“To our knowledge, this analysis is the first to assess both the transient and long-term risk of sudden cardiac death associated with physical activity among women,” says Albert, senior author of the study and also director of the Center for Arrhythmia Prevention at the Harvard-affiliated Brigham and Women’s Hospital in Boston. Results of the study appear in the March 22/29 Journal of the American Medical Association’s theme issue on Women’s Health.

The findings are encouraging. Out of almost 85,000 women, only nine died while doing yard work, housework, swimming, or physical therapy. To put this in numbers, as scientists always like to do: Their investigation covered 1.93 million person years of exercise and recorded only one death for each 36.5 million hours of exertion. In other words: Sudden cardiac death during exertion is an extremely rare event in women.

And there’s still more good news. Regular exercise may significantly minimize this small risk, in both the short and long term. “The women who reported exercising four or more hours a week had a 59 percent lower risk of sudden cardiac death over 18 years of follow-up compared to women who reported not exercising at all,” notes William Whang, lead author of the study and a fellow at Massachusetts General Hospital. “Also, women who exercised two or more hours a week had no elevated risk of sudden cardiac death during exertion. This risk appeared to be primarily limited to inactive women.”

“It was not surprising that the absolute risk of sudden cardiac death with moderate-to-vigorous exercise was extremely low in women,” comments JoAnn Manson, a professor of women’s health at Harvard who participated in the research. “However, it was surprising that regular exercise had such a powerful role in reducing the long-term risk of sudden death. Regular exercise is truly a ‘magic bullet’ for good health.”

Women in this study were more than 34 years old; would the results also apply to younger women? “Most likely,” says Manson, who is also head of the Division of Preventive Medicine at Brigham and Women’s Hospital. “The biological relationships are likely to hold for younger women as well. However, younger women have exceedingly low risks of sudden cardiac death.

“It’s likely that the key factor for all women, regardless of age, would be their habitual exercise level,” she continues. “Women who are regularly active would be able to tolerate vigorous exercise much better than women who are habitually sedentary, whatever their age.”

No matter how high the risk rises, however, it will probably be less than for men who exercise vigorously.

This is likely related to the heart protection women enjoy from their natural hormones during the years before menopause, Manson believes. “After menopause women gradually catch up with men but the gender gap for heart and blood vessel diseases can be substantial,” she says.

An earlier analysis of male physicians done by Albert, Manson and colleagues found that men’s risk of sudden cardiac death during vigorous exertion was 19 times higher that that of women. However, like women in the study, the most active men enjoyed the lowest risk of sudden death during exertion.

Part of the difference, Albert notes, could be due to including both moderate and intense exercises in the women’s study but only vigorous exertion in the male analysis. But that’s not the whole story. Similar sex differences show up in smaller studies of men in both the United States and Finland. In these latter studies, the same measures of exercise showed a nine- to 14-fold higher risk for men. To date, this apparent sex difference remains unexplained.

The final conclusions of the women’s study probably apply to men: Moderate and vigorous exercise can be done safely and, if performed regularly, may lower the long-term risk of sudden cardiac death.

— Source: Harvard News Office

Comments From Jon…

It is crucial to understand the context and the scope of this study. First, the conclusions in the final paragraph really sum up the findings fairly accurately — that moderate or even vigorous regular exercise may (more than likely “will”) reduce sudden death risk from coronary events. But this is only part of the story. The rest of the story needs to be addressed, and hopefully Harvard will do just that.

First, the cases of sudden death in gym-related exercise conditions is very low. Far more people (men and women) die of heart attacks during their sleep or driving, and no one seems to be protesting sleep or travel. This is where statistics can be deceiving.

Someone who has a fatal coronary event during exercise is someone who “would” have had the event within weeks, days or even hours, no matter what. This is the conclusion of multiple cardiologists, and a bit of common sense at that. The heart was designed to pump and work hard. Only those with known heart conditions are at risk of overdoing exercise. Even heart attack survivors work out harder than the average person — this has been documented in several studies. Most cardiologists would say this is a good thing!

So, we take someone who is already a walking time-bomb and put them in the gym. Of course “vigorous” training could have harmful consequences. Then again, so can (and does) sex, yardwork, and other daily activities. While someone “could” push hard enough to cause a coronary event in the gym, the odds are much higher that they would demonstrate symptoms of heart failure well prior to a gut-busting set of squats.

Many people ignore the obvious warning signs, such as shortness of breath (not from a temporary oxygen debt, as in cardio work, but during a non-working state), chest pain, etc.

Finally, just a commentary on the “unknown male variable”. Again, I feel this is common sense — men are stubborn! We tend to push through pain and ignore it, often to our detriment. This, along with the fact that men tend to overdo physical exercise as a display of being “macho”, probably contributes greatly to the statistical increase in fatal coronary events during exercise.

Training the way we suggest in Fit Over 40 will increase your odds of not having to face this scenario to begin with. Exercise prevents thousands of heart attacks for every one that is attributed to it. Combined with proper nutrition, another key variable missed by the Harvard study, the odds of dying during exercise of moderate to vigorous activity decreases exponentially.

Please be sure to consult with your physician prior to undertaking any strenuous activity — that includes yardwork, sex, and hitting the weights. It’s best to rule out any conditions prior, but by all means do not be deceived into thinking that rest is superior to exercise for the vast majority of males or females at any age and in almost any state of present health.

[jB]