Gender differences in the decline in aerobic capacity and its physiological determinants during the later decades of life

Abstract

We investigated the hemodynamic determinants of the age-associated decline in maximal oxygen uptake (V̇o_{2 max}) and the influence of gender on the decline in V̇o_{2 max} and its determinants in old and very old men and women. Sedentary, 60- to 92-yr-old women ( n = 71) and men ( n = 29), with no evidence of cardiovascular disease, underwent maximal treadmill exercise tests during which V̇o_{2 max} and maximal cardiac output (Q̇_max) were determined. V̇o_{2 max} and age were inversely related in both women (−23 ± 2 ml·min⁻¹·yr⁻¹; P < 0.0001) and men (−57 ± 5 ml·min⁻¹·yr⁻¹; P < 0.0001). The absolute slope of the V̇o_{2 max} vs. age relationship was twofold steeper in men than in women ( P < 0.0001). Q̇_max was also inversely related to age in a gender-specific manner (women = −87 ± 25 ml·min⁻¹·yr⁻¹, P = 0.0009; men = −215 ± 50 ml·min⁻¹·yr⁻¹, P = 0.0002; P = 0.01 women vs. men). Age-related changes in maximal exercise arteriovenous oxygen content difference (a-vDo₂) were marginally different ( P = 0.08) between women (−0.12 ± 0.03 ml·dl⁻¹·yr⁻¹, P = 0.0003) and men (−0.22 ± 0.04 ml·dl⁻¹·yr⁻¹, P < 0.0001). Age-associated decreases in Q̇_max and a-vDo₂ contributed equally to the declines in V̇o_{2 max} in both men and women. In the later stages of life, V̇o_{2 max}, Q̇_max, and a-vDo₂ decrease with age more rapidly in older men than they do in older women. As a result, the gender differences dissipate in the later decades of life. Declines in Q̇_max and a-vDo₂ contribute equally to the age-related decrease in V̇o_{2 max} in men and women.