent of obstacle height. In this study, it was suggested that the TCC practitioners used a more conservative strategy for obstacle-crossing due to the safety considerations. Compared to the elderly, the crossing strategies in the TCC group were more similar to those of the young subjects.