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

Abstract

Studies assessing changes in maximal aerobic capacity (V˙o 2 max) associated with aging have traditionally employed the ratio ofV˙o 2 max 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 inV˙o 2 max 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 inV˙o 2 max and satisfied all the important general linear model assumptions. The other approaches failed to satisfy one or more of these assumptions. The results indicated thatV˙o 2 max declines at the same rate in athletic and sedentary men (0.24 l/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.