Core temperature measurement: Methods and current insights

Climatic injuries, including hypothermia, hyperthermia and heat stroke, are common in many sports activities. Body core temperature (T_o) measurement for the sportsperson can influence individual performance and may help to prevent injuries. Monitoring internal body T_o accurately requires invasive methods of measurement. The mercury thermometer, most commonly used to measure oral temperature (T_oral), has been almost exclusively the only instrument for measuring T_c since the 18th century. Rectal (T_re) and oesophageal temperatures (T_oes) have been the most preferred measurement sites employed in thermoregulatory investigations. However, these measurement sites (T_re, T_oes, T_oral), and the methods used to measure T_c at these sites, are not convenient. T_oral measurements are not always possible or accurate. T_oes is undesirable because of the difficulty of inserting the thermistor, irritation to nasal passages and general subject discomfort. T_re is not suitable under many circumstances as it is labour intensive and has a prolonged response time. However, T_re remains the most accurately available method for monitoring T_c in thermal illness that occurs during sports activities. In addition, T_re and T_oes require wire connections between the thermistor and the monitoring device. The purpose of this paper is to review the various existing methods of T_c measurements in order to focus on the breakthrough needed for a simple, noninvasive, universally used device for T_c measurement which is essential for preventing climatic injuries during sports events.