Effect of Ambient Temperature on Cardiovascular Drift and Maximal Oxygen Uptake
- Autores: Andrew J. Lafrenz, Jonathan E. Wingo, Matthew S. Ganio
- Localización: Medicine & Science in Sports & exercise: Official Journal of the American College of Sports Medicine, ISSN 0195-9131, Vol. 40, Nº. 6, 2008, págs. 1065-1071
- Idioma: inglés
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- Dialnet Métricas: 2 Citas
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Resumen
Purpose: This study tested the hypothesis that the magnitude of cardiovascular (CV) drift and decrease in maximal oxygen uptake (V[spacing dot above]O2max) would be greater at 35[degrees]C than at 22[degrees]C.
Methods: The increase in HR and decrease in stroke volume (SV) between 15 and 45 min of cycling at 59.2 +/- 1.9% V[spacing dot above]O2max (CV drift) was measured in hot (HEAT, 35[degrees]C) and cool (COOL, 22[degrees]C) ambient temperatures in 10 endurance-trained men (age = 23 +/- 3 yr, V[spacing dot above]O2max = 64.7 +/- 8.7 mL[middle dot]kg-1[middle dot]min-1). V[spacing dot above]O2max was measured immediately after the 45 min of cycling and again under both ambient temperature conditions on separate days after 15 min of cycling. This design permitted assessment of V[spacing dot above]O2max between the same time points that CV drift occurred. Fluid to replace sweat losses was provided during all trials.
Results: CV drift and the associated decrease in V[spacing dot above]O2max was greater (P < 0.05) in HEAT versus COOL. HR increased 11% (P < 0.05), SV decreased 11% (P < 0.05), and V[spacing dot above]O2max fell 15% (P < 0.05) between 15 and 45 min in HEAT, whereas HR and SV changed less (+2% and -2% for HR and SV, respectively, P < 0.05), and there was no significant decrease in V[spacing dot above]O2max (5%, P > 0.05) between 15 and 45 min in COOL.
Conclusion: These data demonstrate the magnitude of CV drift during prolonged submaximal exercise, and the accompanying decrease in V[spacing dot above]O2max measured immediately thereafter is greater in a hot than in a cool environment
