Core Temperature Estimation Using The CORETm Body Temperature Sensor During A 5 Km Running Time-trial

Abstract

Monitoring of core body temperature (CT) during exercise may be useful to optimize pacing and performance and prevent heat-related illnesses. Athletes are left with very few options when it comes to the measurement of CT during out-of-doors exercise conditions. Moreover, the available technology is either expensive or invasive, both of which are a deterrent to athletes. Recently, a non-invasive, affordable, wearable, compact, light, rechargeable and wireless thermal energy transfer sensor has been introduced into the market. When paired with heart rate, the manufacturer claims that the device can estimate CT with an accuracy of ±0.21 °C. PURPOSE: Compared measurements of CT obtained with a gastrointestinal pill (GP) to those estimated with the CORETM thermal energy transfer sensor during a sitting period followed by a running time-trial. METHODS: This is an ongoing study and preliminary findings are henceforth reported. Six participants (4 men, 2 women) aged 26 ± 4 yrs, with a fat-free mass (FFM) of 55 ± 8 kg, underwent a 120 min seated resting period at 20-21 °C followed by a 5 km running time-trial at 30 °C, 50% relative humidity. Participants ingested a GP 10 h prior to reporting to the laboratory. The CORETM sensor was worn according to the manufacture’s instructions, i.e., 20 cm below the armpit, and paired with a heart rate monitor. Following 20 min of sitting, participants ingested 7.5 mL/kg FFM of cold water (~ 4 °C). Measurements of CT were taken every 20 min during the sitting period and every min during the TT. RESULTS: Whereas according to the CORETM CT increased by 0.13 ± 0.08 °C during the sitting period, a decrease of 0.18 ± 0.11 °C was detected with GP. A mean bias (CORETM - GP) of - 0.22 °C at a CT of 37 °C with each additional increase in CT of 0.1 °C associated with an error of - 0.12 °C, were observed during the sitting period. A mean bias between devices of - 0.55 °C was observed during the time-trial. The mean rates of increase in CT during exercise were respectively of 0.07 ± 0.04 and 0.08 ± 0.04 °C/min for the CORETM and GP. CONCLUSION: Our results indicate that, compared with measurements derived from a GP, the CORETM 1) underestimates both CT and the rate of change in CT during a sitting period comprising cold fluid ingestion and; 2) underestimates CT but adequately estimates the rate of change in CT during a 5 km time-trial in the heat.