Sports Health. 2022 Sep-Oct;14(5):694-701. doi: 10.1177/19417381211050643. Epub 2021 Oct 27.
The purpose of this study was to investigate effects of heat acclimatization (HAz) followed by heat acclimation (HA), and intermittent heat training (IHT) on time-trial performance.
Time-trial performance will improve after HA and will further improve with twice a week of IHT.
Interventional study.
Level 3.
A total of 26 male athletes (mean ± SD; age, 35 ± 12 years; body mass, 72.8 ± 8.9 kg; peak oxygen consumption [VO], 57.3 ± 6.7 mL·kg·min) completed five 4-km time trials (baseline, post-HAz, post-HA, post-IHT4, post-IHT8) in the heat (ambient temperature, 35.4°C ± 0.3°C; relative humidity, 46.7% ± 1.2%) on a motorized treadmill. After baseline time trial, participants performed HAz (109 ± 10 days) followed by post-HAz time trial. Then, participants completed 5 days of HA, which involved exercising to induce hyperthermia (38.50°C-39.75°C) for 60 minutes. Participants were then divided into 3 groups and completed IHT either twice per week (IHT), once per week (IHT), or not at all (IHT) over an 8-week period. The exercise used for the IHT matched the HA. Four-kilometer time trials were performed after 4 weeks (post-IHT4) and 8 weeks of IHT (post-IHT8).
Time trial was faster in post-HA (17.98 ± 2.51 minutes) compared with baseline (18.61 ± 3.06 minutes; = 0.037) and post-HAz (18.66 ± 3.12 minutes; = 0.023). Percentage change in time trial was faster in IHT (-3.9% ± 5.2%) compared with IHT (11.5% ± 16.9%) ( = 0.020) and approached statistical significance with large effect (effect size = 0.96) compared with IHT (1.6% ± 6.2%; = 0.059) at post-IHT8. Additionally, IHT (-2.2% ± 4.2%) was faster than IHT (3.6% ± 6.9%) ( = 0.05) at post-IHT4.
These results indicate that HA after HAz induces additional improvement in time-trial performance. IHT twice per week shows improvement after 8 weeks, while once per week maintains performance for 8 weeks. No IHT results in a loss of adaptations after 4 weeks and even greater losses after 8 weeks.
HA after HAz improves time-trial performance, twice a week of IHT improves performance further, and once a week of IHT maintains performance for at least 8 weeks.
本研究旨在探究热适应（HAz）后进行热适应（HA）和间歇性热训练（IHT）对计时赛表现的影响。
HA 后计时赛表现会提高，且每周进行两次 IHT 会进一步提高。
干预研究。
3 级。
共有 26 名男性运动员（平均±标准差；年龄，35±12 岁；体重，72.8±8.9kg；峰值摄氧量[VO]，57.3±6.7mL·kg·min）在热环境（环境温度 35.4°C±0.3°C；相对湿度 46.7%±1.2%）下使用电动跑步机完成了 5 次 4km 计时赛（基础、HAz 后、HA 后、IHT4 后、IHT8 后）。在基础计时赛后，参与者进行了 HAz（109±10 天），随后进行了 HAz 后计时赛。然后，参与者完成了 5 天的 HA，包括运动以诱导体温升高（38.50°C-39.75°C）60 分钟。然后，参与者被分为 3 组，在 8 周内每周进行 2 次（IHT）、1 次（IHT）或不进行 IHT。IHT 使用的运动与 HA 相匹配。4 周后（IHT4 后）和 8 周 IHT 后（IHT8 后）进行 4km 计时赛。
与基础（18.61±3.06 分钟； = 0.037）和 HAz 后（18.66±3.12 分钟； = 0.023）相比，HA 后计时赛更快（17.98±2.51 分钟； = 0.037）。与 IHT（11.5%±16.9%； = 0.020）相比，IHT（-3.9%±5.2%）的计时赛百分比变化更快，且与 IHT（1.6%±6.2%； = 0.059）相比具有统计学意义（效应量=0.96），且在 IHT8 后接近统计学意义。此外，与 IHT（3.6%±6.9%）相比，IHT（-2.2%±4.2%）在 IHT4 后更快（ = 0.05）。
这些结果表明，HAz 后的 HA 可进一步提高计时赛表现。每周进行 2 次 IHT 可在 8 周后提高表现，而每周 1 次 IHT 至少 8 周可保持表现。不进行 IHT 在 4 周后会导致适应性丧失，8 周后甚至更大。
HAz 后的 HA 可提高计时赛表现，每周 2 次的 IHT 可进一步提高表现，每周 1 次的 IHT 至少可维持 8 周的表现。
