Feb. 26 (UPI) -- Slow and steady wins the race -- at least when it comes to exercise for heart health, the American Heart Association said Wednesday.
In a scientific statement published in Circulation, an AHA team of experts noted that while aerobic exercise generally benefits health, more intense physical activities -- like marathons and triathlons -- can raise a person's risk for sudden cardiac arrest, atrial fribrillation and heart attack.
The findings are based on analysis of more than 300 scientific studies.
"Exercise is medicine, and there is no question that moderate to vigorous physical activity is beneficial to overall cardiovascular health," Barry A. Franklin, chairman of the AHA committee that drafted the statement and director of preventive cardiology and cardiac rehabilitation at Beaumont Health in Royal Oak, Mich., said in a press release. "However, like medicine, it is possible to under-dose and overdose on exercise. More is not always better."
In a review of research, the researchers found that, for the most people, the benefits of exercise outweigh the risks. Physically active people, such as regular walkers, have up to a 50 percent lower risk of heart attack and sudden cardiac death than those who lead more sedentary lifestyles.
However, the researchers reviewed a small study that found that, while the risk of sudden cardiac death or heart attack is generally low among people participating in marathons and triathlons and other similar activities, over time the risk increases, particularly among men. This indicates that these events may be attracting higher-risk participants -- including those who may have an underlying or undiagnosed cardiovascular condition such as heart rhythm abnormalities, the researchers said.
For women, who comprised only 15 percent of the study population, the occurrence of sudden cardiac death was 3.5-fold less than in men.
Almost 40 percent of cardiac events in triathlon participants occurred in first-time participants, indicating that inadequate training or underlying heart problems may be involved.
"More people are running marathons, participating in triathlons and doing high-intensity interval training," Franklin said. "The purpose of this statement is to put the benefits and risks of these vigorous exercise programs in perspective."
For people who want to become more active, the AHA recommends starting a light program of exercise and building up slowly to a moderate to vigorous exercise regimen. Good aerobic exercise activities for heart health include walking, running, bicycling and swimming.
For those who are inactive or sedentary, the AHA also suggests checking with a doctor before engaging in strenuous activities such as shoveling snow or racquet sports, which can cause rapid increases in heart rate and blood pressure.
In addition, people with known heart disease should get their doctor's approval prior to starting an exercise program.
"It is important to start exercising -- but go slow, even if you were an athlete in high school," Franklin said.