Does Self-Reported Physical Activity Underestimate the Importance of Activity in Cardiovascular Disease Prevention?

Abstract

Engagement in regular exercise or physical activity (PA) is known to protect against cardiovascular disease. Evidence for this strong association comes from both epidemiologic studies in which individuals self-report their level of PA and randomized controlled trials in which individuals increase their level of PA to a pre-defined level for a specific duration. Misclassification biases associated with self-reported PA may underestimate the true reduction in cardiovascular disease (CVD) risk obtained through regular engagement in PA, particularly at high levels. Given the strong dose–response relationship observed between objectively measured PA and changes in CVD risk factors in randomized controlled trials, the estimated risk reduction associated with high levels of PA (> 2,000 kcal/wk) would be predicted to be larger than current estimates (30% risk reduction) derived from epidemiologic studies. Self-reported PA may underestimate the true risk reduction in CVD produced through engagement in high levels of PA, although definitive evidence is not available.