Effect of ambient temperature on recovery from muscular exercise

Abstract

Sri Lanka has high daytime ambient temperatures throughout the year that are too high to allow dissipation of body heat by non-evaporative methods. The predominant method of heat loss in the tropics, the evaporative heat loss, is also limited because of high humidity caused by wet conditions. Therefore, the limitations to thermoregulation could lead to poor work performance. This study was aimed at investigating the effect of two different ambient temperatures (28.5°C with relative humidity of 73.4% and 22.6°C with relative humidity of 64%) on the recovery from muscular exercise. The study was conducted on 20 sedentary male university students aged 21-24 years (mean 22.5 years). They were made to perform standard exercise for six minutes on a bicycle ergometer at two different ambient temperatures on two different occasions. Physiological parameters including heart rate, pulmonary ventilation, axillary temperature, systolic and diastolic blood pressures were measured at rest and during recovery at five-minute intervals up to 20 minutes. Results showed that although the recovery pattern of cardio-respiratory changes were similar at these two ambient temperatures, the values for heart rate, pulmonary ventilation and systolic blood pressure at the end of exercise at higher ambient temperature with higher relative humidity were significantly higher. At least in the study situation, the lower ambient temperature would be more favourable with regard to cardio-respiratory changes while performing moderate exercise. These findings point to the importance of planning different schedules of work and resting periods for different environmental conditions, especially, those with high ambient temperature and high relative humidity.