AHA: CV benefits of exercise outweigh risks for most people
For most people, the evidence supports that regular exercise confers CV benefits, but some forms of extreme endurance exercise can be harmful to those unable to handle them, according to a scientific statement from the American Heart Association.
“The last AHA statement on exercise risk was published 13 years ago and we've had an explosion of new information on the benefits and potential risks of vigorous-to-high-intensity exercise,” Barry A. Franklin, PhD, chair of the writing committee for the statement, director of preventive cardiology and cardiac rehabilitation at Beaumont Health, Royal Oak, Michigan, and professor of internal medicine at Oakland University William Beaumont School of Medicine in Rochester, Michigan, told Healio. “The mantra has changed over the last decade or so. More and more people have adapted high-volume, high-intensity exercise training programs, maybe due to the anti-aging effects and CV benefits. The mantra increasingly is that a lot of patients feel that more is better. If I tell them three miles per day, 3 days per week is good, they may go 10 miles per day, thinking more is better. The number of people who are participating in marathons and triathlons has skyrocketed in recent years. For all those reasons, we thought that it might be very beneficial to clinicians to review the data in terms of the benefits the risks of these kinds of activities.”
CV risks of exercise
According to the statement, regular participation in vigorous exercise was associated with a decrease in exertion-related sudden cardiac death.
Moreover, the committee reported a twofold to 10-fold increase in the risk for acute MI within 1 hour of participation in vigorous exercise.
In a meta-analysis of seven studies with substantial between-study heterogeneity, the summary risk ratio for MI associated with bouts of physical exertion was 3.45 (95% CI, 2.33-5.13).
“What this review showed, and was somewhat surprising, is that high-volume, high-intensity training and competition over many years are associated with slightly higher levels of coronary artery calcium, which is a harbinger of atherosclerotic CVD,” Franklin said in an interview. “We also found a greater likelihood of the development for incident atrial fibrillation, once again, in people doing extreme amounts of exercise. Even though someone may have coronary calcium, the studies from the Cooper Clinic in Dallas and others show that at any given level of coronary calcium, the higher the physical activity or fitness the lower the incidence of CV events. Just because you have coronary calcium doesn't mean you should stop exercising. In fact, exercise appears to be highly cardioprotective.
“When it comes to AF, the data are pretty clear. Sedentary older adults have the greatest risk for developing AF. If people start to do light-to-moderate exercise, the risk of developing AF decreases substantially,” Franklin said in an interview. “However, if they get into extremes and they're doing 10, 15 or 20 miles, 3 or 4 days per week, the likelihood of developing AF seems to increase in what we call a reverse J-shaped curve. The takeaway message is that it may be possible to get too much of a good thing.”
Sudden, strenuous unaccustomed physical activity significantly increases risk for acute MI and sudden cardiac death, according to the statement. These activities include racquet sports, downhill skiing, marathon running, triathlon participation and high-intensity sports activities such as basketball. Mountaineering activities, including hiking and cross-country or downhill skiing, are also associated with elevated risk for sudden cardiac death, according to the statement.
Moreover, activities such as snow shoveling have also been associated with an increased risk for CV events, conferring rate-pressure products greater than that of maximal treadmill testing and is commonly performed by unfit individuals. Patients may also develop angina at lower rate-pressure products in colder temperatures, possibly due to cold-induced vasospasm. Snow shoveling has also been associated with ventricular arrhythmias, coronary plaque rupture, STEMI and subacute stent thrombosis, according to the statement.
Healthy physical activity
The most active and fit individuals have much lower risk for CV events and all-cause mortality compared with the general population, the authors wrote, noting that at age 50 years, life expectancy is 7 to 8 years longer in the most physically fit people compared with others.
According to the AHA press release, safety recommendations for physical activity in both fit and unfit individuals include:
- Warm up before exercise by doing the planned activity at a slower pace, to gradually increase heart rate.
- Walk on a level surface for 6 to 8 weeks, progressing to walking up hills, jogging and/or more vigorous activities, so long as no symptoms occur.
- Increase time spent on exercise incrementally from 5 to 10 minutes in the beginning, building up slowly to the desired duration.
- Lower exercise intensity when environmental conditions such as high humidity or altitude put a greater strain on the heart.
- Cool down after exercise by walking at a slower pace, allowing heart rate return to normal.
- Stop and seek medical evaluation if experiencing lightheadedness, shortness of breath, chest pain or pressure.
“The latest research suggests that 85% of all U.S. adults over the age of 50 have some form of ASCVD,” Franklin said in an interview. “The take-home message is people get in trouble with exercise when they do too much too soon, so we're really emphasizing to start a walking program; gradually progress from a 2 or 3 MPH pace to a 4 or 4.5 MPH pace, provided they remain asymptomatic. If they develop symptoms like chest discomfort, lightheadedness or palpitations, they should stop exercising and immediately seek medical review.
“Overall, the benefits outweigh the risks and as we studied, thousands of people, physically active people, have about a 50% lower overall risk for acute coronary events,” Franklin told Healio. “I love, whenever I give a talk, to quote Joseph Alpert, MD, who's the editor of American Journal of Medicine, who wrote in his famous editorial, when his patients asked him how often should they exercise, his answer was, ‘Only on the days you eat.’” – by Scott Buzby
For more information:
Barry A. Franklin, PhD, can be reached at firstname.lastname@example.org.
Disclosures: Franklin and the other authors report no relevant financial disclosures.