Nov. 14, 2000 (New Orleans) -- Before you work out -- or pig out -- be forewarned: If you normally spend more time on the sofa than the Stairmaster, you could be setting yourself up for a deadly heart attack or stroke. New research shows that sedentary individuals are much more likely to die suddenly after eating a heavy meal or exercising vigorously. But before you use these latest research findings as another excuse to skip the gym, bear in mind that regular, moderate exercise is still what experts advise.
In a study that lasted four years, Francisco Lopez-Jimenez, MD, MSc, and colleagues at Brigham and Women's Hospital in Boston, conducted in-depth interviews with nearly 2,000 patients, within a few days of their hospitalization for a heart attack. "We found that patients who'd had what they described themselves as an unusually large meal were more likely to have a heart attack. This basically confirms the popular belief that a very large meal may start the process," he tells WebMD.
So just how risky is that belt-busting Thanksgiving dinner? "The [risk is] probably similar to that of sexual activity," says Lopez-Jimenez -- real, but "not tremendous." Still, he says, "this is important now, because restaurant meals are getting bigger and bigger." What people begin to see as a normal amount of food could actually be dangerous.
According to Lopez-Jimenez, the risk could be due to the effects of fat on the cells that line our arteries, or perhaps the rush of hormones released into the bloodstream during digestion. "It's similar to what happens during heavy exercise," he explains. Also, the sharp rise in blood sugar levels after a big meal can change the way arteries function, he says. This is especially important in women dieters, who tend to skip breakfast and lunch and then "binge" on a too-large dinner, potentially putting themselves at risk.
Whatever the mechanism, "the findings open a whole new research area," says Lopez-Jimenez, who presented his findings here Tuesday at a meeting of the American Heart Association. Future work, he says, will investigate specific foods, timing of meals, and other factors that could affect risk.
"As with many things in life, moderation is the key," Lopez-Jimenez tells WebMD. "Those people with a history of heart disease, or with risk factors such as diabetes or smoking, really need to watch the size of meals, not only the content."
A similar message of moderation -- this time for exercise -- can be taken from two other studies. "The risk of exercise -- meaning the risk of dying during or immediately after exercise -- is very low," says Barry Franklin, MD, director of cardiac rehabilitation at William Beaumont Hospital in Royal Oak, Mich. "It's the infrequent exerciser -- the one who decides to go out and get all their exercise in one day -- who's at the greatest risk." That is, the "perfectly healthy guy" who drops dead without warning while shoveling his driveway or after eating a big holiday meal was almost certainly overweight, sedentary, and already well on his way to that heart attack.
Franklin and colleagues collaborated with Bally's Total Fitness health clubs to determine just how often people die during or just after working out, and who's most likely to do so. "When you walk into one of these clubs, your membership card is swiped. That provides a record of the number of visits for each member," he says. They analyzed the records at 320 clubs, where "between 1997 and 1998, there were approximately 182 million visits made by 3 million members."
In all, 61 men and 10 women had died at the clubs; the victims were an average of 53 years old. "That translates to one death out of every 2.57 million workouts," Franklin says. "This study indicates that among the general population, at least among members of commercial fitness facilities, the risk is extremely low."
When they looked more closely at precisely who had died and why, they found that "a third had a history of cardiovascular disease or known risk factors." Half had exercised less than once, and three-quarters less than twice per week in the months prior to dying. In fact, only three had been regular exercisers who hit the gym five times each week. "More than half of the people who died were engaged in some sort of aerobic exercise -- probably extremely vigorous -- when they died," Franklin says.
But, he says, "this does not mean that aerobic exercise is dangerous. The public needs to increase the regularity of their workouts to get benefits and reduce their risk of a cardiovascular event." If you simply can't find a way to bump up your frequency, he says, "don't go in there and turn the treadmill up to 8 mph. Sporadic exercisers should adopt a mild to moderate pace."
In another study, Gerald Fletcher, MD, and colleagues found that this kind of regular exercise -- five sessions per week -- can even help men who've already had a heart attack or undergone surgery to treat blocked arteries. "After 6 months, we saw a significant increase in HDL -- the good cholesterol -- regardless of workout intensity," he says, and there's no reason to believe the findings would be any different in women.
Fletcher, who is a cardiologist and professor of medicine at the Mayo Clinic in Jacksonville, Fla., believes in practicing what he preaches. He runs about 14 miles per week, on the beach or the road, at a rate of 10-12 minutes per mile.
"Overall, if you look at all the factors, the fact is that physically active people have half the risk of coronary artery disease as their sedentary counterparts," Franklin says. "The main message is that the benefit of exercise far outweighs the risk." He himself walks about 12 miles a week with his wife and dog, usually in one-hour stints, and also does some resistance training (such as lifting weights) twice a week.
Fletcher agrees. "We want to let the public know that any exercise you do is beneficial, including low-level activity," he says. "We're beginning to think that frequency, not duration or intensity, is most important."