Modeling physiological and thermoregulatory responses during an Olympic triathlon.

Olympic triathlons are physiologically challenging with varying environmental conditions and physical demands through three events that create a complex dynamic affecting performance and injury risk. Mathematical models provide useful insights into these physiological and thermal responses imposed on individuals and allow for risk mitigation strategies, after action assessments, and for potential training optimization. The purpose of this study was to evaluate thermoregulatory responses continuously during Olympic triathlon for athletes using a mathematical model. Methods: The Health Risk Prediction Model (HRP), a validated 14-segment mathematical model was used to predict physiological and thermoregulatory outcomes during each phase of an Olympic triathlon. Simulated inputs were derived from the observed conditions from the Summer Olympic Games - Rio de Janeiro - 2016, during the men's triathlon (August 18, 2016, starting at 11:00 a.m.). Environmental conditions were: water temperature of 25 °C, air temperature 28 °C, relative humidity 50 %, and 5 m/s wind speed. Metabolic rates were calculated based on times to finish each phase (swimming 36 min at 900 kcal/h, cycling 72 min at 1000 kcal/h, and running 60 min at 900 kcal/h), associated transition times (3 and 1.5 min), and the entire collective event (2 h, 52 min, 30 s). Results and Discussion: This work represents an initial effort to comprehensively model physiological and thermoregulatory effects during an extraordinarily complex event, the Olympic triathlon. Physiological modeling provides insights into the interrelated changes occurring during each phase of exercise and the transitions between them. Lastly, these model results focus additional research questions.