CONTRIBUTION OF BODY-COMPOSITION AND PHYSICAL-ACTIVITY TO AGE-RELATEDDECLINE IN PEAK VO2 IN MEN AND WOMEN

We examined the contribution of variations in body composition and lei sure time physical activity to the age-related decline in peak oxygen consumption (Vo(2)) in men and women. Healthy males 17-80 yr old (n = 378) and females 18-81 yr old (n = 224) were characterized for peak Vo (2) from a treadmill test to exhaustion, fat-free mass and fat mass by underwater weighing, and leisure time physical activity. Peak Vo(2) s howed 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 c ontrolling for differences in fat-free mass and fat mass, the decline in peak Vo(2) 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 act ivity (independent of body composition) to the regression model furthe r 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 i n peak Vo(2) 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 increa se in adiposity contribute to the decline in peak iio, with age in men and women and 2) the decline in leisure time physical activity, indep endent of differences in body composition, is associated with the age- related decline in peak Vo, in males but not in females.