Q. Many years ago, I practiced interval training. I pushed myself for three to four minutes up to five times during a workout. I want to start working out again, but wonder if this kind of training would be safe for me. I’m a lot older now and have some heart disease.
A. High-intensity interval training, or HIIT, is still a common approach for good reason: demanding a lot from your cardiovascular system for brief periods does more to enhance your fitness than chugging along at a slower rate for a longer time. Is it safe? There is probably a modest increase in risk while you are pushing yourself. Most cardiac rehabilitation programs do not use HIIT, but instead supervise individuals as they undertake a moderate continuous training program. The rate of major cardiac problems with this approach is very low. I personally think that mixing HIIT a couple times a week into a varied daily routine is a great way to stay in shape and avoid repetitive motion injuries. Since you have some heart disease, you should have a stress test before you start training again. I would urge you to start your HIIT routine under the supervision of a cardiac rehabilitation program. Anyone who cannot do high-intensity exercise should not take this to mean they might as well just sit back and watch life go by. Regardless of your age, the most important thing you can do is to get out of your chair and do some form of exercise. Simply walking briskly for 30 minutes a day can bring enormous heart benefits, as well as improving how you feel and your sense of well-being.
— Thomas Lee, M.D. and Richard Lee, M.D.
Co-Editors in Chief, Harvard Heart Letter