Somatosensory graviception inhibits the soleus H-reflexin standing man - an underwater experiment-

H-reflexes were elicited in the soleus muscle in subjects standing on a force platform in a water tank, under different loading conditions at the ankle joint. The joint loading was altered by changing the combination of buoys and weights attached to lower limb segments, while the total body mass was kept the same. The results revealed that as the joint load was reduced the H-reflex was significantly enhanced as compared to that under the control condition, while it decreased as the joint load was increased, despite the same background EMG activity level. It was demonstrated that the augmented load information from the lower limb joints has an inhibitory effect on the soleus H-reflex, suggesting that this might be one of underlying neural mechanisms responsible for the suppression of H-reflex during human upright standing.