Background-The ability of older persons to function independently is dependent largely on the maintenance of sufficient aerobic capacity and strength to perform daily activities. Although peak aerobic capacity is widely recognized to decline with age, its rate of decline has been estimated primarily from cross-sectional studies that may provide misleading, overly optimistic estimates of aging changes. Methods and Results-To determine longitudinal rate of change in aerobic capacity and the influence of age, gender, and physical activity on these changes, we performed serial measurements of peak treadmill oxygen consumption (peak V O 2 ) in 375 women and 435 men ages 21 to 87 years from the Baltimore Longitudinal Study of Aging, a community-dwelling cohort free of clinical heart disease, over a median follow-up period of 7.9 years. A linear mixed-effects regression model was used to calculate the predicted longitudinal 10-year rate of change in peak V O 2 , expressed in milliliters per minute, for each age decade from the 20s through the 70s after adjustment for self-reported leisure-time physical activity. A longitudinal decline in peak V O 2 was observed in each of the 6 age decades in both sexes; however, the rate of decline accelerated from 3% to 6% per 10 years in the 20s and 30s to Ͼ20% per 10 years in the 70s and beyond. The rate of decline for each decade was larger in men than in women from the 40s onward. Similar longitudinal rates of decline prevailed when peak V O 2 was indexed per kilogram of body weight or per kilogram of fat-free mass and in all quartiles of self-reported leisure-time physical activity. When the components of peak V O 2 were examined, the rate of longitudinal decline of the oxygen pulse (ie, the O 2 utilization per heart beat) mirrored that of peak V O 2 , whereas the longitudinal rate of heart rate decline averaged only 4% to 6% per 10 years, and accelerated only minimally with age. Conclusions-The longitudinal rate of decline in peak V O 2 in healthy adults is not constant across the age span in healthy persons, as assumed by cross-sectional studies, but accelerates markedly with each successive age decade, especially in men, regardless of physical activity habits. The accelerated rate of decline of peak aerobic capacity has substantial implications with regard to functional independence and quality of life, not only in healthy older persons, but particularly when disease-related deficits are superimposed. (Circulation. 2005;112:674-682.)

Low muscle strength is associated with mortality, presumably as a result of low muscle mass (sarcopenia) and physical inactivity. Grip strength was longitudinally collected in 1071 men over a 25-year period. Muscle mass was estimated by using 24-hour creatinine excretion and physical activity values, obtained by questionnaire. Survival analysis examined the impact of grip strength and rate of change in strength on all-cause mortality over 40 years. Lower and declining strength are associated with increased mortality, independent of physical activity and muscle mass. In men <60 years, rate of loss of strength was more important than the actual levels. In men >/=60 years, strength was more protective than the rate of loss, which persisted when muscle mass was considered. Strength and rate of change in strength contribute to the impact of sarcopenia on mortality. Although muscle mass and physical activity are important, they do not completely account for the impact of strength and changes in strength.