A new study adds a new twist to the "no pain, no gain" theory by finding that increased intensity of exercise significantly lowers the risk of coronary heart disease (CHD) in men. The research appears in tomorrow's Journal of the American Medical Association.
"We all know that physical activity is good for heart disease. This is the first time we've shown that intensity of exercise over and above the amount of energy expenditure makes a difference," says Dr. Frank Hu, senior author of the study and an associate professor of nutrition at Harvard School of Public Health. "If the exercise is suitable for the person, I think people should aim for more rigorous exercise given the amount of energy expenditure."
In other words, if you can burn 100 calories either by walking for an hour or running for half an hour, go for the run.
The association between aerobic activity and reduced risk for CHD was expected. More surprising were results documenting a similar risk reduction with weight training. "This is the first study to directly look at the relationship between weight training and risk of CHD, and this is the first evidence that resistance training is beneficial for heart disease," Hu says.
The study looked at a group of 44,452 male dentists, optometrists, pharmacists, podiatrists, osteopaths and veterinarians enrolled in the Health Professionals' Follow-up Study who were interviewed at two-year intervals between 1986 and the beginning of 1998.
Men who ran for an hour or more each week had a 42 percent reduced risk for CHD compared with men who did not run. Men who trained with weights for 30 minutes or more per week had a 23 percent reduced risk of CHD compared with those who did not. Rowing for one hour or more per week was associated with an 18 percent reduced risk. A half-hour or more of brisk walking each day was also associated with an 18 percent reduction in risk for CHD. The faster you walked, the bigger the reduction.
Moreover, Hu says, "men who exercised one hour per day had a 30 percent lower risk compared with those who exercised one hour per week. This is an overall estimate and does not consider types and intensity of exercise."
The physically active men in the study also tended to have lower body mass indexes, lower total fat intake, higher intakes of fiber and alcohol, and lower incidences of smoking and high blood pressure.
"This certainly demonstrated the enormous potential for exercise in lowering the risk of heart disease," Hu says.
Aerobic activity, we know, has a direct effect on heart muscle, can raise "good" and lower "bad" cholesterol, and can lower blood pressure. Weight training does not have a direct effect on the muscles of the heart, but it can have a beneficial effect on insulin resistance and body fat, which in turn can have an effect on heart disease.
The value of a study such as this is how it is used to fight the "epidemic of sloth" in America, says Dr. Alan Rozanski, director of nuclear cardiology and cardiac stress testing at St. Luke's-Roosevelt Hospital and a professor of medicine at Columbia University College of Physicians and Surgeons, both in New York City. "On a societal level, we have to start a process where we're getting the message out. The problem today is intellectually people understand that exercise is useful but, given our lifestyles and the combination of forces within our society, we need to translate this into action."
Current exercise recommendations emphasize moderately intense activities such as walking and don't highlight weight training. "Our results suggest that resistance training can be incorporated in combination with aerobic exercise," Hu says.
Rozanski thinks things need to be even simpler than that: "Take the stairs instead of the elevator and carry the groceries instead of paying someone to do it. The other way is so convenient. You think, 'I'll save a few minutes here, a few minutes there,' but you're literally going to lose, days, months, minutes of your life."
What To Do
For more on your heart and exercise, visit the American Heart Association's Personal Fitness Center. You could also try HealthierUS.