School of Sport Sciences, UiT The Arctic University of Norway, Tromsø, Norway.
School of Exercise and Nutrition Sciences, Queensland University of Technology (QUT), Brisbane, Australia.
Eur J Appl Physiol. 2021 Oct;121(10):2761-2772. doi: 10.1007/s00421-021-04744-y. Epub 2021 Jun 19.
This study investigated the effect of 5 days of heat acclimation training on neuromuscular function, intestinal damage, and 20 km cycling (20TT) performance in the heat.
Eight recreationally trained males completed two 5-day training blocks (cycling 60 min day at 50% peak power output) in a counter-balanced, cross-over design, with a 20TT completed before and after each block. Training was conducted in hot (HA: 34.9 ± 0.7 °C, 53 ± 4% relative humidity) or temperate (CON: 22.2 ± 2.6 °C, 65 ± 8% relative humidity) environment. All 20TTs were completed in the heat (35.1 ± 0.5 °C, 51 ± 4% relative humidity). Neuromuscular assessment of knee extensors (5 × 5 s maximum voluntary contraction; MVC) was completed before and after each 20TT and on the first and last days of each training block.
MVC torque was statistically higher after 5 days of HA training compared to CON (mean difference = 14 N m [95% confidence interval; 6, 23]; p < 0.001; d = 0.77). However, 20TT performance after 5 days of HA training was not statistically different to CON, with a between-conditions mean difference in the completion time of 68 s [95% confidence interval; - 9, 145] (p = 0.076; d = 0.35).
Short-term heat acclimation training may increase knee extensor strength without changes in central fatigue or intestinal damage. Nevertheless, it is insufficient to improve 20 km self-paced cycling performance in the heat compared to workload-matched training in a temperate environment. These data suggest that recreationally trained athletes gain no worthwhile performance advantage from short-term heat-training before competing in the heat.
本研究旨在探讨 5 天热适应训练对热环境下神经肌肉功能、肠道损伤和 20km 骑行（20TT）表现的影响。
8 名有经验的男性运动员以交叉平衡、对照设计的方式完成了两个为期 5 天的训练模块（在 50%峰值功率输出下每天骑行 60 分钟），每个模块前后都完成了 20TT。训练在炎热（HA：34.9±0.7°C，53±4%相对湿度）或温和（CON：22.2±2.6°C，65±8%相对湿度）环境中进行。所有 20TT 均在热环境（35.1±0.5°C，51±4%相对湿度）中完成。在每个 20TT 前后以及每个训练模块的第一天和最后一天，对膝关节伸肌（5×5s 最大自主收缩；MVC）的神经肌肉评估完成。
与 CON 相比，5 天 HA 训练后 MVC 扭矩明显更高（平均差异=14N m [95%置信区间；6，23]；p<0.001；d=0.77）。然而，5 天 HA 训练后 20TT 表现与 CON 无统计学差异，完成时间的条件间平均差异为 68s [95%置信区间；-9，145]（p=0.076；d=0.35）。
短期热适应训练可能会增加膝关节伸肌力量，而不会改变中枢疲劳或肠道损伤。然而，与在温和环境中进行匹配工作量的训练相比，它不足以提高热环境下 20km 自我计时骑行的表现。这些数据表明，对于在热环境中比赛的业余运动员来说，在比赛前进行短期热训练不会带来有价值的表现优势。
