The purpose of this study was to examine the effect of heat acclimation (HA) on thirst levels, sweat rate, and percentage of body mass loss (%BML), and changes in fluid intake factors throughout HA induction. Twenty-eight male endurance athletes (mean ± SD; age, 35 ± 12 years; body mass, 73.0 ± 8.9 kg; maximal oxygen consumption, 57.4 ± 6.8 ml·kg⁻¹·min⁻¹) completed 60 min of exercise in a euhydrated state at 58.9 ± 2.3% velocity of maximal oxygen consumption in the heat (ambient temperature, 35.0 ± 1.3 °C; relative humidity, 48.0 ± 1.3%) prior to and following HA where thirst levels, sweat rate, and %BML were measured. Then, participants performed 5 days of HA while held at hyperthermia (38.50–39.75 °C) for 60 min with fluid provided ad libitum. Sweat volume, %BML, thirst levels, and fluid intake were measured for each session. Thirst levels were significantly lower following HA (pre, 4 ± 1; post, 3 ± 1, p < .001). Sweat rate (pre, 1.76 ± 0.42 L/hr; post, 2.00 ± 0.60 L/hr, p = .039) and %BML (pre, 2.66 ± 0.53%; post, 2.98 ± 0.83%, p = .049) were significantly greater following HA. During HA, thirst levels decreased (Day 1, 4 ± 1; Day 2, 3 ± 2; Day 3, 3 ± 2; Day 4, 3 ± 1; Day 5, 3 ± 1; p < .001). However, sweat volume (Day 1, 2.34 ± 0.67 L; Day 2, 2.49 ± 0.58 L; Day 3, 2.67 ± 0.63 L; Day 4, 2.74 ± 0.61 L; Day 5, 2.74 ± 0.91 L; p = .010) and fluid intake (Day 1, 1.20 ± 0.45 L; Day 2, 1.52 ± 0.58 L; Day 3, 1.69 ± 0.63 L; Day 4, 1.65 ± 0.58 L; Day 5, 1.74 ± 0.51 L; p < .001) increased. In conclusion, thirst levels were lower following HA even though sweat rate and %BML were higher. Thirst levels decreased while sweat volume and fluid intake increased during HA induction. Thus, HA should be one of the factors to consider when planning hydration strategies.

本研究的目的是检查热适应 (HA) 对口渴水平、出汗率和体重减轻百分比 (%BML) 的影响，以及整个 HA 诱导过程中液体摄入因素的变化。28 名男性耐力运动员（平均值 ±  SD；年龄，35 ± 12 岁；体重，73.0 ± 8.9 kg；最大耗氧量，57.4 ± 6.8 ml·kg ^-1 ·min ^-1) 在 HA 之前和之后在口渴水平的情况下，以 58.9 ± 2.3% 的热量（环境温度，35.0 ± 1.3 °C；相对湿度，48.0 ± 1.3%）的最大耗氧速度完成 60 分钟的水合状态运动，测量出汗率和％BML。然后，参与者在热疗（38.50-39.75°C）下进行 5 天的 HA，同时保持 60 分钟，并随意提供液体。测量每个疗程的出汗量、%BML、口渴程度和液体摄入量。HA 后口渴水平显着降低（前，4 ± 1；后，3 ± 1，p  < .001）。出汗率 (pre, 1.76 ± 0.42 L/hr; post, 2.00 ± 0.60 L/hr, p  = .039) 和 %BML (pre, 2.66 ± 0.53%; post, 2.98 ± 0.83%, p = .049）在 HA 后显着增加。在 HA 期间，口渴水平降低（第 1 天，4 ± 1；第 2 天，3 ± 2；第 3 天，3 ± 2；第 4 天，3 ± 1；第 5 天，3 ± 1；p  < .001）。然而，汗液量（第 1 天，2.34 ± 0.67 L；第 2 天，2.49 ± 0.58 L；第 3 天，2.67 ± 0.63 L；第 4 天，2.74 ± 0.61 L；第 5 天，2.74 ± 0.91 L；p  = .010）和液体摄入量（第 1 天，1.20 ± 0.45 L；第 2 天，1.52 ± 0.58 L；第 3 天，1.69 ± 0.63 L；第 4 天，1.65 ± 0.58 L；第 5 天，1.74 ± 0.51 L；p  < .001）增加. 总之，即使出汗率和 %BML 较高，HA 后的口渴水平也较低。在 HA 诱导期间，口渴水平下降，而汗液量和液体摄入量增加。因此，HA 应该是规划补水策略时要考虑的因素之一。