Ventilatory responses to exercise and CO2 after menopause in healthy women: effects of age and fitness

Abstract

The extent to which aging affects respiratory control in postmenopausal women remains relatively unknown. In a cross-sectional study of 39 postmenopausal women (50-79 years), we examined the influence of age and fitness on the ventilatory responses to hypercapnia (HCVR; +8 mmHg) and exercise (ΔV˙(E)/ΔV˙CO2) above and below the anaerobic threshold (AT). Data were analyzed using the full cohort, by age (younger postmenopausal: YPM, 50-64 years; and older postmenopausal: OPM, 65-79 years) and fitness as per our previous work (Active: V˙O2max ≥90% age-predicted values; and Sedentary: V˙O2max <90% age-predicted values). Although age did not affect the sensitivity of HCVR, Active women had significantly lower HCVR gain compared to sedentary women (Sedentary: 2.12±0.80; Active: 1.57±0.73, p=0.02). In contrast, age, but not fitness, was inversely related to ΔV˙(E)/ΔV˙CO2 above AT (YPM: 46.8±11.5; OPM: 34.8±6.9, p<0.01) which may be explained, at least in part, by age-related declines in lung function. HCVR and ΔV˙(E)/ΔV˙CO2 were not correlated.