Cubel Claes, Fischer Mads, Stampe Daniel, Klaris Magnus B, Bruun Tim R, Lundby Carsten, Nordsborg Nikolai B, Nybo Lars
Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark.
Department of Health and Exercise Physiology, Inland Norway University of Applied Science, Lillehammer, Norway.
Temperature (Austin). 2024 Aug 1;11(4):350-362. doi: 10.1080/23328940.2024.2383505. eCollection 2024.
Short-term heat acclimation (HA) appears adequate for maximizing sudomotor adaptations and enhancing thermal resilience in trained athletes. However, for enhanced erythropoiesis and transfer effects to exercise capacity in cooler environments, prolonged HA appears necessary. To establish the time-course for physiological adaptations and performance effects, 20 male elite cyclists were divided into an intervention group (HEAT; = 10) completing 5 weeks of HA (six one-hour HA-training sessions per week) and control ( = 10) tested pre and post in hot (40°C) and cool conditions (20°C). HEAT completed tests at 40°C every week during HA with measures of sweat rate and [Na] and a decay test 2 weeks after termination of HA. HEAT improved time for exhaustion by 15 min ( < 0.001) in the 40°C test, increased sweat rate by 0.44 L/hour ( < 0.001), and lowered sweat sodium concentration [Na] by 14.1 mmol/L ( = 0.006) from pre- to post-HA, with performance returning to pre-HA levels in the 2-week decay test. Total hemoglobin mass (tHb) was increased by 30 grams (+3%, = 0.048) after 3 weeks and 40 grams (+4%, = 0.038) after 5 weeks in HEAT but returned to pre-HA levels at the 2-week decay test. HEAT improved incremental peak power output (+12 W, = 0.001) without significant changes in maximal oxygen uptake ( = 0.094). In conclusion, improvements in heat exercise tolerance and sudomotor adaptations materialized during the first ~3 weeks and the entire 5 weeks of HA augmented both cool exercise capacity and tHb. However, the 2-week post-HA evaluation demonstrated a rapid decay of physiological adaptations and exercise capacity in the heat.
短期热适应（HA）似乎足以使训练有素的运动员的汗腺运动适应最大化并增强热适应能力。然而，为了增强红细胞生成以及在较凉爽环境中对运动能力的转移效应，延长热适应时间似乎是必要的。为了确定生理适应和运动表现效应的时间进程，将20名男性精英自行车运动员分为干预组（热适应组；n = 10），该组完成5周的热适应（每周六次一小时的热适应训练课程），以及对照组（n = 10），在热环境（40°C）和冷环境（20°C）中进行训练前后测试。热适应组在热适应期间每周在40°C进行测试，测量出汗率和[Na]，并在热适应结束后2周进行疲劳测试。热适应组在40°C测试中疲劳时间改善了15分钟（P < 0.001），出汗率增加了0.44升/小时（P < 0.001），热适应前后汗液钠浓度[Na]降低了14.1毫摩尔/升（P = 0.006），在2周的疲劳测试中运动表现恢复到热适应前水平。热适应组在3周后总血红蛋白量（tHb）增加了30克（+3%，P = 0.048），5周后增加了40克（+4%，P = 0.038），但在2周的疲劳测试中恢复到热适应前水平。热适应组增加了递增峰值功率输出（+12瓦，P = 0.001），而最大摄氧量无显著变化（P = 0.094）。总之，在热适应的前~3周内实现了热运动耐力和汗腺运动适应的改善，整个5周的热适应增强了冷运动能力和tHb。然而，热适应后2周的评估表明，热环境下生理适应和运动能力迅速衰退。
