TUESDAY, Dec. 2, 2003 (HealthDayNews) -- High-intensity strength training may lead to a potentially deadly condition called aortic dissection, in which the heart's major artery tears.
That's the conclusion of new research by a team of Yale University experts that appears in the Dec. 3 issue of the Journal of the American Medical Association.
"Dissection happens in a split second," says Dr. John Elefteriades, chief of cardiothoracic surgery at Yale University and Yale-New Haven Hospital and the lead author of the report, which is contained in a letter to the journal.
In those who lift weights and already have an enlarged aorta, the elevated blood pressure that occurs during weight training may lead to the dissection, Elefteriades says.
Using a Yale database, Elefteriades and his colleagues identified five people who suffered acute dissection of the aorta during high-intensity weight training or other strenuous exercise. At the moment the dissection occurred, two of the people were weight training, one was trying to move a heavy granite structure, and two were doing pushups, the researchers say.
All were found to have an enlarged aorta, but not at a level expected to present a high risk of dissection, Elefteriades says.
Three patients who had surgical repair survived; the other two died before surgery could be attempted.
The condition of aortic dissection is "uncommon but not rare," says Elefteriades, adding that it is what killed actor John Ritter earlier this year and has been declared the cause of death of many athletes who died suddenly.
Aortic dissection strikes about two of every 10,000 people, according to the National Institutes of Health. While it can affect anyone, it's most often seen in men ages 40 to 70, the NIH says.
"We're not saying stop weight training," says Elefteriades, a long-time weight trainer himself. "It's a wonderful activity and a very important activity." It can help maintain muscle mass as you age, for instance, and help maintain strength for everyday chores such as carrying groceries.
But Elefteriades does recommend caution in certain people, including those with known aortic aneurysms -- a widening or ballooning of the vessel caused by disease or a weakening of the vessel wall. Also, those with a family history of aneurysm or dissection, underlying high blood pressure, and those at or beyond middle age should be cautious, he says, because the aorta stiffens with age. Those with connective tissue disease -- such as rheumatoid arthritis -- are also at higher risk, he says.
"I think there has to be this underlying enlargement [of the aorta] before the dissection happens," Elefteriades says.
"But we wanted to sound this warning bell that strength training and weight lifting can cause these dissections in people who already have a mild enlargement of the aorta," he adds.
The problem, Elefteriades says, is that many people with an enlargement don't know they have it. An echocardiogram -- an ultrasound evaluation of the heart -- can determine whether the aorta is enlarged, he says.
When dissection of the aorta occurs, "the aorta splits into two layers," Elefteriades says. "It splits in such a way that it becomes a double-barreled tube instead of a single-barreled one." You can quickly lose blood internally and die.
Until more research is done, what should weight lifters who may be at risk do? Avoid weight training so strenuous that your blood pressure rises excessively, Elefteriades says.
"We do know that levels of blood pressure that are high are dangerous," he says. Serious weight trainers, who often bench press 300 or 400 pounds, may get blood pressures that are dangerously elevated, even up to 370 millimeters of mercury systolic, he says. Normal systolic pressure, measured as the heart beats, is below 120; normal diastolic pressure, measured as the heart rests between beats, is below 80, Elefteriades says.
While it's difficult to pinpoint how much weight is too much, Elefteriades suggests that for upper body weight training, "above half your body weight you are starting to get into the high pressure zone. For the lower body, the legs are stronger, so you could probably lift more than half your body weight [safely]."
Serious weight trainers should consider having an echocardiogram, he says.
The other take-home advice from the report is very obvious for weight lifters or would-be weight lifters, says Dr. Craig Miller, the Doelger Professor of Cardiovascular Surgery at Stanford University Medical School.
"If they have dilation or aneurysm of the thoracic aorta or a connective tissue disorder or a family history of premature aortic catastroiphic complications, do not weight lift," Miller says.