Core-Temperature Sensor Ingestion Timing and Measurement Variability

Abstract

Context: Telemetric core-temperature monitoring is becoming more widely used as a noninvasive means of monitoring core temperature during athletic events.Objective: To determine the effects of sensor ingestion timing on serial measures of core temperature during continuous exercise.Design: Crossover study. Setting: Outdoor dirt track at an average ambient temperature of 4.46C 6 4.16C and relative humidity of 74.1% 6 11.0%.Patients or Other Participants: Seven healthy, active participants (3 men, 4 women; age 5 27.0 6 7.5 years, height 5 172.9 6 6.8 cm, body mass 5 67.5 6 6.1 kg, percentage body fat 5 12.7% 6 6.9%, peak oxygen uptake [V O 2peak ] 5 54.4 6 6.9 mLNkg 21 Nmin 21 ) completed the study.Intervention(s): Participants completed a 45-minute exercise trial at approximately 70% V O 2peak . They consumed coretemperature sensors at 24 hours (P1) and 40 minutes (P2) before exercise.Main Outcome Measure(s): Core temperature was recorded continuously (1-minute intervals) using a wireless data logger worn by the participants. All data were analyzed using a 2-way repeated-measures analysis of variance (trial 3 time), Pearson product moment correlation, and Bland-Altman plot.Results: Fifteen comparisons were made between P1 and P2. The main effect of time indicated an increase in core temperature compared with the initial temperature. However, we did not find a main effect for trial or a trial 3 time interaction, indicating no differences in core temperature between the sensors (P1 5 38.36C 6 0.26C, P2 5 38.36C 6 0.46C).Conclusions: We found no differences in the temperature recordings between the 2 sensors. These results suggest that assumed sensor location (upper or lower gastrointestinal tract) does not appreciably alter the transmission of reliable and repeatable measures of core temperature during continuous running in the cold.Key Words: thermal response, continuous exercise, body temperature Key Points N The telemetric core-temperature sensors recorded consistent core-temperature data independent of the time of ingestion and the assumed location of the sensor in the lower gastrointestinal tract during continuous running in the cold.N The wireless core-temperature sensors could give health care providers a reliable way to track core-temperature changes in athletes during sporting events and to respond more effectively to heat-related symptoms in at-risk participants.T he practical ability to monitor core body temperature might be critical in athletic settings where the probability for developing heat or cold illness is elevated 1 and athletic performance subsequently decreases. 2 The more common methods for measuring core temperature include pulmonary artery, esophageal, rectal, and temporal measurements, which are impractical in a sport or occupational setting. Each of these measurement techniques has different applications for various scenarios. Pulmonary arterial blood temperature is measured with insertion of a catheter into the right pulmonary artery. 3 Measuring esophageal temperature involves positioni...

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