Comparison of tympanic and rectal temperatures in adults at rest and during exercise

Wang, Bei
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The tympanic membrane has been proposed as a possible locus for accurate recording of core temperature, because of its proximity to the brain and the carotid artery. Infrared tympanic thermometry (ITT) has been developed as a new method for measuring tympanic temperature (T[subscript ty]); however, ITT has not been extensively evaluated against rectal temperature. This study measured tympanic and rectal temperatures in 13 college-aged subjects (5 men and 8 women) at rest and during exercise in a thermoneutral environment (22-240C). Subjects first performed 90 min steady state exercise at 55% VO2peak. This was followed by a 30 min time trial which required subjects to perform the amount of work equivalent to 30 minutes at 60% of their VO2peak. Although a statistically significant correlation was observed between tympanic and rectal temperatures at rest or exercise, the variance in tympanic temperature accounted for only 36% of the total variance in rectal temperature and the standard error of estimate was high (±0.48). Moreover, rectal temperature was 0.90C (P<0.05) higher than tympanic temperature at all time points for men and women combined, confirming that tympanic and rectal temperatures do not agree. Tympanic temperature was stable during steady state exercise and increased gradually during the time trial for both men and women; however, rectal temperature increased during steady state exercise and then decreased slightly in men, but continued to increase for women during the time trial. These results demonstrate that tympanic temperature responses during exercise lag behind rectal temperature responses and that men and women have somewhat divergent temperature responses to exercise. In conclusion, tympanic temperature is not a good predictor of rectal temperature in adults at rest or during exercise.

Health and human performance, Exercise and sport science