This experiment investigates the validity of six thermometers with different measuring sensors, operation and site of application, to estimate core temperature (Tc) in comparison to an ingestible thermometric sensor based on quartz crystal technology. Measurements were obtained before, during and after exercise in the heat, controlling the presence of air-cooling and skin sweating. Twelve well-trained men swallowed the ingestible thermometer 6 h before the trial. After pre-exercise resting measurements at 20 °C, subjects entered a heat chamber held at 40 °C. Exercise in the heat consisted of 60 min of pedalling on cycle ergometer at 90% of the individually determined first ventilatory threshold. Results reveal that wind and skin sweat invalidate the use of skin infrared thermometry to estimate Tc during exercise in the heat. However, better Tc estimations were obtained in wind-restricted situations. We detected important differences between same-technology devices but different models and brands. In conclusion, there are important limitations to assess Tc accurately using non-invasive thermometers during and after exercise in the heat. Because some devices showed better validity than others did, we recommended using tympanic Braun®, and non-contact skin infrared Medisana® or Visiofocus® in wind-restricted and no sweat conditions to estimate Tc during exercise in the heat.
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We thank José Fajardo Rodríguez and Javier Sánchez Prieto for their excellent technical assistance with laboratory apparatus and assistance to the athletes. We also acknowledge the dedicated effort, commitment and professionalism of the selected group of athletes who took part in this research.
Associate Editor Jane Grande-Allen oversaw the review of this article.
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Morán-Navarro, R., Courel-Ibáñez, J., Martínez-Cava, A. et al. Validity of Skin, Oral and Tympanic Temperatures During Exercise in the Heat: Effects of Wind and Sweat. Ann Biomed Eng 47, 317–331 (2019). https://doi.org/10.1007/s10439-018-02115-x
- Indoor exercise
- Heat illness
- Body temperature