Exercise-induced sympathetic activation is correlated with cerebral hemisphere laterality, but not handedness.

To investigate whether sympathetic responses are correlated with central laterality or handedness, muscle sympathetic nerve activity (MSNA), heart rate (HR) and blood pressure (BP) were compared between right (RA) and left arm (LA) grip exercise with volitional maximum effort (MVHG) for 2 min and post-exercise arterial occlusion (PEAO) in right- and left-handed volunteers. MVHG and PEAO led to a greater increase in MSNA in RA than in LA exercise (180 vs. 150%, P=0.004; 140 vs. 85%, P=0.005). MVHG elevated HR to a significantly lesser extent in RA than in LA (35 vs. 46%, P=0.030), and the difference was maintained during PEAO. The BP rise during MVHG and PEAO was the same in RA and in LA. Muscle sympathetic nerve activity, HR and BP responses during MVHG and PEAO showed no difference between the dominant and non-dominant arm. These results suggested that the effects of central motor command and metaboreflex on sympathetic outflow to the vasculature and the heart may be selectively modulated partly by hemispherical laterality.