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Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas and The University of Texas Southwestern Medical Center, Dallas, Texas 77231
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 CO2
would 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
1
and 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.
control of breathing during exercise; ventilatory responses to loaded and unloaded breathing; work of breathing during exercise
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