Temperature of Ingested Water during Exercise Does Not Affect Body Heat Storage.

• Autores: Dallon T. Lamarche, Glenn P. Kenny, Robert D. Meade, Ryan Mcginn, Martin P. Poirier, Brian J. Friesen
• Localización: Medicine & Science in Sports & exercise: Official Journal of the American College of Sports Medicine, ISSN 0195-9131, Vol. 47, Nº. 6, 2015, págs. 1272-1280
• Idioma: inglés
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• Resumen

  • AB Purpose: The objective of this study was to examine the effect of ingested water temperature on heat balance during exercise as assessed by direct calorimetry. Methods: Ten healthy males (25 +/- 4 yr) cycled at 50% V[spacing dot above]O2peak (equivalent rate of metabolic heat production (M-W) of 523 +/- 84 W) for 75 min under thermocomfortable conditions (25[degrees]C, 25% relative humidity) while consuming either hot (50[degrees]C) or cold (1.5[degrees]C) water. Four 3.2 mL[middle dot]kg-1 boluses of hot or cold water were consumed 5 min before and at 15, 30, and 45 min after the onset of exercise. Total heat loss (HL = evaporative heat loss (HE) +/- dry heat exchange (HD)) and M-W were measured by direct and indirect calorimetry, respectively. Change in body heat content ([DELTA]Hb) was calculated as the temporal summation of M-W and HL and adjusted for changes in heat transfer from the ingested fluid (Hfluid). Results: The absolute difference for HL (209 +/- 81 kJ) was similar to the absolute difference of Hfluid (204 +/- 36 kJ) between conditions (P = 0.785). Furthermore, the difference in HL was primarily explained by the corresponding changes in HE (hot: 1538 +/- 393 kJ; cold: 1358 +/- 330 kJ) because HD was found to be similar between conditions (P = 0.220). Consequently, no difference in [DELTA]Hb was observed between the hot (364 +/- 152 kJ) and cold (363 +/- 134 kJ) conditions (P = 0.971) during exercise. Conclusion: We show that ingestion of hot water elicits a greater HL relative to cold water ingestion during exercise. However, this response was only compensated for the heat of the ingested fluid as evidenced by similar [DELTA]Hb between conditions. Therefore, our findings indicate that relative to cold water ingestion, consuming hot water does not provide a thermoregulatory advantage. Both hot and cold water ingestion results in the same amount of heat stored during prolonged moderate-intensity exercise.