European Journal of Applied Physiology

, Volume 104, Issue 2, pp 321–327 | Cite as

Lowering of resting core temperature during acclimation is influenced by exercise stimulus

  • Bernhard Kampmann
  • Peter Bröde
  • Martin Schütte
  • Barbara Griefahn
Original Article

Abstract

The decrease in resting core temperature (Tco) and its relation to the reduced physiological strain during heat acclimation was analysed with rectal temperature data measured in three groups of eight semi-nude persons (6 males, 2 females) who were acclimated for 15 consecutive days to dry, humid and radiant heat, respectively, with equivalent WBGT (33.5°C), by performing 2-h treadmill work. A fourth group followed the same protocol for 12 days in a neutral climate. After acclimation, both resting Tco, prior to heat exposure, and final Tco, measured at the end of work, were significantly reduced. The reduction in final Tco increased with decreasing ambient water vapour pressure and was higher for the data pooled over the heat conditions (0.46 ± 0.31°C) than in the neutral climate (0.21 ± 0.25°C), whereas resting Tco declined similarly in the heat (0.20 ± 0.25°C) and the neutral environment (0.17 ± 0.23°C). The lowering of resting and final Tco after heat acclimation showed a significant correlation (r = 0.67) and regression analysis showed that 37% of the average reduction in final Tco was attributable to the lowering of resting Tco. The same analysis was applied after extending the database by short-term series of clothed persons (17 females, 16 males) acclimated at 29.5 and 31.5°C WBGT for 5 days. A significant correlation was found between the lowering of resting and final Tco (r = 0.57) that did not depend on climatic conditions and gender, although the reduction in resting Tco was significantly smaller for females (0.06 ± 0.22°C) than for males (0.21 ± 0.23°C). It is concluded that the lowering of resting core temperature contributes to the reduced physiological strain during heat acclimation. Similar effects under neutral conditions point to the exercise stimulus as a probable explanation.

Keywords

Acclimation Heat stress Exercise Resting core temperature Rectal temperature Gender 

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Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Bernhard Kampmann
    • 1
  • Peter Bröde
    • 2
  • Martin Schütte
    • 2
  • Barbara Griefahn
    • 2
  1. 1.Division of Applied Physiology, Occupational Medicine and Infectiology, Department of Safety EngineeringBergische Universität WuppertalWuppertalGermany
  2. 2.Leibniz Research Centre for Working Environment and Human Factors at the University of Dortmund (IfADo)DortmundGermany

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