Ventilatory and thermoregulatory responses during continuous exercise in the heat

Abstract

The objectives of this study were to study the effects of heat and continuous exercise on cardiorespiratory function and thermoregulatory responses and to compare the relationship between body ventilation and thermoregulation at rest and during continuous exercise in the heat. Six sedentary volunteers with average age 23.33±1.02 years participated in 2 experiments each: 25-min sitting comfortably and exercising by bicycle at 75 Watt continuous workload until 70% HRR was approached in the heat chamber at 44.19±0.13ºC, 58.62±0.47%RH. The aforementioned parameters were measured and recorded at five-minute intervals until the end of the study. The level for statistical difference was set at α<0.05. It was found that minute ventilation, oxygen consumption, respiratory rate, heart rate, skin temperatures, and body temperature increased significantly during exercise in the heat (p<0.05) while there was no significant difference at rest (p>0.05). Rectal temperature did not change at rest and changed in minimal range during exercise under heat stress (p>0.05). Mean arterial pressure did not change throughout both of the studies. RER were kept constant in range of 0.9-1 in both trials. RPE, thermal sensation, and thermal discomfort did not change at rest but gradually increased during exercise in the heat. It was concluded that the body dissipates additional heat out of the body via skin and ventilation to keep homeostasis of thermoregulation during exercise in the heat which causes a non-significant difference of rectal temperature throughout the study of exercise under heat stress.;"การศึกษานี้มีวัตถุประสงค์เพื่อศึกษาผลของความร้อนและการออกกำลังกายอย่างต่อเนื่อง ภายใต้ความร้อนต่อการทำงานของระบบไหลเวียนและการหายใจ และการตอบสนองทางด้าน สมดุลอุณหภูมิกาย ในชายไทยผู้มีสุขภาพแข็งแรง การทดลองกระทำโดยให้อาสาสมัครจำนวน 6 คน มีอายุเฉลี่ย 23.33±1.02 ปี ร่วมทำการทดลอง 2 ครั้ง คือ นั่งเฉยๆในห้องซาวน่าที่ม"