ABSTRACT

　 We examined central arterial and cerebral hemodynamics during intermittent highintensity exercise. In addition, the response of the pulsatile buffering function in the arterial system from the aorta to the cerebral vessels was also evaluated. Twelve healthy young adults （age 24±2 years） underwent an intermittent high-intensity cycling exercise test consisting of four alternating sessions of 3 minutes of exercise at 50-60% maximal workload （moderate-intensity） and 4 minutes of exercise at 80-90% of maximal workload（high-intensity） . Throughout the exercise protocol, brachial arterial pressure waveforms were invasively recorded for estimation of systemic hemodynamic variables including stroke volume, cardiac output （CO） , and total peripheral resistance （TPR） （via Modelflow method） . In addition, aortic blood pressure was computed from brachial arterial pressure waveforms （via general transfer function technique）. Moddle cerebral arterial blood flow velocity（CBFV） was measured by trans cranial Doppler method. Cerebrovascular admittance was evaluated by transfer function method. The total peripheral vascular resistance （=mean arterial pressure/ CO） decreased gradually after the start of exercise, and exhibited edging lower after the third moderate-intensity exercise. In contrast, the cerebral vascular resistance index （=mean arterial pressure/mean CBFV） and admittance did not change significantly during the exercise. These results indicate that although systemic vasodilation occurs during intermittent high-intensity exercise, vasodilation is less likely to occur in the cerebral vascular bed. The cerebral vascular bed may maintain vascular tonus against the excessive cerebral perfusion associated with transient high-intensity exercise as a defens mechanism against the mechanical stress of pulsatile fluctuation.

DECENTE SPORTS SCIENCE Vol.43/The DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE