Dying during or immediately after physical activity occurs rarely. But the exercise-related death of a prominent Wall Street executive last week nevertheless raises concerns for people who want to keep active during middle age and later years.

Regular exercise is a cornerstone of good health, and its long-term benefits for both longevity and protection against heart attacks, cancer and other ailments are supported in many studies. Doctors say there are strategies to reduce the already low likelihood of a workout turning into a tragedy.

James B. Lee Jr., the 62-year-old vice chairman of J.P. Morgan Chase & Co., who regularly exercised, became short of breath while exercising and went to a hospital, where he died, his company has said. No further details have been provided. Such events could result from an aortic aneurysm or another cause, but they typically raise questions about a heart condition.

“Exercise is not a vaccine against heart disease,” says Michael Joyner, an exercise physiologist at Mayo Clinic, in Rochester, Minn. While not specifically addressing Mr. Lee’s case, Dr. Joyner noted that risk factors such as high blood pressure and high cholesterol are increasingly common as people age.

“You need to get them treated,” he says. “Middle-aged men in high-stress jobs need to get a checkup once in a while.”

Growing numbers of people are moving through middle age determined to stay active with competitive sports and regular exercise. Doctors urge others who are on the sidelines to join in to improve their health. But high-profile events such as Mr. Lee’s death may stir anxiety. Researchers say not to worry.

“There is unequivocal evidence that regular physical activity and exercise have multiple benefits that far outweigh any risk of the exercise itself,” says Jonathan A. Drezner, director of the Center for Sports Cardiology at the University of Washington, in Seattle.

But, while a person is doing it, rigorous exercise, whether on a treadmill, a road race or a basketball court, does elevate risk for sudden cardiac arrest, a typically fatal event that can be triggered by a heart attack but is the immediate result of an out-of-control arrhythmia that causes the heart to stop beating.

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