ISSN:
1439-6327
Keywords:
Dynamic exercise
;
Cerebral blood flow
;
Flow resistance
;
Resistance index
;
Pulsatility index
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Cerebral blood volume flow and flow velocity have been reported to increase during dynamic exercise, but whether the two increase in parallel and whether both increases occur as functions of exercise intensity remain unsettled. In this study, blood flow velocity in the common carotid artery was measured using the Doppler ultrasound method in eight healthy male students during graded treadmill exercise. The exercise consisted of stepwise progressive increases and decreases in exercise intensity. The peak intensity corresponded to approximately 85% of maximal oxygen consumption. During this exercise, the heart rate (f c), mean blood pressure (BP) in the brachial artery and mean blood flow velocity (νcc) in the common carotid artery increased as functions of exercise intensity. At the peak exercise intensity, (f c), BP and νcc increased by 134.5%, 20.5% and 51.8% over the control levels before exercise (P 〈 0.01), respectively. The resistance index (RI) and pulsatility index (PI) were determined from the velocity profile and were expected to reflect the distal cerebral blood flow resistance. The RI and PI increased during the graded exercise, but tended to decrease at the highest levels of exercise intensity. As νcc increased with increases in exercise intensity it would be expected that cerebral blood flow would also increase at these higher intensities. It is also suggested that blood flow velocity in the cerebral artery does not proportionately reflect the cerebral blood flow during dynamic exercise, since the cerebral blood flow resistance changes.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00238569
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