Effect of microgravity on the electromyographic activity of two upperlimb muscles during a goal-directed movement and during locomotion.

It is well known that both neuromuscular and perceptual properties are affected during spaceflight. These modificaitons can therefore induce dramatic alterations in the mechanical basis of movements and locomotion disturbances. The main objectives of this study were: 1) to examine whether the nervous control of muscular activity in the upper limbs of the rhesus monkey (Macaca mulatta) was modified in a microgravity environment; and 2) to quantify the electromyographic (EMG) pattern of biceps (BI) and triceps (TRI) muscles pre-, in-, and postflight during performance of goal-directed movements and locomotion.