Differences in cardio-respiratory responses to exhaustive exercise between athletes and non-athletes

To study the factors limiting the O2 supply in heavy exercise, O2 uptake at exhaustion was determined by progressive loading method with a bicycle ergometer in 33 well-trained male runners and 34 male sedentary adults. Pulmonary ventilation, oxygen removal, respiratory rate, tidal volume, pulmonary diffusing capacity, alveolar-capillary oxygen difference, cardiac output, arterial-venous oxygen difference, stroke volume and heart rate were measured. It was found that pulmonary diffusing capacity, cardiac output and stroke volume were correlated with the difference in O2 uptake at exhaustion between athletes and non-athletes.