手指等長收縮經動作習慣化之力量變異性研究

Movement Habituation Associated with Force Variability during Finger Isometric Contraction

有關力量的控制與研究，多著重於施力輸出的快慢或變化率(rate of force)與變異性(variability)，此二者彼此存在高度的相關性。基於速度與準度不共存(speed-accuracy trade-off)之原則，在快速的力量輸出下，無形中造成變異性之急遽增加，此論點在動作控制文獻中已有具體地證實，藉由力量變化率發展之遞增模式中，已得出變異性為生物系統得以解釋有關自由度(degree-of-freedom)的關鍵因素，也就是生物系統在動作執行過程中，所能控制之自由度小於空間自由度之結果；本文透過以「習慣領域理論」(Habitual Domains Theory)之角度，證明人類行為經由反覆練習的習慣化，得以降低行為之變異性，減少行為之偏差，提高技能之穩定性。本研究方法針對29名北部某大學生進行手指等長收縮之力量控制分析，受試者以右手食指對不同力量、不同變化率及不同收縮時間進行各40次之等長收縮，以力量輸出誤差之變異性為依變項，資料分析以單因子變異數分析，就施力時期（上升、穩定、下降）、力量大小（25%及50%）與習慣化階段（學習前、學習後）進行統計分析。結果發現在施力過程有關的三個動作變數上均呈顯著效應，分別為時期F(2， 56)=169.69，P<.000。力量誤差在上升期與下降期均較穩定期來得高，三者呈一U字關係，表示力量變化過程中之控制難度較穩定力量輸出為大，但上升期與下降期力量誤差之關係並未達顯著效應。針對平均曲線之變異性上明顯發現，經過四週，每週三次的反覆練習後，施力曲線之變異性已具體下降，自施力開始直到結束，學習後之變異性均低於學習前，由本研究結論得知力量變異性隨不同施力時期而有所不同，動作習慣化對於力量控制在增加、維持與遞減上均有顯著的幫助。

Most motor control studies emphasized force production on two different aspects: 1. how fast was force produced or rate of force development， or 2. variability of force. According to speed-accuracy trade-off theory， high variability was observed during rapid force output and numerous studies had carried out in the literatures of motor control. During the decrement of force， variability associated with habitual domains were used to elaborate the bio-system in terms of degree of freedom. As a result， the variability of human behaviors were suggested to change as a function of habituation via repetitive practice to reduce errors and to enhance the stability of skill. This study analyzed force variability of finger isometric force production. 29 college studesnts were asked to produce different levels of force， rates of force development and contraction times. 40 trials were performed in each block of task. The dependent variable was the variability of force trace， the absolute mean error of force trace. Three independent variables were different significantly， timing F (2， 56)=169.69， P