To examine the efficacy of weekly and bi-weekly heat training to maintain heat acclimatization (HAz) and heat acclimation (HA) for 8 weeks in aerobically trained athletes.
Twenty-four males (mean [m ± standard deviation [sd]; (age, 34 ± 12 y; body mass, 72.6 ± 8.8 kg, VO2peak, 57.7 ± 6.8 mL·kg−1·min−1) completed five trials (baseline, following HAz, following HA (HAz + HA), four weeks into heat training [HTWK4], and eight weeks into HT [HTWK8] that involved 60 min of steady-state exercise (59.1 ± 1.8% vVO2peak) in an environmental laboratory (wet bulb globe temperature [WBGT], 29.6 ± 1.4 °C) on a motorized treadmill. Throughout exercise, heart rate (HR) and rectal temperature (Trec) were recorded. Following HAz + HA, participants were assigned to three groups: control group (HT0), once per week heat training (HT1), and twice per week heat training (HT2). HT involved heated exercise (WBGT, 33.3 ± 1.3 °C) to achieve hyperthermia (38.5–39.75 °C) for 60 min. Repeated measures ANOVAs were used to determine differences.
HAz + HA resulted in significant improvements in HR (p < 0.001) and Trec (p < 0.001). At HTWK8, HR was significantly higher in HT0 (174 ± 22 beats⋅min−1) compared to HT2 (151 ± 17 beats⋅min−1, p < 0.023), but was not different than HT1 (159 ± 17 beats⋅min−1, p = 0.112). There was no difference in % change of Trec from post-HAz + HA to HTWK4 (0.6 ± 1.3%; p = 0.218), however, HTWK8 (1.8 ± 1.4%) was significantly greater than post-HAz + HA in HT0 (p = 0.009).
Bi-weekly HT provided clear evidence for the ability to maintain physiological adaptions for 8 weeks following HA.
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- Extreme heat considerations in international football venues: the utility of climatologic data in decision making.J Athl Train. 2018; https://doi.org/10.4085/1062-6050-361-17
- Efficacy of heat mitigation strategies on core temperature and endurance exercise: a meta-analysis.Front Physiol. 2019; 10https://doi.org/10.3389/fphys.2019.00071
- The induction and decay of heat acclimatisation in trained athletes.Sports Med. 1991; 12: 302-312
- Adaptations and mechanisms of human heat acclimation: applications for competitive athletes and sports.Scand J Med Sci Sports. 2015; 25: 20-38https://doi.org/10.1111/sms.12408
- Heat acclimatization during summer running in the northeastern United States.Med Sci Sports Exerc. 1987; 19: 131-136
- Physiological and performance adaptations to an in-season soccer camp in the heat: associations with heart rate and heart rate variability.Scand J Med Sci Sports. 2011; 21: e477-e485https://doi.org/10.1111/j.1600-0838.2011.01378.x
- Individual responses to short-term heat acclimatisation as predictors of football performance in a hot, dry environment.Br J Sports Med. 2012; 46: 810-815https://doi.org/10.1136/bjsports-2012-091227
- Effect of heat and heat acclimatization on cycling time trial performance and pacing.Med Sci Sports Exerc. 2015; 47: 601-606https://doi.org/10.1249/MSS.0000000000000428
- Heat acclimatization of football players during initial summer practice sessions.Med Sci Sports Exerc. 2004; 36 (Supplement): S49https://doi.org/10.1249/00005768-200405001-00230
- Performance changes following heat acclimation and the factors that influence these changes: meta-analysis and meta-regression.Front Physiol. 2019; 10https://doi.org/10.3389/fphys.2019.01448
- Induction and decay of short-term heat acclimation.Eur J Appl Physiol. 2009; 107: 659https://doi.org/10.1007/s00421-009-1182-7
- Effect of permissive dehydration on induction and decay of heat acclimation, and temperate exercise performance.Front Physiol. 2016; 7https://doi.org/10.3389/fphys.2016.00564
- Heat acclimation decay and re-induction: a systematic review and meta-analysis.Sports Med. 2018; 48: 409-430https://doi.org/10.1007/s40279-017-0808-x
- Preacclimatization of men to heat by training.J Appl Physiol. 1965; 20: 379-383https://doi.org/10.1152/jappl.19184.108.40.2069
- Relations between physical training, acclimatization, and heat tolerance.J Appl Physiol. 1969; 26: 530-534https://doi.org/10.1152/jappl.19220.127.116.110
- Effect of physical conditioning on state of heat acclimatization of Bantu laborers.J Appl Physiol. 1969; 27: 262-265https://doi.org/10.1152/jappl.1918.104.22.1682
- Effects of exercise in the heat on body fluid distribution.Med Sci Sports. 1979; 11: 42-48
- Adaptive modifications in the thermoregulatory system of long-distance runners.J Appl Physiol. 1976; 40: 404-410https://doi.org/10.1152/jappl.1922.214.171.1244
- Control of sweating rate while exercising in the heat.Med Sci Sports. 1979; 11: 31-35
- Training and acclimatization: effects on responses to exercise in a desert environment.Aviat Space Environ Med. 1980; 51: 105-112
- Intermittent exercise-heat exposures and intense physical activity sustain heat acclimation adaptations.J Sci Med Sport. 2018; https://doi.org/10.1016/j.jsams.2018.06.009
- From lab to real world: heat acclimation considerations for elite athletes.Sports Med. 2017; 47: 1467-1476https://doi.org/10.1007/s40279-016-0668-9
- Application of evidence-based recommendations for heat acclimation: individual and team sport perspectives.Temperature (Austin). 2019; 6: 37-49https://doi.org/10.1080/23328940.2018.1516537
- Heat acclimation following heat acclimatization elicits additional physiological improvements in male endurance athletes.Int J Environ Res Public Health. 2021; 18: 4366https://doi.org/10.3390/ijerph18084366
- New weighting system for mean surface temperature of the human body.J Appl Physiol. 1964; 19: 531-533https://doi.org/10.1152/jappl.19126.96.36.1991
- Methods to evaluate electrolyte and water turnover of athletes.Athl Training Sports Health Care. 2009; 1: 169-179
- Assessing hydration status: the elusive gold standard.J Am Coll Nutr. 2007; 26: 575S-584S
- Global positioning system watches for estimating energy expenditure.J Strength Cond Res. 2013; 27: 3216-3220https://doi.org/10.1519/JSC.0b013e31828bae0f
- Available at)http://www.zunis.org/sports_p.htmDate accessed: March 5, 2020 (
- Modeling the wet bulb globe temperature using standard meteorological measurements.J Occup Environ Hyg. 2008; 5: 645-655https://doi.org/10.1080/15459620802310770
- A retrospective analysis to determine if exercise training-induced thermoregulatory adaptations are mediated by increased fitness or heat acclimation.Exp Physiol. 2021; 106: 282-289https://doi.org/10.1113/EP088385
- Optimising the acquisition and retention of heat acclimation.Int J Sports Med. 2011; 32: 822-828https://doi.org/10.1055/s-0031-1279767
- Role of physical fitness in heat acclimatisation, decay and reinduction.Ergonomics. 1977; 20: 399-408https://doi.org/10.1080/00140137708931642
- CORP: improving the status quo for measuring whole body sweat losses.J Appl Physiol. 2017; 123: 632-636https://doi.org/10.1152/japplphysiol.00433.2017
Published online: October 18, 2021
Accepted: October 15, 2021
Received in revised form: October 12, 2021
Received: June 29, 2021
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