Acute bouts of active and passive leg cycling attenuate the amplitude of the soleus H-reflex in humans

This study compared the immediate and prolonged effects of acute bouts of active and passive leg cycling on the soleus H-reflex among 12 young healthy men. The soleus H-reflex was measured immediately before and then 10 and 30 min after 20 min of active, unloaded leg cycling, passively induced leg cycling, and quiet rest. The primary novel finding was a significant reduction in the amplitude of the soleus H-reflex 10 and 30 min after both active and passive leg cycling compared to no change after quiet rest. These results suggest that cycling exercise produces an immediate and prolonged attenuation of the H-reflex, and this attenuation is likely caused by the influence of afferent mechanoreceptors rather than by the influence of central motor command. (C) 2003 Published by Elsevier Science Ireland Ltd.