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Heat Acclimation Decay and Re-Induction: A Systematic Review and Meta-Analysis
Hein A M Daanen1, Sebastien Racinais2, Julien D Périard2,3
1Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, Van der Boechorststraat 7, 1081BT, Amsterdam, The Netherlands. h.a.m.daanen@vu.nl.
Heat acclimation (HA) adaptations in heart rate and core temperature decay by ~2.5% per day. Heat re-acclimation (HRA) is significantly faster than heat decay (HAD), offering a practical strategy for athletes.
Area of Science:
- Exercise Physiology
- Environmental Physiology
- Sports Science
Background:
- Heat acclimation (HA) is well-documented, but heat decay (HAD) and re-acclimation (HRA) rates are less understood.
- Understanding HAD and HRA is crucial for athletes preparing for competitions, as HA may be disruptive during tapering periods.
Purpose of the Study:
- To systematically review and meta-analyze the rates of HAD and HRA.
- To quantify the impact on heart rate (HR), core temperature (Tc), and sweat rate (SR) adaptations.
Main Methods:
- Systematic review and meta-analysis of 12 studies.
- Data retrieved from Scopus and cited references.
- Analysis of HR, Tc, and SR changes in human participants undergoing HA, HAD, and HRA.
Main Results:
- HAD resulted in a daily loss of ~2.3% in HR and ~2.6% in Tc adaptations.
- SR decay was not directly related to decay days, but longer HA periods and higher intensity improved SR adaptations.
- HRA was 8-12 times faster than HAD for HR and Tc adaptations.
Conclusions:
- HAD and HRA rates vary across physiological systems.
- HRA offers a faster and potentially less disruptive method for athletes to maintain or regain heat adaptations before competition.
- Standardization of HA and HAD protocols is needed in future research.
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