膝關節自由度限制肇使參與單位之募集與抑制

Abstract

本研究主要以Bernstein (1967) 自由度的觀點，與Newell (1986) 限制的觀點等動態系統取向，研究人體在前後平衡性動作的過程與表現中，其關節角度變化與身體各關節之間的協調與控制，檢證個體受膝關節限制及平衡練習後對其餘身體關節與自由度之募集與抑制現象。將實驗參與者32名（16男16女）分為四組，平均年齡22.2 ± 3歲，進行連續五天，每天20次，每次30秒之動態平衡儀練習，探討平衡時間、動態平衡儀碰地次數的變化。六自由度磁力追蹤儀 (Polhemus LIBERTY) 與MotionMonitor 軟體蒐集並分析個體肢段參數。使用4（組別）× 5（天）混合設計二因子變異數分析，其中天數因子為重覆量數，輔以主成分分析法進行統計考驗。隨著練習天數的增加，無論膝關節限制與否，平衡時間皆會增加，而動態平衡儀碰地次數皆會減少；動作過程方面，雙膝限制組會募集踝關節角度、凍結自由度、與減低各關節變異性以達成工作目標；前膝限制組與後膝限制組同樣募集踝關節角度以達成工作目標。經過前後平衡動作練習，（一）動作結果不受膝關節限制影響；（二）動作過程會因膝關節限制而改變；（三）動作的協調與控制會在膝關節限制情境下產生新的機制。This study applied the dynamical systems approach based on Bernstein’s (1967) degrees of freedom problem and Newell’s (1986) constraint viewpoints to investigate the influence of knee joints’ constraint in anterior-posterior balance movement and the relation between target joints. The effects of the recruitment and suppression of the degrees of freedom were examined. Thirty-two voluntarily attending participants (16 males, 16 females) were randomly assigned to 4 groups, mean age 22.2 ± 3 years old. They conducted anterior-posterior balance task for 30 seconds each time, 20 times a day, and five days successively. Their balanced time and the frequency of board-touching were measured, and the movement of the target joints were collected and recorded by the hardware of Polhemus LIBERTY and the software of MotionMonitor as well. The data were statistically analyzed by: 1) 4 (groups) ×5 (days) mixed design ANOVA with repeated measures on day factor, 2) principal components analysis (PCA). Whether knee joints constrained or not, practices could enhance the balance time and reduce the frequency of board-touching. When participants performed to meet the task requirement, three effects can be observed in the both knees constraint group during practice: 1) the increasing of ankle joint angles, 2) the decreasing of the degrees of freedom, 3) the lower joint movement variability. And there is ankle joint angles increasing in anterior and posterior knee constraint groups. Through the anterior-posterior balance task practicing, our findings were: (1) The constraint in knee joints didn’t change the consequence. (2) The constraint in knee joints could affect the movement process. (3) A new motor coordination and control emerged when knees were constrained.