Physiological Responses of Distance Runners during Normal and Warm Conditions

The aim of this study was to determine the effects of elevated climate temperature on the exercise-induced physiological responses in distance runners. Ten competitive distance runners (age: 17.75 ± 0.68 yrs) participated in a counter balanced cross over design that consisted of performing a treadmill run (75% VO₂ max) for 30 min under normal (18 ± 1C° RH 26% ± 2) and warm (40 ± 1°C; RH 12% ± 2) conditions, separated by 15 days. Measures of blood sodium, blood potassium, blood pressure, heart rate, body temperature, blood sugar, and rating of perceived exertion (RPE) were obtained at 5-min intervals (0, 5, 10, 15, 20, 25, and 30 min) from the onset of exercise. Results of this study showed an increase in sodium and potassium concentrations at the beginning of exercise that decreased towards the end of exercise and a decrease in blood sugar at the beginning and an increase at the end. Blood pressure, heart rate, body temperature, and RPE increased all the way to the end of the exercise. These findings indicate that coaches who are responsible for athletes exercising and/or training in warm dry weather should take the athletes' physiological responses seriously and recalculate their training loads according to weather conditions.