Quantitative EMG analysis of anticipatory postural adjustments of voluntary contraction of leg muscles in standing man.

The present experiment was undertaken to investigate the sequence of postural muscle activities involved in rapidly standing on the toes from a variety of standing positions. By varying the angle of incline of the platform on which the subject was standing, it was possible to study changes in the adaptability of the anticipatory postural muscle activity. Results showed that the initial inclination of the platform had a significant effect on the duration of soleus muscle activity and the onset and duration of tibialis anterior muscle activity. It appears that preparatory and focal motor activity can be modulated in an adaptive way according to the change in movement mechanics resulting from standing on an inclined platform.