Power relative to body mass best predicts change in core temperature during exercise-heat stress

Oliver Gibson, Ashley Willmott, Carl James, Mark Hayes, Neil Maxwell

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Controlling internal temperature is crucial when prescribing exercise-heat stress, particularly during interventions designed to induce thermoregulatory adaptations. This study aimed to determine the relationship between the rate of rectal temperature (T ­rec) increase, and various methods for prescribing exercise-heat stress, to identify the most efficient method of prescribing isothermic heat acclimation (HA) training. Thirty-five males cycled in hot conditions (40°C, 39%R.H.) for 29±2 min. Subjects exercised at 60±9%\s\up8(.O2peak, with methods for prescribing exercise retrospectively observed for each participant. Pearson product moment correlations were calculated for each prescriptive variable against the rate of change in T­rec (°C.hr-1), with stepwise multiple regressions performed on statistically significant variables (p<0.05). Linear regression identified the predicted intensity required to increase Trec by 1.0-2.0°C between 20-45 min periods, and the duration taken to increase Trec by 1.5°C in response to incremental intensities to guide prescription. Significant (p<0.05) relationships with the rate of change in Trec were observed for prescriptions based upon relative power (W.kg-1; r=0.764), power (%Powermax; r=0.679), RPE (r=0.577), \s\up8(.O2 (%\s\up8(.O2peak; r=0.562), HR (%HRmax; r=0.534), and TS (r=0.311). Stepwise multiple regressions observed relative power and RPE as variables to improve the model (r=0.791), with no improvement following inclusion of any anthropometric variable. Prescription of exercise under heat stress utilizing power (W.kg-1 or %Powermax), has the strongest relationship with the rate of change in Trec with no additional requirement to correct for body composition within a normal range. Practitioners should therefore prescribe exercise intensity using relative power during isothermic HA training to increase Trec efficiently and maximize adaptation.
Original languageEnglish
Pages (from-to)403-414
Number of pages12
JournalJournal of Strength and Conditioning Research
Issue number2
Publication statusPublished - 20 May 2016

Bibliographical note

This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND), which permits downloading and sharing the work provided it is properly cited. The work cannot be changed in any way or used commercially.


  • Heat adaptation
  • Acclimatization
  • Thermoregulation
  • Heat Production
  • Core temperature
  • Relative Power


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