Aerobic exercise, resistance training and both together safely improved endothelial function after myocardial infarction, but quitting training quickly caused the improvements to lapse, according to a study reported in Circulation: Journal of the American Heart Association.

"While it is generally accepted that exercise training for people with coronary artery disease improves vascular function, controversy still exists regarding the right level and right format of exercise," said Margherita Vona, M.D., lead author of the study and a cardiologist and director of the Cardiac Rehabilitation Center, Clinique Valmont-Genolier in Glion sur Montreux, Switzerland.

Researchers assessed the effect of different types of exercise, as well as the effect of stopping exercise in 209 people who'd had heart attacks. They measured participants' endothelial function at the start of the study and after four weeks of training. Participants then quit their training for one month and researchers measured blood vessel function again.

The researchers randomly assigned the patients to receive aerobic training, resistance training, aerobic and resistance training combined, or no training:

• The aerobics participants underwent moderate training four times a week for a month. Each session included a 10-minute warm-up, 40 minutes of cycling at an intensity of 75 percent of maximum heart rate and a 10-minute cool-down.
• The resistance training group did four sets of 10 resistance exercises repeated 10-12 times, for a total of 40 exercises four times a week for four weeks - a controlled, moderate-intensity training as recommended by the American Heart Association's guidelines for resistance training.
• The combined group alternated controlled resistance and controlled aerobic training sessions.

The endothelial function of those in the three exercise groups improved after four weeks of exercise, regardless of the type of exercise, researchers said. The endothelial function on the non-exercising group, however, did not improve significantly.

Researchers used flow-mediated dilation (FMD) to measure blood vessel function.

After one month of training, FMD increased from about 4 percent before the exercise programs, to about 10 percent (which is normal function) in trained patients. Researchers found no significant change in the non-training group (FMD increased from 4.3 percent to 5.1 percent).

However, after one month of detraining, or stopping regular exercise, all the positive effects on endothelial function were lost. Thus, long-term adherence to training programs is necessary to maintain vascular benefits on endothelial function, Vona said.

"This aspect is particularly important in patients with coronary artery disease, in whom the correction of endothelial dysfunction could help to slow the progression of atherosclerosis and probably avoid subsequent heart attacks," she said. "All the types of exercise were well tolerated and did not cause any complications in our patients.

"This should be an additional reason to encourage patients to carry out several types of physical activity to avoid exercise boredom and promote better long-term adherence to exercise programs."

The study was funded by Clinique Valmont-Genolier.

Co-authors are: G.M. Codeluppi, M.D.; T. Iannino, M.D.; E. Ferrari M.D.; J. Bogousslavski, M.D.; and L. von Segesser, M.D.