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Effect of exercise on cerebral perfusion in humans at high altitude

Effect of exercise on cerebral perfusion in humans at high altitude The effects of submaximal and maximal exercise on cerebral perfusion were assessed using a portable, recumbent cycle ergometer in nine unacclimatized subjects ascending to 5,260 m. At 150 m, mean (SD) cerebral oxygenation (rS O 2 %) increased during submaximal exercise from 68.4 (SD 2.1) to 70.9 (SD 3.8) ( P < 0.0001) and at maximal oxygen uptake ( O 2 max ) to 69.8 (SD 3.1) ( P < 0.02). In contrast, at each of the high altitudes studied, rS O 2 was reduced during submaximal exercise from 66.2 (SD 2.5) to 62.6 (SD 2.1) at 3,610 m ( P < 0.0001), 63.0 (SD 2.1) to 58.9 (SD 2.1) at 4,750 m ( P < 0.0001), and 62.4 (SD 3.6) to 61.2 (SD 3.9) at 5,260 m ( P < 0.01), and at O 2 max to 61.2 (SD 3.3) at 3,610 m ( P < 0.0001), to 59.4 (SD 2.6) at 4,750 m ( P < 0.0001), and to 58.0 (SD 3.0) at 5,260 m ( P < 0.0001). Cerebrovascular resistance tended to fall during submaximal exercise ( P = not significant) and rise at O 2 max , following the changes in arterial oxygen saturation and end-tidal CO 2 . Cerebral oxygen delivery was maintained during submaximal exercise at 150 m with a nonsignificant fall at O 2 max , but at high altitude peaked at 30% of O 2 max and then fell progressively at higher levels of exercise. The fall in rS O 2 and oxygen delivery during exercise may limit exercise at altitude and is likely to contribute to the problems of acute mountain sickness and high-altitude cerebral edema. maximal oxygen uptake; cerebral oxygenation; cerebral blood flow; cerebrovascular resistance; cerebral oxygen delivery Address for reprint requests and other correspondence: C. H. E. Imray, Coventry and Warwickshire County Vascular Unit, Univ. Hospitals Coventry and Warwickshire NHS Trust, Coventry, CV2 2DX, UK (E-mail: chrisimray@aol.com ) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Applied Physiology The American Physiological Society

Effect of exercise on cerebral perfusion in humans at high altitude

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Publisher
The American Physiological Society
Copyright
Copyright © 2011 the American Physiological Society
ISSN
8750-7587
eISSN
1522-1601
DOI
10.1152/japplphysiol.00973.2004
pmid
15920097
Publisher site
See Article on Publisher Site

Abstract

The effects of submaximal and maximal exercise on cerebral perfusion were assessed using a portable, recumbent cycle ergometer in nine unacclimatized subjects ascending to 5,260 m. At 150 m, mean (SD) cerebral oxygenation (rS O 2 %) increased during submaximal exercise from 68.4 (SD 2.1) to 70.9 (SD 3.8) ( P < 0.0001) and at maximal oxygen uptake ( O 2 max ) to 69.8 (SD 3.1) ( P < 0.02). In contrast, at each of the high altitudes studied, rS O 2 was reduced during submaximal exercise from 66.2 (SD 2.5) to 62.6 (SD 2.1) at 3,610 m ( P < 0.0001), 63.0 (SD 2.1) to 58.9 (SD 2.1) at 4,750 m ( P < 0.0001), and 62.4 (SD 3.6) to 61.2 (SD 3.9) at 5,260 m ( P < 0.01), and at O 2 max to 61.2 (SD 3.3) at 3,610 m ( P < 0.0001), to 59.4 (SD 2.6) at 4,750 m ( P < 0.0001), and to 58.0 (SD 3.0) at 5,260 m ( P < 0.0001). Cerebrovascular resistance tended to fall during submaximal exercise ( P = not significant) and rise at O 2 max , following the changes in arterial oxygen saturation and end-tidal CO 2 . Cerebral oxygen delivery was maintained during submaximal exercise at 150 m with a nonsignificant fall at O 2 max , but at high altitude peaked at 30% of O 2 max and then fell progressively at higher levels of exercise. The fall in rS O 2 and oxygen delivery during exercise may limit exercise at altitude and is likely to contribute to the problems of acute mountain sickness and high-altitude cerebral edema. maximal oxygen uptake; cerebral oxygenation; cerebral blood flow; cerebrovascular resistance; cerebral oxygen delivery Address for reprint requests and other correspondence: C. H. E. Imray, Coventry and Warwickshire County Vascular Unit, Univ. Hospitals Coventry and Warwickshire NHS Trust, Coventry, CV2 2DX, UK (E-mail: chrisimray@aol.com )

Journal

Journal of Applied Physiology – The American Physiological Society

Published: Aug 1, 2005

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