title: Aural canal, esophageal, and rectal temperatures during exertional heat stress and the subsequent recovery period.
abstract: BACKGROUND
  The measurement of body temperature is crucial for the initial diagnosis of exertional heat injury and for monitoring purposes during a subsequent treatment strategy. However, little information is available about how different measurements of body temperature respond during and after exertional heat stress.
  
  
  OBJECTIVE
  To present the temporal responses of aural canal (T(ac)), esophageal (T(es)), and rectal (T(re)) temperatures during 2 different scenarios (S1, S2) involving exertional heat stress and a subsequent recovery period.
  
  
  METHODS
  Randomized controlled trial.
  
  
  METHODS
  University research laboratory.
  
  
  METHODS
  Twenty-four healthy volunteers, with 12 (5 men, 7 women) participating in S1 and 12 (7 men, 5 women) participating in S2.
  
  
  METHODS
  The participants exercised in the heat (42 degrees C, 30% relative humidity) until they reached a 39.5 degrees C cut-off criterion, which was determined by T(re) in S1 and by T(es) in S2. As such, participants attained different levels of hyperthermia (as determined by T(re)) at the end of exercise. Participants in S1 were subsequently immersed in cold water (2 degrees C) until T(re) reached 37.5 degrees C, and participants in S2 recovered in a temperate environment (30 degrees C, 30% relative humidity) for 60 minutes.
  
  
  METHODS
  We measured T(ac), T(es), and T(re) throughout both scenarios.
  
  
  RESULTS
  The T(es) (S1 = 40.19 +/- 0.41 degrees C, S2 = 39.50 +/- 0.02 degrees C) was higher at the end of exercise compared with both T(ac) (S1 = 39.74 +/- 0.42 degrees C, S2 = 38.89 +/- 0.32 degrees C) and T(re) (S1 = 39.41 +/- 0.04 degrees C, S2 = 38.74 +/- 0.28 degrees C) (for both comparisons in each scenario, P < .001). Conversely, T(es) (S1 = 36.26 +/- 0.74 degrees C, S2 = 37.36 +/- 0.34 degrees C) and T(ac) (S1 = 36.48 +/- 1.07 degrees C, S2 = 36.97 +/- 0.38 degrees C) were lower compared with T(re) (S1 = 37.54 +/- 0.04 degrees C, S2 = 37.78 +/- 0.31 degrees C) at the end of both scenarios (for both comparisons in each scenario, P < .001).
  
  
  CONCLUSIONS
  We found that T(ac), T(es), and T(re) presented different temporal responses during and after both scenarios of exertional heat stress and a subsequent recovery period. Although these results may not have direct practical implications in the field monitoring and treatment of individuals with exertional heat injury, they do quantify the extent to which these body temperature measurements differ in such scenarios.
authors.affiliation: School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada.
authors.forename: Daniel
authors.initials: D
authors.lastname: Gagnon
authors.forename: Bruno B
authors.initials: BB
authors.lastname: Lemire
authors.forename: Ollie
authors.initials: O
authors.lastname: Jay
authors.forename: Glen P
authors.initials: GP
authors.lastname: Kenny
mesh_terms: D000704:Analysis of Variance; D001831:Body Temperature / Q000502:physiology*; D001833:Body Temperature Regulation / Q000502:physiology; D003080:Cold Temperature; D004424:Ear Canal; D004947:Esophagus; D005260:Female; D018882:Heat Stress Disorders / Q000503:physiopathology*; D006801:Humans; D007101:Immersion; D008297:Male; D005082:Physical Exertion / Q000502:physiology*; D012007:Rectum; D012146:Rest; D055815:Young Adult