Aging is associated with deterioration in the structure and function of the pulmonary circulation. We characterized the lung diffusing capacity for carbon monoxide (DLCO), alveolar-capillary membrane conductance (DmCO), and pulmonary-capillary blood volume (VC) response to discontinuous incremental exercise at 25, 50, 75, and 90% of peak work (Wpeak) in four groups: 1) Young [27 ± 3 y, maximal oxygen consumption (V̇O2max) 110 ± 18% age-predicted]; 2) Young Highly-Fit (27 ± 3 y, V̇O2max 147 ± 8% age-predicted); 3) Old (69 ± 5 y, V̇O2max 116 ± 13% age-predicted); and 4) Old Highly-Fit (65 ± 5 y, V̇O2max 162 ± 18% age-predicted). At rest and at 90% Wpeak, DLCO, DmCO, and VC were decreased with age. At 90% Wpeak, DLCO, DmCO and VC were greater in Old Highly-Fit vs. Old adults. The slope of the DLCO-cardiac output (Q̇) relationship from rest to end-exercise at 90% Wpeak was not different between Young, Young Highly-Fit, Old and Old Highly-Fit (1.35 vs. 1.44 vs. 1.10 vs. 1.35 mlCO·mmHg−1·Lblood−1, P = 0.388), with no evidence of a plateau in this relationship during exercise; this was also true for DmCO-Q̇ and VC-Q̇. V̇O2max was positively correlated with: 1) DLCO, DmCO, and VC at rest; 2) the rest to end-exercise change in DLCO, DmCO, and VC. In conclusion, these data suggest that despite the age-associated deterioration in the structure and function of the pulmonary circulation, expansion of the pulmonary capillary network does not become limited during exercise in healthy individuals regardless of age or cardiorespiratory fitness level.
- Maximal aerobic capacity
- Lung diffusing capacity
- Pulmonary circulation
- Alveolar-capillary membrane conductance
- Pulmonary capillary blood volume
- Copyright © 2016, Journal of Applied Physiology