Short-term isothermic heat acclimation elicits beneficial adaptations but medium-term elicits a more complete adaptation

Jodie N Moss, Freya M. Bayne, Federico Castelli, Mitchell R. Naughton, Thomas C. Reeve, Steven J. Trangmar, Richard Mackenzie, Christopher J. Tyler

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)
19 Downloads (Pure)

Abstract

Purpose: To investigate the effects of 60 min daily, short-term (STHA) and medium-term (MTHA) isothermic heat acclimation (HA) on the physiological and perceptual responses to exercise heat stress. 

Methods: Sixteen, ultra-endurance runners (female = 3) visited the laboratory on 13 occasions. A 45 min sub-maximal (40% W max) cycling heat stress test (HST) was completed in the heat (40 °C, 50% relative humidity) on the first (HST PRE), seventh (HST STHA) and thirteenth (HST MTHA) visit. Participants completed 5 consecutive days of a 60 min isothermic HA protocol (target T re 38.5 °C) between HST PRE and HST STHA and 5 more between HST STHA and HST MTHA. Heart rate (HR), rectal (T re), skin (T sk) and mean body temperature (T body), perceived exertion (RPE), thermal comfort (TC) and sensation (TS) were recorded every 5 min. During HSTs, cortisol was measured pre and post and expired air was collected at 15, 30 and 45 min. 

Results: At rest, T re and T body were lower in HST STHA and HST MTHA compared to HST PRE, but resting HR was not different between trials. Mean exercising T re, T sk, T body, and HR were lower in both HST STHA and HST MTHA compared to HST PRE. There were no differences between HST STHA and HST MTHA. Perceptual measurements were lowered by HA and further reduced during HST MTHA

Conclusion: A 60 min a day isothermic STHA was successful at reducing physiological and perceptual strain experienced when exercising in the heat; however, MTHA offered a more complete adaptation.

Original languageEnglish
Pages (from-to)243-254
Number of pages12
JournalEuropean Journal of Applied Physiology
Volume120
Early online date25 Nov 2019
DOIs
Publication statusPublished - Jan 2020
Externally publishedYes

Bibliographical note

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Keywords

  • Heat strain
  • Acclimatisation
  • Endurance performance
  • Taper
  • Thermoregulation

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health
  • Physiology (medical)
  • Orthopedics and Sports Medicine

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