Effect of acute plasma volume expansion on thermoregulation and exercise performance in the heat.
OBJECTIVE
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 (VO2peak) 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 degrees 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 x kg(-1) body weight of Hemaccel (35 g x L(-1) polygeline, 145 mmol x L(-1) Na+, and 145 mmol x 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 VO2 during exercise. Exercise performance was not influenced by plasma volume expansion (CON 17.5 +/- 0.4 min and PVE 17.1 +/- 0.2 min).


CONCLUSIONS
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.
Watt
M J
MJ
School of Health Sciences, Deakin University, Burwood, Australia.
Garnham
A P
AP
Febbraio
M A
MA
Hargreaves
M
M
D000064:Acclimatization / Q000502:physiology; D000328:Adult; D001642:Bicycling / Q000502:physiology; D001786:Blood Glucose / Q000378:metabolism; D001833:Body Temperature Regulation / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006358:Hot Temperature / Q000009:adverse effects; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010953:Plasma Volume / Q000502:physiology*
D001786:Blood Glucose; D019344:Lactic Acid