Predictors of age-associated decline in maximal aerobic capacity: A comparison of four statistical models

Abstract

Studies assessing changes in maximal aerobic capacity (V̇O(2max)) associated with aging have traditionally employed the ratio of V̇O(2max) to body weight. Log-linear, ordinary least-squares, and weighted least-squares models may avoid some of the inherent weaknesses associated with the use of ratios. In this study we used four different methods to examine the age- associated decline in V̇O(2max) in a cross- sectional sample of 276 healthy men, aged 45-80 yr. Sixty-one of the men were aerobically trained athletes, and the remainder were sedentary. The model that accounted for the largest proportion of variance was a weighted least-squares model that included age, fat-free mass, and an indicator variable denoting exercise training status. The model accounted for 66% of the variance in V̇O(2max) and satisfied all the important general linear model assumptions. The other approaches failed to satisfy one or more of these assumptions. The results indicated that V̇O(2max) declines at the same rate in athletic and sedentary men (0.24 1/min or 9%/decade) and that 35% of this decline (0.08 l · min-1 · decade-1) is due to the age-associated loss of fat-free mass.