Carbon Monoxide and Physical Work Capacity

Abstract

Submaximal and maximal exercise capacity were compared in 16 subjects while breathing air and a 225-ppm carbon monoxide-air mixture, the latter resulting in a carboxyhemoglobin level of 20%. Maximal oxygen uptake decreased approximately proportional to the reduction in arterial oxygen content (24%) and irrespective of the arterial oxygen tension. The Incremental increases of heart rate and ventilation with exercise were greater in the subjects when breathing CO than air but peak ventilation was reduced with CO. Except for the latter, these responses are similar to that found with hypobaric hypoxia.