Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, CANADA.
Med Sci Sports Exerc. 2015 Jun;47(6):1272-80. doi: 10.1249/MSS.0000000000000533.
The objective of this study was to examine the effect of ingested water temperature on heat balance during exercise as assessed by direct calorimetry.
Ten healthy males (25 ± 4 yr) cycled at 50% V˙O2peak (equivalent rate of metabolic heat production (M-W) of 523 ± 84 W) for 75 min under thermocomfortable conditions (25°C, 25% relative humidity) while consuming either hot (50°C) or cold (1.5°C) water. Four 3.2 mL·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 (ΔHb) was calculated as the temporal summation of M-W and HL and adjusted for changes in heat transfer from the ingested fluid (Hfluid).
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 ΔHb was observed between the hot (364 ± 152 kJ) and cold (363 ± 134 kJ) conditions (P = 0.971) during exercise.
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 ΔHb 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.
本研究旨在通过直接量热法评估摄入水温度对运动时热量平衡的影响。
10 名健康男性（25±4 岁）在热舒适条件下（25°C，25%相对湿度）以 50%峰值摄氧量（代谢产热（M-W）的等效率为 523±84 W）进行 75 分钟的自行车运动，同时摄入热水（50°C）或冷水（1.5°C）。在运动开始前 5 分钟以及运动后 15、30 和 45 分钟时，分别摄入 4 次 3.2 毫升·千克⁻¹的热水或冷水。通过直接和间接量热法分别测量总热损失（HL=蒸发热损失（HE）±干热交换（HD））和 M-W。通过 M-W 和 HL 的时间总和计算体热含量（ΔHb），并对摄入液体引起的热传递（Hfluid）的变化进行调整。
HL 的绝对值差异（209±81 kJ）与条件之间的 Hfluid 的绝对值差异（204±36 kJ）相似（P=0.785）。此外，HL 的差异主要由相应的 HE 变化引起（热水：1538±393 kJ；冷水：1358±330 kJ），因为 HD 在条件之间相似（P=0.220）。因此，在运动期间，热水（364±152 kJ）和冷水（363±134 kJ）条件下没有观察到ΔHb 的差异（P=0.971）。
我们表明，与摄入冷水相比，摄入热水会在运动期间引起更大的 HL。然而，这一反应仅通过条件之间相似的ΔHb 来补偿摄入液体的热量。因此，我们的研究结果表明，与摄入冷水相比，摄入热水并没有提供热调节优势。在长时间的中等强度运动中，摄入热水和冷水都会导致相同量的热量储存。
