人体筋の力・速度関係に及ぼす短縮前状態の影響

抄録

The force-velocity relationships were determined on six adult males by two methods providing different previous states of shortening; the maximum elbow flexions were made against a gived load from (a) the state of isometric contraction (quick release method: QR) and from (b) the resting state (after load method: AL). The apparatus used was basically identical with one used by Wilkie (1950). The loads were prescribed by the fractiens (%) of isometric tension (P_o) of the individual. The velocity was measured using a linear velocity transducer. The results obtained were as follows; 1)The velocities under the loads above 10%P_o were unexceptionally greater in AL when compared them intra-individually. On the contrary the maximum velocities with no weight were greater in QR with the exception of two subjects. Thus, the force-velocity relationship in QR was more concave than that in AL; a/P_o values in the mean were 0.43 and 0.26 for AL and QR, respectively. 2)The maximum mechanical power in QR was about 25% less than that in AL. 3)The amount of action potentials during shortening, which was obtained by integrating the EMG of brachial biceps muscle with surface electrodes, did not show any considerable differences between QR and AL methods. 4)The initial accelerations, from the onset to peak velocity, were always greater in QR due to less time occupied to reach its peak velocity. 5)Taking these results and references into consideration, it was discussed that the greater velocity in AL might be in part due to an delayed recoil of elastic energy stored at an early stage of shortening, as in a whip.