Rectal temperature, heart rate and body weight loss in a master athlete during a summer ultra-marathon-A Case Report

The present study measures rectal temperature, heart rate, body weight loss, and volume of fluid and food intake in a 50-year-old male athlete who ran a 77-km ultra-marathon during the summer. The average dry-bulb temperature, relative humidity and wet-bulb globe temperature (WBGT) during the marathon were 28.5±1.4℃, 53.8±5.2% and 28.9±2.1℃, respectively. The average heart rate and total estimated energy consumption during the entire 10 h and 45 min run were 133±17 beats per min and 6,475 kcal, respectively. Rectal temperature during the run gradually increased and was elevated by 2.6℃ by the end of the marathon. Immediately after flushing with cold water over the neck or head during the run, the heart rate immediately increased and rectal temperature slightly decreased at two minutes later. Flushing with cold water therefore helped prevent the core body temperature from rising while running in an ultra-marathon under summer heat. However, the sudden autonomic increase in heart rate as a response to flushing with cold water might be the cause of sudden death that can occur among athletes competing in ultra-marathons under hot environmental conditions.