BACKGROUND: Official guidelines from the
Centers for Disease Control and Prevention and the
American College of Sports Medicine state that every adult should accumulate 30 minutes or more of moderate-intensity
physical activity on most, preferably all, days of the week. OBJECTIVE: To examine the dose-response relationship between
coronary heart disease (
CHD)
risk factors and vigorous
exercise above the recommended
minimum levels to assess whether further benefits accrue. METHODS: Physician-supplied medical data were compared with reported distance run in a national
cross-sectional survey of 8283 male recreational runners. RESULTS: Compared with runners who ran less than 16
km (10 miles) per week, long-distance runners (> or = 80
km/wk) showed an 85% reduced prevalence of
high-density lipoprotein cholesterol levels that were clinically low (< 0.9
mmol/L [< 35
mg/dL]), a 2.5-fold increased prevalence of clinically defined high levels of
high-density lipoprotein cholesterol (ie, > or = 1.55
mmol/L [> or = 60
mg/dL], the level thought to be protective against
CHD), a nearly 50% reduction in
hypertension, and more than a 50% reduction in the use of medications to lower
blood pressure and
plasma cholesterol levels. Estimated age-adjusted 10-year
CHD risk was 30% lower in runners who averaged more than 64
km/wk than in those who averaged less than 16
km/wk (42 vs 61 events per 1000 men). Each 16-
km incremental increase in weekly distance run up to 64 to 79
km/wk was associated with significant increases in
high-density lipoprotein cholesterol levels and significant decreases in
adiposity,
triglyceride levels, the
ratio of
total cholesterol to
high-density lipoprotein cholesterol level, and estimated
CHD risk. CONCLUSIONS: Our data (1) suggest that substantial health benefits occur at
exercise levels that exceed current
minimum guidelines and (2) do not exhibit a point of diminishing return to the health benefits of
running at any distance less than 80
km/wk.