Accelerated decline of aerobic fitness with healthy aging: what is the good news?

As we get older, even if we are healthy, we become less fit. At the extreme, we become disabled and eventually die. Although this deterioration in physical work capacity is widely accepted, few studies have characterized changes in aerobic capacity across the age span. Instead, the majority of studies have utilized cross-sectional designs. These studies are limited, however, by selective survival—ie, older participants, as a group, are inherently healthier than younger individuals, as evidenced by their survival. Thus, the 5% to 10% drop in aerobic fitness per decade, defined from cross-sectional studies, may well be an underestimate.1–6