Ventilatory response to exercise in aged runners breathing He-O2 or inspired CO2

Abstract

The ventilatory response to exercise below ventilatory threshold (VTh) increases with aging, whereas above VTh the ventilatory response declines only slightly. We wondered whether this same ventilatory response would be observed in older runners. We also wondered whether their ventilatory response to exercise while breathing He-O2 or inspired CO2would be different. To investigate, we studied 12 seniors (63 ± 4 yr; 10 men, 2 women) who exercised regularly (5 ± 1 days/wk, 29 ± 11 mi/wk, 16 ± 6 yr). Each subject performed graded cycle ergometry to exhaustion on 3 separate days, breathing either room air, 3% inspired CO2, or a heliox mixture (79% He and 21% O2). The ventilatory response to exercise below VTh was 0.35 ± 0.06 l · min−1 · W−1and above VTh was 0.66 ± 0.10 l · min−1 · W−1. He-O2 breathing increased ( P < 0.05) the ventilatory response to exercise both below (0.40 ± 0.12 l · min−1 · W−1) and above VTh (0.81 ± 0.10 l · min−1 · W−1). Inspired CO2 increased ( P < 0.001) the ventilatory response to exercise only below VTh (0.44 ± 0.10 l · min−1 · W−1). The ventilatory responses to exercise with room air, He-O2, and CO2 breathing of these fit runners were similar to those observed earlier in older sedentary individuals. These data suggest that the ventilatory response to exercise of these senior runners is adequate to support their greater exercise capacity and that exercise training does not alter the ventilatory response to exercise with He-O2 or inspired CO2 breathing.