THE REACTION TIME OF CONTRACTION AND RELAXATION IN HUMAN SKELETAL MUSCLES / 体力科学

ABSTRACT

The purpose of this study is to investigate the reaction time of contraction and relaxation in human skeletal muscles at extremities.<BR>Reaction time of relaxation of the muscle most involved in attempting given action with and without relaxation of contralateral muscles (passive relaxation, PR, and active relaxation, AR, respectively) . Tweleve subjects, including male and female junior high student and adults, were used for the first part of the experiment.<BR>Additional subjects, four male and female adults who were engaged in relaxation training of elbow extensor muscles, were used, as the relationship between maximum tension curve of isometric exertion of elbow flexion and reaction time of relaxation in m. triceps brachii was studied.<BR>The results may be summarized as follows :<BR>1) The reaction time of muscular contraction (CR) was found to be the shortest, then AR and PR were increasingly longer in this order among male subjects, while no consistent trend in such conditions was found among females.<BR>2) No significant differences between the results of right and left legs were found in both male and females.<BR>3) The trend of reaction time diffrences in the case of arm muscles among female subjects was found to be different from the males, namely, PR, CR, and AR, respectively, PR being the shortest.<BR>4) No significant differences were found between the results of left arm reaction times under various conditions of all subjects groups, while those of right arm showed significant differences between various groups.<BR>5) AR length was shortened in two of from subjects who were engaged in 6-day long training of relaxation of triceps brachii muscles, in which no positive effort was given in contraction of elbow flexor muscles.<BR>6) When tension production curve by time was analyzed upon measuring maximum isometric strength of elbow flexor muscles in quick contraction, greater tension curve was recognized in the above mentioned two subjects whose AR was lessened.