Is High-Intensity, Interval Exercise Safe for Heart Patients?

Medically reviewed in November 2019

For the last several decades, cardiologists and exercise physiologists have recommended regular aerobic exercise to improve cardiac function and lower disease risk factors for those with cardiovascular disease. In more recent years, this recommendation has also included high intensity interval exercise (HIIE), an approach that includes short periods of intense anaerobic exercise with less intense recovery periods. However, some healthcare providers question the safety and effectiveness of HIIE.

The jury is still out on the overall safety of HIIE training for heart patients

Traditional Cardiac Rehab Exercise
I’ve spent nearly twenty years working in cardiac rehabilitation, applying the more traditional principles of exercise for patients diagnosed with cardiovascular disease.

These traditional guidelines—which are recommended by organizations such as the American College of Sports Medicine (ACSM), the American Heart Association and The American College of Cardiology—recommend light-to-moderate intensity exercise that can be sustained for several minutes or up to an hour or greater.

The exercise component of the Ornish Reversal Program (Intensive Cardiac Rehabilitation) recommends a minimum of 30 minutes a day, or an hour every other day, for a total of 3-5 hours of aerobic exercise per week. This program does not include high intensity interval exercise.

More specifically, the ACSM recommends exercising at a range of 40 to 85 percent of a person’s maximum aerobic capacity. Aerobic capacity can be measured with a treadmill stress test, and using this data a healthcare professional can very accurately calculate a person’s target heart range to match the 40 to 85 percent guideline. The healthcare professional—in many cases a nurse or exercise physiologist working with your physician—would create an exercise prescription designed specifically for you based on your current fitness level and medical history.

I’ve personally found these guidelines to be both beneficial and very safe for the majority of patients participating in supervised cardiac rehabilitation. These guidelines also allow the healthcare professional to adequately challenge every type of patient, from those who have never trained to seasoned athletes.

Does High Intensity Interval Exercise Help Heart Patients?
Some cardiac rehabilitation programs are now utilizing HIIE training for many of their patients. HIIE training involves short bursts of high intensity exercise, often greater than 90 percent of a person’s maximum aerobic capacity, broken up by periods of rest or low intensity exercise.

Some research has shown that HIIE has superior benefits over the more traditional, moderate-intensity continuous exercise. For example, a study by Wisloff et al published in the journal Circulation showed exercise intensity was an important factor for reversing left ventricular remodeling and improving aerobic capacity, endothelial function and quality of life in patients with post-infarction heart failure.

However, the jury is still out on the overall safety of HIIE training. A 2012 study in the journal Circulation by Rognmo, Moholdt, Bakken, et al found that the rate of cardiovascular events in both groups evaluated was one fatal cardiac arrest during moderate-intensity exercise (129 to 456 exercise hours) and two nonfatal cardiac arrests during high-intensity interval exercise (46 to 364 exercise hours).

Research continues in this area, but most healthcare providers have yet to fully support HIIE for people with cardiovascular disease. In my opinion, most recent cardiac patients are not conditioned enough or simply not psychologically ready to participate in HIIE training, even in a supervised setting.

Should I Try High Intensity Interval Training?
There are significant benefits that can be achieved by both moderate-intensity aerobic training and HIIE. But if you’re going to try HIIE, it’s vitally important to get the approval of an experienced healthcare professional. They will take into account your abilities, health history and goals to create an exercise prescription that is safe, effective and sustainable.

If you and your healthcare provider opt for a HIIE program, make sure you are not sacrificing form and safety for intensity and volume. Read the Ornish Living article, Understand Your Workout Goals and Limits.

This content was originally published on Ornish Living.

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