Int J Sports Med 2011; 32(11): 822-828
DOI: 10.1055/s-0031-1279767
Physiology & Biochemistry

© Georg Thieme Verlag KG Stuttgart · New York

Optimising the Acquisition and Retention of Heat Acclimation

H. A. M. Daanen1 , 2 , A. G. Jonkman1 , J. D. Layden1 , D. M. Linnane3 , A. S. Weller3
  • 1TNO Defence, Security and Safety, Department of Human Performance, Soesterberg, The Netherlands
  • 2Research Institute MOVE, Faculty of Human Movement Sciences, VU University Amsterdam, The Netherlands
  • 3Qinetiq, Human Protection and Performance Enhancement, Farnborough, United Kingdom
Further Information

Publication History

accepted after revision May 06, 2011

Publication Date:
03 November 2011 (online)

Abstract

Heat acclimation (HA) often starts in a moderately hot environment to prevent thermal overload and stops immediately prior to athletic activities. The aims of this study were 1) to establish whether acclimation to a moderately hot climate is sufficient to provide full acclimation for extreme heat and 2) to investigate the physiological responses to heat stress during the HA decay period. 15 male subjects exercised for 9 consecutive days at 26°C Wet Bulb Globe Temperature (WBGT) and 3 days at 32°C WBGT on a cycle ergometer for up to 2 h per day and repeated the exercise 3, 7 and 18 days later in 26°C WBGT. Rectal temperature (Tre) and heart rate (HR) were measured during 60 min of steady state exercise (∼ 45% of maximum oxygen uptake). During days 1–9, end-exercise Tre was reduced from 38.7±0.1 to a plateau of 38.2±0.1°C (p<0.05), HR was reduced from 156±10 to 131±11 bpm (p<0.05). No changes in HR and Tre occurred during the 3 days in the very hot environment. However, Tre during rest and exercise were significantly lower by 0.4–0.5°C after HA compared with day 9, suggesting that heat acclimation did not decay but resulted in further favourable adaptations.

References

Correspondence

Prof. Hein A. M. Daanen

TNO Defence

Security and Safety

Department of Human

Performance

Kampweg 5

3769DE Soesterberg

The Netherlands

Phone: +31/88/866 5948

Fax: +31/34/635 3977

Email: hein.daanen@tno.nl