PHYSIOLOGICAL-RESPONSES TO A COLD, WET, AND WINDY ENVIRONMENT DURING PROLONGED INTERMITTENT WALKING

The potentially deleterious influence of body cooling on the thermoreg ulatory and metabolic responses to prolonged walking exercise has not been established. To address this problem, 10 men completed a 6-h inte rmittent (15 min rest, 45 min exercise) walking protocol in a thermone utral (+15 degrees C) condition (Neutral) and a cold (+5 degrees C), w et, and windy condition (Cold). The first two exercise periods were co nducted at a higher intensity (Higher, 6 km/h and 10% incline) than th e subsequent four exercise periods (Lower, 5 km/h and 0% incline). Rec tal temperature was lower and heart rate no different in Cold compared with Neutral, whereas the following were higher: oxygen consumption, respiratory exchange ratio, plasma norepinephrine and epinephrine, and blood lactate and glucose. There was no environmental influence on th ese variables during Higher. In conclusion, heat production during Low er was not sufficient to offset heat loss to the cold environment, and the resulting reduction in rectal temperature and metabolic perturbat ions may be detrimental if exercise is prolonged.