Contribution of body composition and physical activity to age-related decline in peak V̇O₂ in men and women

We examined the contribution of variations in body composition and leisure time physical activity to the age-related decline in peak oxygen consumption (V̇O₂) in men and women. Healthy males 17-80 yr old (n = 378) and females 18-81 yr old (n = 224) were characterized for peak V̇O₂ from a treadmill test to exhaustion, fat-free mass and fat mass by underwater weighing, and leisure time physical activity. Peak V̇O₂ showed a greater absolute decline (P < 0.05) with age in males (r = -0.70, slope = -0.034 l · min^-1 · yr^{- 1}; P < 0.01) than in females (r = -0.78, slope = -0.028 l · min^-1 · yr^{- 1}; P < 0.01). After statistically controlling for differences in fat-free mass and fat mass, the decline in peak V̇O₂ was diminished in both sexes, although a greater rate of decline persisted in males (r = -0.47, slope = - 0.016 l · min^-1 · yr^-1; P < 0.01) than in females (r = -0.39, slope = - 0.009 l · min^-1 · yr^-1; P < 0.01). We found that the addition of leisure time physical activity (independent of body composition) to the regression model further attenuated the rate of decline in males (r = -0.40, slope = -0.013 l · min^-1 · yr^-1; P < 0.01) but did not alter the age- related decline in peak V̇O₂ in females (r = -0.39, slope = -0.009 l · min^-1 · yr^-1; P < 0.01). We conclude that 1) the loss of fat-free mass and the increase in adiposity contribute to the decline in peak V̇O₂ with age in men and women and 2) the decline in leisure time physical activity, independent of differences in body composition, is associated with the age- related decline in peak V̇O₂ in males but not in females.