There were a couple of heart attacks in this study, but these coronary heart disease patients endured hard exercise surprisingly well.
High-intensity exercise has both aerobic and cardio benefits. But, a new paper appearing in Circulation says, the idea that "vigorous exercise could acutely and transiently increase the risk of sudden cardiac death and myocardial infarction in susceptible persons" keeps doctors from recommending it for coronoary heart disease patients.
So these Norwegian researchers decided to test it out. They subjected over 4,800 cardiac patients to high- and moderate-intensity interval exercise training. 36% of the subjects got the high-intensity training -- that is, one-hour sessions of exercise at 85-95% of peak heart rate with rest periods.
40% of the participants had undergone angioplasty, and 35% coronary surgery; 7% had experienced heart failure, and 7% a myocardial infarction.
"The training modality typically consisted of treadmill exercise," say the authors, "but also aerobic group training, biking sessions, and outdoor walking and cross-country skiing was performed."
All participants were given stress tests for cardio fitness before inclusion -- interestingly, the researchers found exclusion on this basis was "very rare."
It wasn't a total success: There were a few heart attacks -- "one cardiac arrest with fatal outcome during moderate-intensity exercise, and two non-fatal cardiac arrests during high-intensity exercise," the authors report.
But given the sample size, that works out to one adverse event per 129,456 hours of moderate-intensity exercise -- and one per 23,182 hours of high-intensity exercise. Thus, they're both low-risk activities.
Now, don't send your heart patients running up hills yet -- "The safety aspect of such high intensity exercise training programs should however be evaluated before it is used in large, unselected groups of CHD patients," says the authors.
But patients who are game should be fast-tracked -- not only for the possible health benefits, but also to give them more evidence that they don't have to slow to a crawl just because they've had heart trouble.