European Journal of Applied Physiology

, Volume 114, Issue 11, pp 2399–2410 | Cite as

Do greater rates of body heat storage precede the accelerated reduction of self-paced exercise intensity in the heat?

  • Nicholas M. Ravanelli
  • Matthew N. Cramer
  • Yannick Molgat-Seon
  • Anthony N. Carlsen
  • Ollie Jay
Original Article



To reevaluate the previous hypothesis that greater reductions in self-paced exercise intensity in the heat are mediated by early differences in the rate of body heat storage (S).


Eight trained volunteers cycled in 19 °C/1.8 kPa (COOL), 25 °C/1.2 kPa (NORM), and 34 °C/1.6 kPa (HOT), while maintaining an RPE of 16. Potential differences in S following the onset of exercise were assessed by comparing rates of esophageal temperature change (ΔT est); and estimated S values using a traditional two-compartment thermometric model (S therm) of changes in rectal (T re) and skin (T sk) temperature, and partitional calorimetry (S cal).


After 15 min of exercise, workload decreased more in HOT vs. COOL (P = 0.03), resulting in a shorter time (HOT: 40.7 ± 14.9 min; COOL: 53.5 ± 18.7 min; P = 0.04) to 70 % of initial workload. However, there were no preceding differences in ΔT est between conditions (P = 0.18). S therm values were different between HOT and COOL during the first 5 min of exercise (P < 0.05), primarily due to negative S therm values (−32 ± 15 kJ min−1) in COOL, which according to partitional calorimetric measurements, required improbably high (~56 kJ min−1) rates of evaporation when no sweating on the back and thigh was observed until after 7.6 ± 1.5 min and 4.8 ± 1.7 min of exercise, respectively. S cal values in the first 5 min of exercise confirmed S was actually positive in COOL (+21 ± 8 kJ min−1) and not negative. Different S therm values following the onset of exercise at different environmental temperatures are simply due to transient differences in the rate of change in T sk.


Reductions in self-paced exercise intensity in the heat are not mediated by early differences in S following the onset of exercise.


Core temperature Exercise performance Partitional calorimetry Rating of perceived exertion Thermoregulation 



Effective radiant surface area (ND)


Biceps femoris


Body surface area (m2)


Convective heat exchange (W m−2)


Convective heat exchange via respiration (W m−2)


Evaporative heat loss from the skin (W m−2)


Evaporative heat loss via respiration (W m−2)


Caloric equivalent of carbohydrates (kJ LO−2)


Caloric equivalent of lipids (kJ LO−2)


Electromyography (% of initial EMG)


Area-weighted emissivity of the skin (ND)


Area-weighted clothing factor (ND)


Gluteus maximus


Combined heat transfer coefficient (W m−2 °C−1)


Convective heat transfer coefficient (W m−2 °C−1)


Radiative heat transfer coefficient (W m−2 °C−1)


Rate of metabolic heat production (W m−2)


Integrated electromyography (% of initial iEMG)


Lateral gastrocnemius


Local sweat rate on the lower back (mg cm−2 min−1)


Local sweat rate on the thigh (mg cm−2 min−1)


Metabolic energy expenditure (W m−2)


Physical Activity Readiness Questionnaire


Ambient water vapor pressure (kPa)


Radiant Heat exchange (W m−2)


Thermal resistance of clothing (m2 °C W−1)


Respiratory exchange ratio (ND)


Rating of perceived exertion


Rate of body heat storage (kJ min−1)


Rate of body heat storage measured with partitional calorimetry (kJ min−1)


Rate of body heat storage estimated with a traditional 2-compartment thermometry model (kJ min−1)


Stefan-Boltzmann constant (5.67 × 10−8W m−2 °C−4)


Ambient air temperature (°C)


Change in mean body temperature (°C)


Temperature of the clothing (°C)


Esophageal temperature (°C)


Rate of oesophageal temperature change (°C min−1)


Operative temperature (°C)


Mean radiant temperature (°C)


Rectal temperature (°C)


Mean skin temperature (°C)


Peak rate of oxygen consumption (L min−1)


Rate of oxygen consumption (L min−1)


Air velocity (m s−1)


Vastus lateralis


Rate of external work (W m−2)


Peak rate of external work (W)



The authors thank the volunteers for their participation and effort. This research was supported by a Discovery Grant from the Natural Sciences and Engineering Research Council (NSERC) of Canada (#386143-2010, held by O. Jay). Funding for the metabolic cart and dew point sensor were provided by a Canadian Foundation for Innovation (CFI) Infrastructure grant (co-applicant: O. Jay). N.M. Ravanelli was supported by a University of Ottawa Faculty of Health Sciences Research Bursary. M.N. Cramer is supported by a Postgraduate Scholarship (doctoral) from NSERC and an Excellence Scholarship from the University of Ottawa. Y. Molgat-Seon was supported by a University of Ottawa Master’s Scholarship. A.N. Carlsen is supported by NSERC and the University of Ottawa, Faculty of Health Sciences.

Conflict of interest

The authors report no competing interests, financial or otherwise.


  1. Blight J (1957) The relationship between the temperature in the rectum and of the blood in the bicarotid trunk of the calf during exposure to heat stress. J Physiol 136:393–403PubMedCentralGoogle Scholar
  2. Borg GA (1982) Psychophysical bases of perceived exertion. Med Sci Sports Exerc 14:377–381PubMedGoogle Scholar
  3. Cooper KE, Kenyon JR (1957) A comparison of temperatures measured in the rectum, œsophagus, and on the surface of the aorta during hypothermia in man. Br J Surg 44:616–619PubMedCrossRefGoogle Scholar
  4. Cotter JD, Taylor NA (2005) The distribution of cutaneous sudomotor and alliesthesial thermosensitivity in mildly heat-stressed humans: an open-loop approach. J Physiol 565:335–345PubMedCrossRefPubMedCentralGoogle Scholar
  5. Crewe H, Tucker R, Noakes T (2008) The rate of increase in rating of perceived exertion predicts the duration of exercise to fatigue at a fixed power output in different environmental conditions. Euro J Appl Physiol 103:569–577CrossRefGoogle Scholar
  6. CSEP (1996) Canadian Society for Exercise Physiology: certified fitness appraiser resource manual. CSEP, OttawaGoogle Scholar
  7. DuBois D, Dubois E (1916) A formula to estimate surface area if height and weight are known. Arch Intern Med 17:863CrossRefGoogle Scholar
  8. Ely BR, Ely MR, Cheuvront SN, Kenefick RW, DeGroot DW, Montain SJ (2009) Evidence against a 40°C core temperature threshold for fatigue in humans. J Appl Physiol 107:1519–1525PubMedCrossRefGoogle Scholar
  9. Ericson MO (1986) On the biomechanics of cycling. A study of joint and muscle load during exercise on the bicycle ergometer. Scand J Rehabil Med Suppl 16:1–43Google Scholar
  10. Fanger PO (1970) Thermal comfort. Danish Technical Press, CopenhagenGoogle Scholar
  11. Flouris AD (2011) Functional architecture of behavioural thermoregulation. Eur J Appl Physiol 111:1–8PubMedCrossRefGoogle Scholar
  12. Gephart FC, DuBois EF (1915) Fourth paper the determination of the basal metabolism of normal men and the effect of food. Arch Intern Med (Chic) 15:835–867CrossRefGoogle Scholar
  13. González-Alonso J, Mora-Rodríguez R, Coyle EF (2000) Stroke volume during exercise: interaction of environment and hydration. Am J Physiol Heart Circ Physiol 278:H321–H330PubMedGoogle Scholar
  14. Horstman DH, Horvath SM (1972) Cardiovascular and temperature regulatory changes during progressive dehydration and euhydration. J Appl Physiol 33:446–450PubMedGoogle Scholar
  15. Jay O, Kenny GP (2009) Current evidence does not support an anticipatory regulation of exercise intensity mediated by rate of body heat storage. J Appl Physiol 107:630–631PubMedCrossRefGoogle Scholar
  16. Jay O, Gariépy LM, Reardon FD, Webb P, Ducharme MB, Ramsay T, Kenny GP (2007) A three-compartment thermometry model for the improved estimation of changes in body heat content. Am J Physiol Regul Integr Comp Physiol 292:R167–R175PubMedCrossRefGoogle Scholar
  17. Mekjavic IB, Rempel ME (1990) Determination of esophageal probe insertion length based on standing and sitting height. J Appl Physiol 69:376–379PubMedGoogle Scholar
  18. Molnar GW, Read RC (1974) Studies during open-heart surgery on the special characteristics of rectal temperature. J Appl Physiol 36:333–336PubMedGoogle Scholar
  19. Nishi Y, Gagge AP (1970) Direct evaluation of convective heat transfer coefficient by naphthalene sublimation. J Appl Physiol 29:830–838PubMedGoogle Scholar
  20. Nybo L, Nielsen B (2001) Hyperthermia and central fatigue during prolonged exercise in humans. J Appl Physiol 91:1055–1060PubMedGoogle Scholar
  21. Ramanathan NL (1964) A new weighting system for mean surface temperature of the human body. J Appl Physiol 19:531–533PubMedGoogle Scholar
  22. Schlader ZJ, Simmons SE, Stannard SR, Mündel T (2011a) The independent roles of temperature and thermal perception in the control of human thermoregulatory behavior. Physiol Behav 103:217–224PubMedCrossRefGoogle Scholar
  23. Schlader ZJ, Simmons SE, Stannard SR, Mündel T (2011b) Skin temperature as a thermal controller of exercise intensity. Eur J Appl Physiol 111:1631–1639PubMedCrossRefGoogle Scholar
  24. Schlader ZJ, Stannard SR, Mündel T (2011c) Evidence for thermoregulatory behavior during self-paced exercise in the heat. J Therm Biol 36:390–396CrossRefGoogle Scholar
  25. Shiraki K, Konda N, Sagawa S (1986) Esophageal and tympanic temperature responses to core blood temperature changes during hyperthermia. J Appl Physiol 61:98–102PubMedGoogle Scholar
  26. Snellen JW (2000) An improved estimation of mean body temperature using combined direct calorimetry and thermometry. Eur J Appl Physiol 82:188–196PubMedCrossRefGoogle Scholar
  27. Stolwijk JA, Hardy JD (1966) Partitional calorimetric studies of responses of man to thermal transients. J Appl Physiol 21:967–977PubMedGoogle Scholar
  28. Tucker R, Rauch L, Harley YXR, Noakes TD (2004) Impaired exercise performance in the heat is associated with an anticipatory reduction in skeletal muscle recruitment. Pflugers Arch Eur J Physiol 448:422–430CrossRefGoogle Scholar
  29. Tucker R, Marle T, Lambert EV, Noakes TD (2006) The rate of heat storage mediates an anticipatory reduction in exercise intensity during cycling at a fixed rating of perceived exertion. J Physiol 574:905–915PubMedCrossRefPubMedCentralGoogle Scholar
  30. Vallerand A (1992) How should body heat storage be determined in humans: by thermometry or calorimetry? Eur J Appl Physiol O 65:286–294CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Nicholas M. Ravanelli
    • 1
  • Matthew N. Cramer
    • 1
  • Yannick Molgat-Seon
    • 1
    • 2
  • Anthony N. Carlsen
    • 3
  • Ollie Jay
    • 1
    • 4
  1. 1.Thermal Ergonomics Laboratory, School of Human KineticsUniversity of OttawaOttawaCanada
  2. 2.Health and Integrative Physiology LaboratorySchool of Kinesiology, University of British ColumbiaVancouverCanada
  3. 3.Sensorimotor Neuroscience Laboratory, School of Human KineticsUniversity of OttawaOttawaCanada
  4. 4.Exercise and Sports Science, Faculty of Health SciencesUniversity of SydneyLidcombeAustralia

Personalised recommendations