MONDAY, June 14, 2004 (HealthDayNews) --Exercise has long been prescribed to reduce the risk of heart disease, but an international study has found that it doesn't help everyone.
The progress of atherosclerosis, a thickening of artery walls, is not slowed by exercise for those already on cholesterol-lowering medication.
But the study, which appears in the June 15 edition of the Annals of Internal Medicine, shouldn't discourage people from exercising, the authors and other experts say.
Researchers from Finland's University of Kuopio, the University of Freiburg in Germany and Louisiana State University in the United States assigned 140 middle-aged white men living in Finland to an exercise group or a "habitual activity group."
The exercise group was instructed to work out for 45 to 60 minutes five times a week and kept an exercise diary. The habitual activity group was not told to change exercise patterns and they kept no diaries.
At the beginning of the study, men in both groups had similar fitness levels and similar thickness of the walls of the carotid arteries (in the neck). Over the six-year study, they took a bicycle exercise test annually to measure breathing fitness and had ultrasounds annually to measure thickness of the carotid artery walls.
The exercise did not slow the progression of atherosclerosis, except in a subgroup of men not on cholesterol-lowering medication, they found.
Although the results might at first glance look disappointing, they should not discourage people from exercising, said Dr. Rainer Rauramaa, the lead author of the study and a professor of exercise medicine at the University of Kuopio in Finland.
"I agree the data might, at first glance, seem disappointing," Rauramaa said. "However, if you look at the results carefully, you can easily realize that regular exercise brought a significant reduction in the progression of atherosclerosis in clinically healthy, asymptomatic men who were NOT using [cholesterol lowering drugs]." And, he added, there are more people not using these drug than are using them.
The real effect of exercise might also have been diluted, he added, because some men in the habitual activity group actually exercised, and not all men in the exercise group actually did the recommended amount of exercise.
In the study, the men who exercised did a range of workouts, including walking, jogging, cross-country skiing, swimming and cycling.
The message, Rauramaa said, is not to give up on exercise.
"To those who already exercise: continue to do so," he said. "To those not yet engaged in regular exercise: you'd better change your bad habits."
Another expert agreed that the take-home message is not to give up on exercise. Dr. Ravi Dave, a cardiologist at Santa Monica UCLA Medical Center, noted that the study had a small sample size.
"It shouldn't be a message of 'exercise is futile,'" Dave said.
Exercise can help keep your weight under control, which can reduce the risk of high blood pressure, Dave said, and thus reduce heart disease risk.
In another study in the same issue, University of Washington researchers evaluated 300 Japanese-Americans and found that fat inside the abdomen predicts who will get high blood pressure.
Those who had the largest amount of abdominal fat were more than four times as likely to have high blood pressure during the 11-year follow-up.
The results are no surprise to Dave. "We know that obesity causes hypertension," he said. "You have generalized obesity and then the truncal kind, which is more concentrated in the stomach area. Generally Asians have the truncal obesity, the second kind, which is worse."
Dave said he could use the study results to advise his patients that "if you lose two inches from your waist [and thus reduce abdominal fat] you might improve your hypertension."
To learn more about staying active at any size, visit the National Institute of Diabetes & Digestive & Kidney Diseases.