Physiological effects of cold air inhalation during exercise.

Selected physiological responses of six normal subjects were oberved, during rest and exercise, while they breathed a) ambient, and b) cold (-35 degrees C) air. All experiments were 10 min in duration, and the exercise experiments consisted of pedaling a bicycle ergometer at loads requiring approximately 60% and 75% of each subject's VO2 max. Heart rates and minute ventilations during the most strenous exercise averaged approximately 170 bpm and 70 l, respectively. Diastolic blood pressure was significantly lower, during cold air inhalation. Oxygen uptake, respiration rate, and rectal temperature were not affected by cold air breathing; and no subject complaints were attributable to cold air inhalation. Recent studies in the literature suggest that cold air is not fully warmed in the upper respiratory passages; however, the present study observed only slight changes in measured physiological responses to rest and exercise with cold air breathing.