Abstract

Numerous studies support the preventive role of regular moderate-to-vigorous physical activity (PA) and increased cardiorespiratory fitness (CRF) on varied chronic diseases, including cardiovascular disease (CVD). Individuals with low levels of CRF have higher health care costs, higher rates of incident heart failure, and increased cardiovascular events at any given coronary artery calcification (CAC) level and are more likely to die prematurely than their risk factor–matched counterparts. Furthermore, increased levels of PA and/or CRF before hospitalization for acute coronary syndrome or elective or emergent surgical procedures appear to confer more favourable short-term outcomes. The cardioprotective benefits of regular PA, increased CRF, or both are attributed to multiple mechanisms, including anti-atherosclerotic, anti-ischemic, anti-arrhythmic, anti-thrombotic, and improved psychologic effects. Biochemical cardiac pre-conditioning against ischemic damage also has a significant prophylactic role. Although vigorous exercise is more cardioprotective, it is also associated with a higher incidence of acute cardiac events, especially when it is unaccustomed and performed by individuals with known or occult CVD. Nevertheless, there are recurrent reports of trained individuals who experience acute myocardial infarction and/or sudden cardiac death during endurance events like marathons and triathlons who, at autopsy, had underlying atherosclerotic CVD or structural cardiovascular abnormalities. In addition, emerging evidence from epidemiologic studies and observational reports now suggest that potentially adverse cardiovascular manifestations may occur in some endurance athletes following high-volume and/or high-intensity long-term exercise training, especially accelerated CAC and incident atrial fibrillation (i.e., in a reverse J-shaped curve). Despite such caveats, the benefits associated with regular physical activity far outweigh the risks. Because physical inactivity, attributed in part to contemporary technologic advances, now represents a worldwide pandemic, additional interventions are urgently needed to increase population levels of PA.