Physical Activity and Cardiovascular Disease: How Much is Enough?

Abstract

Physical inactivity is an established risk factor for cardiovascular diseases. However, while physical activity is recommended as a component of healthy lifestyle, the amount (intensity, duration and frequency) of physical activity required to protect against coronary heart disease (CHD) and cerebrovascular disease (i.e., stroke) is unclear. In general, there is a graded inverse association of physical activity with CHD and total cardiovascular disease (the combination of CHD and stroke). The patterns of association between physical activity dose and stroke are less clear; individual studies suggest a threshold effect for benefits, while meta-analytic studies report a graded inverse association. Despite known differences in physical activity behaviors between men and women, the patterns of association between dose of activity and cardiovascular diseases are similar by gender. Observational studies of walking behaviors and one recent clinical trial suggest that lower "doses" of physical activity are associated with a lower risk of cardiovascular disease. Thus, with very few specific cautions, there is enough evidence to recommend to healthy adults that any activity is beneficial and that more activity is even better.

Figure 1

Meta-Analytic results of the association between physical activity dose-response and cardiovascular disease in 3 prospective studies of women

Figure 2

Crude Rates and Adjusted Relative Risks (95% Confidence Intervals) for CHD by weekly MET-hours of physical activity, Health Professionals Follow-Up Study. The median value and range MET-hour/week are as follows: Q1=1.2 (0-2.9); Q2=5.0 (3.0-7.9); Q3=12.1 (8.0-17.7); Q4=24.1 (17.8-34.5); Q5=49.1 (34.6-69.2).