Editorial

Physical inactivity is a serious health problem worldwide, con-tributing to early development of obesity, diabetes mellitus, hypertension, and cardiovascular diseases (CVD).1 In fact, our hypokinetic lifestyle is now widely recognized among the most proximal risk factors for heart disease (Figure 1), along with poor dietary habits and cigarette smoking.2–4 To address these concerns, public health strategies commonly incorporate the goal of safely increasing physical activity levels in the populations of industrial-ized societies. Accordingly, the number of health/fitness facilities and members is expected to increase exponentially over the next decade. Current market research indicates that the fastest-growing user subsets are those aged 35 to 54 years and those ≥55 years of age. These data, coupled with the recent finding that regular exer-cise prevents cellular senescence, have led an increasing number of adults, many of whom have known or occult chronic disease, to the conclusion that “more exercise is better. ” Marathon running