Exercise improves blood vessel function after myocardial infarction—but only as long as the patient sticks with it. In a recent study, the positive effect on endothelial activity disappeared four weeks after the workout routine was discontinued (Circulation. 2009;119:1601-1608).

Researchers evaluated 209 heart-attack patients who were subsequently assigned to one of four groups: (1) Aerobic training (moderate training four times a week: a 10-minute warm-up, 40 minutes of cycling at 75% of maximum heart rate, and a 10-minute cool-down); (2) resistance training (40 moderate-intensity exercises four times a week: four sets of 10 resistance exercises repeated 10-12 times); (3) aerobic and resistance training combined; or (4) no training.

After just four weeks, flow-mediated dilation measurements showed better endothelial function among all the exercising participants, from about 4% before the given training program to approximately 10% (normal function). No significant improvement was seen among the non-exercisers, with flow-mediated dilation rising from 4.3% to 5.1%.

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However, one month after regular exercise was stopped, the improvements in endothelial function ceased, indicating the need for long-term adherence to such training programs.

In another exercise-related study, researchers found that men who don’t increase their level of physical activity until middle age can eventually experience the same reduction in mortality as men who had always engaged in a high level of activity. “This reduction is comparable with that associated with smoking cessation,” the authors observe (BMJ. 2009;338:b688).