Abstract
Summary
Changes in cerebral blood flow (C.B.F.) induced by acute exercise (5 minutes of Harvard Step Test at 20/min) were recorded with the aid of an impedance rheograph in 11 subjects (4 males and 7 females) with various degrees of physical training (2 females completely untrained). Flow pulses and their electronic integration were recorded before and after the period of exercise. A substantial increase in the height of the cerebral flow pulses, (males + 27%; females + 49%) and an even larger increase in the integrated recordings, (males + 68%; females + 92%), were observed in all subjects. The increase in C.B.F. lasted for more than 5 minutes after the end of the exercise. A marked increase in heart rate (+42 b/min for males and +61 b/min for females) and a small initial decrease in skin temperature followed 2 min later by an increase were observed also. Changes in heart rate were highly significant but changes in skin temperature were not. The similarity of these responses to those elicited by hypoxia and the possibility of a participation of the chemoreceptors in the cardiovascular and respiratory reactions observed during exercise were noted.
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