Our purpose was to determine the relationship between habitual aerobic exercise status and the rate of decline in maximal aerobic capacity across the adult age range in women. A meta-analytic approach was used in which mean maximal oxygen consumption (VO2 max) values from female subject groups (ages 18-89 yr) were obtained from the published literature. A total of 239 subject groups from 109 studies involving 4,884 subjects met the inclusion criteria and were arbitrarily separated into sedentary (groups = 107; subjects = 2,256), active (groups = 69; subjects = 1, 717), and endurance-trained (groups = 63; subjects = 911) populations. VO2 max averaged 29.7 +/- 7.8, 38.7 +/- 9.2, and 52.0 +/- 10.5 ml . kg-1 . min-1, respectively, and was inversely related to age within each population (r = -0.82 to -0.87, all P < 0.0001). The rate of decline in VO2 max with increasing subject group age was lowest in sedentary women (-3.5 ml . kg-1 . min-1 . decade-1), greater in active women (-4.4 ml . kg-1 . min-1 . decade-1), and greatest in endurance-trained women (-6.2 ml . kg-1 . min-1 . decade-1) (all P < 0.001 vs. each other). When expressed as percent decrease from mean levels at age approximately 25 yr, the rates of decline in VO2 max were similar in the three populations (-10.0 to -10.9%/decade). There was no obvious relationship between aerobic exercise status and the rate of decline in maximal heart rate with age. The results of this cross-sectional study support the hypothesis that, in contrast to the prevailing view, the rate of decline in maximal aerobic capacity with age is greater, not smaller, in endurance-trained vs. sedentary women. The greater rate of decline in VO2 max in endurance-trained populations may be related to their higher values as young adults (baseline effect) and/or to greater age-related reductions in exercise volume; however, it does not appear to be related to a greater rate of decline in maximal heart rate with age.