From the Guidelines
Excessive physical activity can indeed cause cardiac stress, particularly in individuals with underlying genetic heart diseases, as it may trigger malignant ventricular arrhythmias leading to cardiac arrest and sudden cardiac death. While regular moderate exercise is beneficial for heart health, high-intensity and competitive exercise can pose significant risks, especially for those with conditions such as hypertrophic cardiomyopathy (HCM) or arrhythmogenic right ventricular cardiomyopathy (ARVC) 1. The risk of sudden cardiac death (SCD) during exercise is higher in athletes compared to non-athletes, with studies suggesting a 2-fold to 7-fold increased risk depending on the population and intensity of exercise 1.
Key factors contributing to this risk include the presence of underlying cardiac conditions, high-intensity exercise, and individual genetic predispositions. For instance, mutations in cardiac potassium ion channels, such as those found in LQT1, can confer a higher risk of cardiac arrest during exercise due to abnormal potassium currents in the heart 1. Physiological changes induced by exercise, including increased catecholamine levels, acidosis, dehydration, and electrolyte imbalance, can act as triggers for arrhythmias in susceptible individuals 1.
To mitigate these risks, it is essential for individuals, especially those with known or suspected genetic heart diseases, to undergo thorough medical evaluations before engaging in high-intensity or competitive sports. Athletes and individuals pursuing intense training should adhere to guidelines that include gradual build-up of exercise intensity, incorporation of rest days, proper hydration, and awareness of body warning signs such as chest pain or irregular heartbeats. For the general population, following established exercise guidelines, such as 150 minutes of moderate exercise or 75 minutes of vigorous exercise weekly, is recommended while being mindful of the J-curve relationship between exercise and cardiac health, where both inactivity and extreme exercise may increase cardiac risks 1.
From the Research
Cardiac Stress and Excessive Physical Activity
- Excessive physical activity can cause cardiac stress, as evident from studies that suggest a possible cardiotoxic effect of intense exercise 2.
- Chronic, excessive sustained endurance exercise may lead to adverse structural remodeling of the heart and large arteries, including transient acute volume overload of the atria and right ventricle, and elevations of cardiac biomarkers 3.
- High-intensity endurance exercise has been associated with cardiac dysfunction, including increased cardiac remodeling, myocardial fibrosis, and arrhythmias 4.
Risks and Benefits of Exercise
- Regular exercise decreases the burden of cardiovascular risk factors and improves prognosis in several cardiac conditions, making it safe for the majority, even with cardiovascular disease 2.
- However, sudden cardiac death during sports may occur in apparently healthy athletes who perform at the highest levels, highlighting the need for accurate identification and prompt treatment of individuals at risk 2.
- Moderate exercise has been shown to be beneficial in chronic stable heart failure, but competitive sports are contraindicated in most forms of hypertrophic cardiomyopathy, myocarditis, pericarditis, and right ventricular cardiomyopathy/dysplasia 5.
Exercise Recommendations and Precautions
- Prescreening on an individual basis should be considered for leisure sports, particularly in people who decide to start training in middle age after years of physical inactivity to regain physical fitness 5.
- Individuals participating in extreme forms of endurance sports should be aware that high-intensity endurance sports can lead to structural alterations of the heart muscle even in healthy individuals 5.
- Maintaining physical fitness through regular physical activity may help to reduce exercise-related acute cardiovascular events, and strategies such as screening patients before participation in exercise and excluding high-risk patients from certain activities appear prudent 6.