前傾および前方移動の機構を備えた座面がリーチ動作に与える影響—運動学的特徴を中心に

Effects of seat tilting and anterior movement during forward reaching movements: A kinematic characteristics analysis

要旨：座面の前傾および前方移動機構が健常成人におけるリーチ動作時の運動学的特徴に与える影響について二次元動作解析と筋電図から検討を行った．運動学的指標として，前方リーチ課題を行った際の角度変化量と筋活動を使用し，筋活動はリーチ課題の全体，前半と後半に分割し算出した．座面が後傾した後傾固定条件，前傾かつ前方移動する可動条件とした結果，体幹前傾角度と上部体幹回旋角度は可動条件の変化量が有意に小さく，リーチの前半では左外腹斜筋が，後半では左脊柱起立筋の活動が可動条件で有意に小さかった．前傾および前方移動する座面は，健常成人の身体運動を補助し，体幹の移動距離と筋力が少なくリーチ動作を行えることに寄与する可能性が示された．

　We investigated the effects of seat tilting and anterior movement during forward reaching movements in the sitting position. The subjects reached for a target placed in the forward position under 2 seat conditions: a forward-tilting and back-tilting seat that could move anteriorly. Movement was measured using kinematic analysis and muscle activities. Three time phases of muscle activities were analyzed:entire reach task time, initial reach task time, later reach task time. The trunk inclination angle and the upper trunk rotation angle in the “forward-tilting seat that moved anteriorly” were less acute than that of the seat tilted back. The left external oblique muscle activities during the first phase and the left erector spinae muscle activities during the third phase in the “forward-tilting seat that moved anteriorly” were smaller than with the seat tilted back. The “forward-tilting seat that moved anteriorly” condition may have supported body movements to reduce forward trunk inclination and trunk muscles activity during forward reaching movements.