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

We investigated the hemodynamic determinants of the age-associated decline in maximal oxygen uptake (<(V)over dot > O-2 (max)) and the influence of gender on the decline in <(V)over dot > O-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 <(V)over dot > O-2 (max) and maximal cardiac output (<(Q)>(max)) were determined. <(V)over dot > O-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 <(V)over dot > O-2 (max) vs. age relationship was twofold steeper in men than in women (P < 0.0001). <(Q)over dot >(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-vDO(2)) 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 <(Q)over dot >(max) and a-vDO(2) contributed equally to the declines in <(V)over dot > O-2 (max) in both men and women. In the later stages of life, <(V)over dot > O-2 (max), <(Q)over dot >(max), and a-vDO(2) 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 <(Q)over dot >(max) and a-vDO(2) contribute equally to the age-related decrease in <(V)over dot > O-2 max in men and women.