Maximum ventilatory performance and its limiting factors

¹ Department of Medicine, Medical College of Virginia, Richmond, Virginia

Pressure-volume-flow relationships during maximum-effort expirations and inspirations were analyzed in 27 studies on 7 superbly conditioned nonsmoking athletes, 5 nonathletic nonsmokers, and 7 nonathletic smokers. The athletes had larger mean vital capacity and maximum breathing capacity as well as higher airflow during the first half of forced inspiration than the other subjects. In contrast, smokers exhibited lower mean vital capacity, lower air flows, and higher transpulmonary pressures during forced expirations than the nonsmokers. Transpulmonary pressures at peak flow during maximal forced expirations were higher in the present study than those commonly reported and may have been due to the technique used to perform this maneuver. Limiting factors apparently operate to prevent superior athletic conditioning from effecting comparable improvement in ventilatory performance. The favorable alterations in this performance which were observed in the athletes do not seem sufficient to explain their greater endurance. Mild decreases in ventilatory performance were exhibited by the smokers, probably due to the chronic effects of cigarette smoking on the pulmonary airways.

Submitted on April 25, 1963