Abstract

The purpose of this study was to compare tympanic (measured by infrared thermometry; Tty-IRED) with rectal and esophageal temperatures (TREC and TES) during exercise in the heat. During Experiment 1, nine subjects pedaled for 55 min in a hot-dry environment (37 °C; 27 % humidity) in still-air (< 0.2 m/s) and for 10 additional min using water ingestion, wind and ice to cool them down. During Experiment 2, subjects pedaled for 90 min in a similar environment but with airflow at 2.5 m/s. Pearson correlation coefficients (r) and Bland-Altman plots were calculated. In Experiment 1, Tty-IRED and TREC were highly correlated (r = 0.83; p < 0.001) with close agreement (− 0.08 ± 0.4°C). Overall Tty-IRED was significantly correlated with TES (r = 0.91; p < 0.001). Cold water ingestion did not affect Tty-IRED or TREC but lowered TES. Wind and ice application lowered Tty-IRED below TREC (p < 0.05). During Experiment 2, Tty-IRED was lower than TREC (p < 0.05) and the difference increased throughout exercise as hyperthermia developed resulting in low agreement (− 1.01 ± 1.1°C). In conclusion, Tty-IRED dangerously underestimates TREC when exercising in a hot environment with airflow or during a cooling treatment. However, it could correctly detect hyperthermia during exercise in a hot still-air environment. Verf.-Referat