Gas Exchange During Maximal Upper Extremity Exercise: Discussion (4)
The determinants for PkOs include those factors which affect the Pa02 and/or the P(A-a)02. At peak exercise, similar values for PaO£ flable 3) would suggest that factor(s) which affect the P(A-a)02 magnitude difference between arm crank and cycle exercise (5 mm Hg vs 21 mm Hg, respectively) must be responsible for the observed Pa02 differences. ventolin 100 mcg
At a comparable Vo2, the difference in Pa02 can be explained in part by a relative alveolar hyperventilation during arm crank exercise compared to lower extremity exercise. This increase in Pa02 (arm crank = 102 mm Hg vs cycle = 95 mm Hg) (Table 3), is best explained by hyperventilation secondary to increases in C02 production in subjects with normal ventilatory responses (Table 2). Also, as shown by the alveolar air equation, alveolar Po2 is necessarily higher (at the same PCOJ when the R is higher. The higher R is a reflection of the increase in C02 production, possibly resulting from the greater lactate production at a comparable power for arm crank vs leg exercise. In addition, factors which affect the P(A-a)02 magnitude difference between arm crank and cycle exercise (5 mm Hg vs 14 mm Hg, respectively) must also be responsible for the Pa02 difference observed at a comparable Vo2.