Extraversion and the effect of exercise on spinal motoneuronal excitability

The effect of exercise on perceived arousal, as measured by the Activation-Deactivation Adjective Check List (Thayer, Psychological Reports, 42, 747–756, 1978) and on spinal motoneuronal excitability, as measured by H-reflex recovery functions, was examined for introvert and extravert groups. Exercise increased General Activation scores, with extraverts reporting greater increases in energetic arousal than introverts. Significant group differences in H-reflex recovery were limited to longer inter-pulse intervals where introverts exhibited greater motoneuronal recovery than extraverts during the pre-exercise period. Exercise diminished these differences by increasing excitability in extraverts. These results are consistent with the notion that increased dopaminergic activity contributes to processes underlying extraversion and suggest that the measurement of spinal motoneuronal excitability via H-reflex recordings may be useful in assessing these interactions.