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Abstract

Background: As the intensity of exercise increases, the risk of incidences for exertional heat illness (EHI) continues to climb. The National Athletic Trainers Association (NATA) has set an official position statement; stating a “gold standard” for obtaining core body temperature is via rectal thermometry. It has been reported that other field-expedient methods of obtaining core body temperature (oral, axillary, tympanic, temporal) are invalid or unreliable sources after intense exercise in hot temperature regions. Purpose: To determine if a relationship exists between rectal temperature measurements and tympanic temperature measurements during intensive long bouts of exercise. Design: Controlled Laboratory Study. Setting: Human performance laboratory (FAST lab) located on campus of a public 4-year institution. Subjects: Two highly trained and experienced cyclists. Both subjects were male with an average age of 25.5±2.5. Methods: Subjects took the George Non-Exercise Test (GNET)to establish their predicted exercise fitness level. Based on their height, weight and age, subjects predicted VO2 max and predicted Max Watts (EW) were also computed. Subjects were instructed on how to self-insert the rectal and tympanic thermocouples. Participants began their cycling exercise at 40% of their EW. Intensity increased at a rate of 10% every five minutes until core body temperature reached approximately 38.3˚ Centigrade (101˚ Fahrenheit) or the subject started experiencing volitional fatigue. Researchers recorded temperature measurements every second. Results: As hypothesized, a statistically significant difference was found between the two temperatures (rectal and tympanic). The one-way ANOVA analysis indicated there was a significant difference between rectal and tympanic temperatures: F = 1635.65, df = 1/3720, p < 0.01. However, after performing a correlation test, researchers found that the temperatures were also positively correlated to one another: r = 0.964, p < 0.01. Conclusions: There is a strong correlation, but a significant difference between both the rectal and tympanic temperature measurements. It is premature to make conclusive recommendations for a new standard or protocol.