Brown HA, Topham TH, Clark B, Ioannou LG, Flouris AD, Smallcombe JW, Telford RD, Jay O, P\u00e9riard JD. Quantifying Exercise Heat Acclimatisation in Athletes and Military Personnel: A Systematic Review and Meta-analysis. Sports Med. 2024 Mar;54(3):727-741. doi: 10.1007\/s40279-023-01972-4. Epub 2023 Dec 5. PMID: 38051495.<\/p>\n
Abstract:<\/strong> Objective: The aim of this systematic review was to quantify the effects of relocating to a hotter climate to undergo heat acclimatisation in athletes and military personnel.<\/p>\n Eligibility criteria: Studies investigating the effects of heat acclimatisation in non-acclimatised athletes and military personnel via relocation to a hot climate for < 6 weeks were included.<\/p>\n Data sources: MEDLINE, SPORTDiscus, CINAHL Plus with Full Text and Scopus were searched from inception to June 2022.<\/p>\n Risk of bias: A modified version of the McMaster critical review form was utilised independently by two authors to assess the risk of bias.<\/p>\n Data synthesis: A Bayesian multi-level meta-analysis was conducted on five outcome measures, including resting core temperature and heart rate, the change in core temperature and heart rate during a heat response test and sweat rate. Wet-bulb globe temperature (WBGT), daily training duration and protocol length were used as predictor variables. Along with posterior means and 90% credible intervals (CrI), the probability of direction (Pd) was calculated.<\/p>\n Results: Eighteen articles from twelve independent studies were included. Fourteen articles (nine studies) provided data for the meta-analyses. Whilst accounting for WBGT, daily training duration and protocol length, population estimates indicated a reduction in resting core temperature and heart rate of – 0.19 \u00b0C [90% CrI: – 0.41 to 0.05, Pd = 91%] and – 6 beats\u00b7min-1 [90% CrI: – 16 to 5, Pd = 83%], respectively. Furthermore, the rise in core temperature and heart rate during a heat response test were attenuated by – 0.24 \u00b0C [90% CrI: – 0.67 to 0.20, Pd = 85%] and – 7 beats\u00b7min-1 [90% CrI: – 18 to 4, Pd = 87%]. Changes in sweat rate were conflicting (0.01 L\u00b7h-1 [90% CrI: – 0.38 to 0.40, Pd = 53%]), primarily due to two studies demonstrating a reduction in sweat rate following heat acclimatisation.<\/p>\n Conclusions: Data from athletes and military personnel relocating to a hotter climate were consistent with a reduction in resting core temperature and heart rate, in addition to an attenuated rise in core temperature and heart rate during an exercise-based heat response test. An increase in sweat rate is also attainable, with the extent of these adaptations dependent on WBGT, daily training duration and protocol length.<\/p>\n Full Text Link:<\/p>\n
\nBackground: Athletes and military personnel are often expected to compete and work in hot and\/or humid environments, where decrements in performance and an increased risk of exertional heat illness are prevalent. A physiological strategy for reducing the adverse effects of heat stress is to acclimatise to the heat.<\/p>\n