Effects of an aging pulmonary system on expiratory flow limitation and dyspnoea during exercise in healthy women.

Aging related changes in pulmonary function may make older women (OW) more susceptible to expiratory flow limitation (EFL) and lead to higher dyspnoea ratings during exercise relative to young women (YW). Accordingly, the purpose of this study was to compare sensory responses and EFL susceptibility and magnitude in 8 YW (29 ± 7 years) and 8 healthy OW (64 ± 3 years) matched for percentage-predicted forced vital capacity (% predicted FVC) and % predicted forced expiratory volume in 1 s. EFL was calculated as the percent overlap between tidal flow-volume loops during maximal exercise and the maximal expiratory flow-volume (MEFV) curve. Peak oxygen consumption (V'O(2peak)) was lower in the OW compared to the YW (29.4 ± 3.6 vs. 49.1 ± 8.9 ml kg(-1) min(-1), P < 0.05) as was maximal ventilation (73.7 ± 18.4 vs. 108.7 ± 14.1 l min(-1), P < 0.05). EFL at maximal exercise was present in 2 of 8 YW and in 5 of 8 OW. There were no significant differences in the magnitude of EFL between OW (23 ± 24, range: 0-69 %EFL) and YW (9 ± 18, range: 0-46 %EFL, P = 0.21). The magnitude of EFL in OW was inversely related to % predicted FVC (r = -0.69, P = 0.06), but this relationships was not observed in the YW (r = -0.23, P = 0.59). The OW consistently reported greater dyspnoea and leg discomfort for any given absolute work rate, but not when work was expressed as a percentage of maximum. Reduced ventilatory and exercise capacities may cause OW to be more susceptible to EFL during exercise and experience greater dyspnoea relative to YW for a standardized physical task.