Validity Of A Novel Body Temperature Wearable Device During The Falmouth Road Race

Valid core temperature (TCORE) assessment methods available during exercise in the heat include rectal, gastrointestinal (TGI), and esophageal temperature. However, these methods have limitations in a field setting. A novel wearable body temperature device (TDEV) to predict TCORE continuously has emerged, yet the validity and reliability remains unclear. PURPOSE: To examine the validity of TDEV compared to TGI during and at the finish of a warm weather road race. METHODS: Sixteen runners (n = 10 males, n = 6 females) ((mean ± standard deviation) age: 48 ± 13 years, VO2max: 47.98 ± 7.71 ml·kg-1·min-1) ran a self-paced 7.1-mile road race in hot, humid conditions (WBGT: 28.4 °C ± 1.0 °C). TDEV and TGI were monitored during the race and at race finish. Repeated measures ANOVA with Bonferroni post hoc comparisons were used to compare TDEV and TGI during the race. Linear regression, mean bias, limits of agreement (LOA), typical error of the estimate (TEE), and interpretation of the effect, examined the relationship between TDEV and TGI during and at race finish. Significance was set to p < 0.05. RESULTS: During the race, average peak TGI was 39.39 °C (38.38-40.6 °C). No interaction was exhibited between time and device (p = 0.087). Good agreement and a high, positive relationship (95% LOA ± 0.94 °C, r = 0.84) was displayed between TDEV and TGI during the race. TDEV showed fair agreement and a low, positive relationship (TGI: 95% LOA ± 1.20 °C, r = 0.40) compared to TGI at race finish. The TEE suggests that the mean bias values may be attributed to error. CONCLUSIONS: During a warm weather race, TDEV displayed overall good agreement with a mean bias of -0.21 ± 0.48 °C compared to TGI and fair agreement at race finish with a mean bias of -0.10 ± 0.6 °C, therefore it is not equipped to diagnose exertional heat stroke. Continued validation and enhancement of the algorithm for TDEV in future, adequately powered studies with varying populations, environmental conditions, intensities, equipment and clothing worn, and at the upper limits of hyperthermia (i.e. >39.5 °C) are needed to establish appropriate validity for use during training and competition.