During heel raising from standing position, the EMG reaction time (EMG-RT) can be devided into two phases, the cognitive factor (LT) and the postural response (DUR), because of the anticipatory EMG activity in the Tibialis anterior (TA) appeared prior to the onset of the EMG activity in the agonist (LG). The aim of this study was to examine the developmental changes of the LT, the DUR, and the ratio of the LT (%LT) and the DUR (%DUR) to the EMG-RT, in the training of normal adults (aged 21 and 23 years) and with advance of the age in normal children (aged between 8 and 15years).
In the training of the adults, The DUR shortened but the LT did not change with shortening of the EMG-RT. With advance of the age in the children, however, the LT shortened but the DUR did not change with the shortening of the EMG-RT. Then, the %LT in the children was larger than that of the adults, while the %DUR was smaller than that of the adults. Thease results suggest that the manner of the develpmental changes of the LT (cognitive factor) and the DUR (postural response) with the shortening of the EMG-RT was different between the traing in the adult and with advance of the age in the children during heel raise from standing position.