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Effect of acute plasma volume expansion on thermoregulation and exercise performance in the heat

WATT, MATTHEW J.; GARNHAM, ANDREW P.; FEBBRAIO, MARK A.; HARGREAVES, MARK

Medicine & Science in Sports & Exercise: May 2000 - Volume 32 - Issue 5 - p 958-962
Basic Sciences: Original Investigations

MATTHEW J. WATT, A. P. GARNHAM, M. A. FEBBRAIO, and M. HARGREAVES. Effect of acute plasma volume expansion on thermoregulation and exercise performance in the heat. Med. Sci. Sports Exerc., Vol. 32, No. 5, pp. 958–962, 2000.

Purpose We investigated the effects of acute plasma volume expansion on exercise performance in the heat.

Methods Six moderately trained men cycled for 40 min at 64 ± 2% peak pulmonary oxygen uptake (O2peak) followed by an individual performance time trial, where subjects completed a set amount of work (267 ± 15 kJ) in as little time as possible. Exercise trials were performed at 35°C with a relative humidity of 40%. Subjects performed two exercise trials: one after 13.1 ± 1% acute plasma volume expansion (PVE), which was achieved by the intravenous infusion of 8 mL·kg−1 body weight of Hemaccel® (35 g·L−1 polygeline, 145 mmol·L−1 Na+, and 145 mmol·L−1 Cl) and the other without prior treatment (CON).

Results Core temperature, skin blood flow, and heart rate progressively increased (P < 0.05) during exercise, but no differences were observed between trials. Plasma glucose and lactate were similar at rest and during exercise, as was O2 during exercise. Exercise performance was not influenced by plasma volume expansion (CON 17.5 ± 0.4 min and PVE 17.1 ± 0.2 min).

Conclusion These data suggest that, in moderately trained men, plasma volume expansion alone does not enhance thermoregulatory function and exercise performance during moderate intensity exercise in the heat.

School of Health Sciences, Deakin University, Burwood, AUSTRALIA; and Department of Physiology, The University of Melbourne, Parkville, AUSTRALIA

Submitted for publication December 1998.

Accepted for publication June 1999.

Address for correspondence: Prof. Mark Hargreaves, School of Health Sciences, Deakin University, Burwood, 3125, Australia. E-mail: mharg@deakin.edu.au.

© 2000 Lippincott Williams & Wilkins, Inc.