Blood flow to skeletal muscle increases during exercise. The vasodilatation of muscular blood vessels is known to be caused by metabolic products released during exercise. However, a role of sympathetic neural control of muscle circulation during exercise is controversial. We hypothesized that the response in muscle sympathetic nerve activity may initiate muscle vasodilatation preceding metabolic hyperemia during exercise. To solve this question, the effects of mental simulation of previously-performed handgrip exercise on muscle blood flow and vascular conductance were examined using ultrasonic Doppler flowmetry in humans. Heart rate increased during mental simulation of exercise in the same time course and magnitude as those during the actual handgrip exercise. Mean arterial blood pressure did not change significantly during mental exercise whereas it decreased initially and increased during the actual exercise. Both brachial blood flow and vascular conductance increased approximately 30% during mental simulation of exercise. The present results suggest that descending central command from the higher brain center induces neurogenic vasodilatation of skeletal muscle blood vessels through the muscle sympathetic nerve.

DESCENTE SPORTS SCIENCE Vol.23/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE