title: Acute plasma volume expansion alters cardiovascular but not thermal function during moderate intensity prolonged exercise.
abstract: To investigate the hypothesis that the increase in plasma volume (PV) that typically occurs with training results in improved cardiovascular and thermal regulation during prolonged exercise, eight untrained males (V(O2)peak = 3.52 +/- 0.12 L x min(-1)) performed 90 min of cycle ergometry at 62% V(O2)peak before and after acute PV expansion. Subjects were infused with a PV-expanding solution (dextran (6%) or Pentaspan (10%)) equivalent to 6.7 mL x kg(-1) body mass (PVX) or acted as their own control (CON) in a randomized order. PVX resulted in a calculated 15.8% increase in resting PV, which relative to CON, was maintained throughout the exercise (P < 0.05). During PVX, heart rate was lower (P < 0.05) and stroke volume and cardiac output were higher (P < 0.05) during the exercise. Mean arterial pressure and total peripheral resistance, although altered by exercise (P < 0.05), were not different between the two conditions. Core temperature, which was progressively increased by the exercise (P < 0.01), was not affected by PVX. A similar decrease in body weight was observed between the conditions as a result of the exercise (P < 0.01). These results indicate that acute PVX alters cardiovascular performance without affecting the thermoregulatory response to prolonged cycle exercise.
authors.affiliation: Department of Kinesiology, University of Waterloo, ON, Canada.
authors.forename: B D
authors.initials: BD
authors.lastname: Roy
authors.forename: H J
authors.initials: HJ
authors.lastname: Green
authors.forename: S M
authors.initials: SM
authors.lastname: Grant
authors.forename: M A
authors.initials: MA
authors.lastname: Tarnopolsky
mesh_terms: D000328:Adult; D001831:Body Temperature; D001833:Body Temperature Regulation; D002302:Cardiac Output; D015444:Exercise; D006339:Heart Rate; D006439:Hemodynamics; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D010953:Plasma Volume; D013318:Stroke Volume