Effects of acute exercise on the soleus H-reflex and self-reported anxiety after caffeine ingestion

The effects of moderate intensity cycling exercise on the soleus H-reflex and state anxiety were examined among 16 individuals whose anxiety was experimentally manipulated by consumption of a large dose of caffeine. The soleus H-reflex and state anxiety were measured before and 1 h after consuming caffeine or placebo and then again 10 min after 30 min of either cycling at an intensity of 60% V̇O_2peak or quiet rest. We found that (1) caffeine consumption did not influence the amplitude of the soleus H-reflex, but it did increase state anxiety; (2) acute exercise reduced the soleus H-reflex after consumption of either caffeine or placebo, but it reduced state anxiety only after consumption of caffeine; and (3) there was no evidence of a relationship between changes in the soleus H-reflex and state anxiety. Exercise-induced anxiolysis does not appear to underlie the postexercise reduction of the soleus H-reflex.