Accuracy of the EXERGEN TAT-5000 Temporal Scanner in Monitoring Core Body Temperature During and After Physical Exercise in a Hot Environment

This study assessed the accuracy of the EXERGEN TAT-5000 temporal scanner (TEXERGEN) (EXERGEN, Watertown, MA, USA) for estimating core body temperature (TCORE) during rest, progressive cycling exercise, and post-exercise recovery in a hot environment. Fourteen healthy adults (7 men and 7 women) completed a laboratory protocol consisting of 10 min of rest, 60 min of cycling, and 25 min of recovery at an ambient temperature of 32 °C and a relative humidity of 60%. Gastrointestinal temperature (TGi), measured via telemetry capsules, served as the criterion method. A total of 5376 paired measurements were analyzed. Throughout the protocol, TEXERGEN systematically underestimated TCORE compared with TGi, with mean biases between −0.35 °C and −1.15 °C. The overall 95% confidence intervals ranged from ±0.91 to ±1.43 °C, demonstrating poor precision. Limits of agreement were wide (from −2.00 to 0.87 °C), and concordance correlation coefficients (CCC) indicated poor agreement (CCC < 0.90 in all conditions). The underestimation was more pronounced during exercise and recovery, when TCORE remained high according to TGi but decreased according to TEXERGEN. These results indicate that TEXERGEN does not monitor TCORE accurately under heat stress or during rapid metabolic changes. Therefore, the use of this device is not recommended during and after exercises under environmental heat stress.