Cardiovascular risks of physical activity in apparently healthy individuals: risk evaluation for exercise clearance and prescription

Exercise-induced cardiovascular (CV) events, particularly sudden cardiac death (SCD), attract considerable media attention in the context of the safety of exercise for the general population. As a result, concern about the safety of exercise participation is a common topic during routine office checkups and with the prescribed recommendation of increased physical activity (PA). In reality, it is estimated that only 4% to 17% of myocardial infarctions in men are linked to physical exertion, with much lower rates observed for women.1,2 Of these exercise-related events, it is also true that few occur in the absence of preexisting cardiovascular disease (CVD), for which risk factors might (or might not) have already been evident. This article provides an executive summary of findings from a systematic review of the risks of PA in apparently healthy individuals.3 It is one in a comprehensive series of reviews examining the risks of PA in healthy individuals and patients with various chronic diseases. The evidence thus obtained provides the foundation for new tools that will simplify the tasks of exercise clearance and prescription: the revised Physical Activity Readiness Questionnaire (PAR-Q+) and the electronic Physical Activity Readiness Medical Examination (ePARmed-X+) procedure.4 We present background evidence and mechanistic pathways regarding the risks of exercise in apparently healthy patients. The intention of this article is to facilitate the family physician's tasks of screening patients for PA participation and providing risk-appropriate PA prescriptions. Growing evidence indicates that a range of PA confers some benefit in a dose-response pattern, demonstrating a continuum of increasing benefit and risk reduction as one progresses from low-intensity to more vigorous PA. In healthy individuals, low-intensity exercise performed regularly (3 to 5 times per week) can elicit substantial improvements in measures of quality of life, body composition, and CVD risk factors. More vigorous PA has been associated with pronounced reductions in risk and all-cause mortality rates in individuals with various chronic diseases. Energy expenditure through vigorous PA of at least 1000 kcal per week, but optimally closer to 2000 kcal per week, has yielded the greatest risk reductions for CVD.5,6