Aural canal, esophageal, and rectal temperatures during exertional heat stress and the subsequent recovery period.
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.
Gagnon
Daniel
D
School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada.
Lemire
Bruno B
BB
Jay
Ollie
O
Kenny
Glen P
GP
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