In conclusion, maximal arm crank exercise resulted in an impressive improvement in P&02 (85 to 97 mm Hg) with no significant changes in Sa02 and P(A-a)02 (3 to 5 mm Hg) and an appropriate trending decrease in Vd/Vt (0.22 to 0.17). Compared to cycle exercise, arm crank exercise elicited a higher Pa02, Sa02, Vd/Vt, and lower P(A-a)02. Maximal arm crank exercise represents a submaximal cardiopulmonary stress, when compared to maximal leg exercise. The differences in gas exchange observed at peak exercise between arm crank and leg exercise may, for the most part, also reflect the submaximal cardiopulmonary stress elicited by arm crank exercise. proventil inhaler

However, the persistence of these differences even at comparable levels of Vo2 suggests that factors other than the level of Vo2 may be operative. These factors may include alveolar ventilation, C02 production, ventilation-per-fusion inequality, diffusion and control of breathing. The role that maximal arm crank exercise may play in the evaluation of gas exchange abnormalities in patients with cardiac and/or pulmonary disease is currently under investigation in our laboratory.