The purpose of this study was to determine local sweat rate (LSR) and sweat composition during heat acclimation (HA). For ten consecutive days of HA, eight participants cycled in 33 °C and 65% relative humidity at an intensity such that a rectal temperature of 38.5 °C was reached within ~40 min, followed by a 60-min clamp of this rectal temperature (i.e., controlled hyperthermia). Four participants extended HA by a 28-day decay period and five consecutive days of heat re-acclimation (HRA) using controlled hyperthermia. Sweat from the upper arm and upper back was collected three times during each heat exposure session. LSR and sweat sodium, chloride, lactate, and potassium concentrations were determined. Relative to HA day 1, LSR was increased at the final day of HA (day 10) (arm: +58%, P < 0.001; back: +36%, P < 0.05). Concentrations of sodium, chloride, and lactate significantly (P < 0.05) decreased to ~60% at HA day 10 compared to day 1 on the arm and back. Potassium concentration did not significantly differ on HA day 10 compared to day 1 (arm: +11%, P > 0.05; back: +8%, P > 0.05). The induction patterns of the sudomotor adaptations were different. Whilst LSR increased from HA day 8 on the arm and from HA day 7 on the back, sodium and chloride conservation already occurred from HA day 3 on both skin sites. Lastly, the sweat lactate reduction occurred from HA day 6 on the arm and back. Initial evidence is provided that adaptations were partly conserved after decay (28 days) and that a 5-day HRA may be sufficient to restore HA adaptations. In conclusion, ten days of exercise-induced HA using controlled hyperthermia led to increases in LSR and concomitant reductions of sweat sodium, chloride, and lactate concentrations, whilst potassium concentrations remained relatively constant.

中文翻译：

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热适应期间的出汗率和汗液成分

本研究的目的是确定热适应 (HA) 期间的局部出汗率 (LSR) 和汗液成分。在连续 10 天的 HA 中，八名参与者在 33 °C 和 65% 的相对湿度下以一定强度骑自行车，以便在约 40 分钟内达到 38.5 °C 的直肠温度，然后对该直肠温度进行 60 分钟钳制（即，受控热疗）。四名参与者使用受控热疗将 HA 延长了 28 天的衰减期和连续五天的热再适应 (HRA)。在每次热暴露期间收集来自上臂和上背部的汗水 3 次。测定了 LSR 和汗液中钠、氯化物、乳酸盐和钾的浓度。相对于 HA 第 1 天，LSR 在 HA 的最后一天（第 10 天）增加（手臂：+58%，P < 0.001；背部：+36%，P < 0.05）。与第 1 天相比，手臂和背部的钠、氯化物和乳酸盐浓度在 HA 第 10 天显着降低（P < 0.05）至约 60%。与第 1 天相比，HA 第 10 天的钾浓度没有显着差异（手臂：+11%，P > 0.05；背部：+8%，P > 0.05）。促汗适应的诱导模式是不同的。虽然 LSR 从手臂第 8 天和背部第 7 天开始增加，但从第 3 天开始，两个皮肤部位的钠和氯保存已经发生。最后，从 HA 第 6 天开始，手臂和背部的汗液乳酸减少。初步证据表明，腐烂（28 天）后适应性部分保留，并且 5 天的 HRA 可能足以恢复 HA 适应性。综上所述，