"Walk Often and Walk Far" – A New Approach to Cardiac Rehabilitation

In the 1970s, a typical cardiac rehabilitation (rehab) patient would undergo a lengthy hospitalization and was extremely deconditioned. Cardiac rehab protocols were developed with low calorie expenditures that reduced cardiac and total mortality in patients. Today, more than 80% of cardiac rehab patients are overweight, with over 40% classified as obese. More than 50% have insulin resistance. The focus of cardiac rehab has shifted to secondary prevention and risk factor reduction, yet programs still rely on protocols developed in the 1970's. Can a new rehab protocol that focuses on greater energy expenditure lead to greater weight loss and risk factor changes than the standard rehab program?

What was the study?

The study evaluated the effects of high-calorie expenditure exercise as compared to standard cardiac rehab in a randomized controlled clinical trial. The study was funded by the National Heart, Lung, and Blood Institute (NHLBI) and published in the journal Circulation, May 26, 2009.

• Participants were 60 men and 14 women with coronary heart disease. Their average age was 64 years and the average body mass index was 32 kg/m². The individuals were randomized to a standard cardiac rehab program or a high-calorie expenditure exercise program.
• The standard cardiac rehab exercise program consisted of 25-40 minutes of exercise three times per week at approximately 65-75% peak aerobic capacity. This included 25 minutes of treadmill walking and 8 minutes on 2 to 3 ergometers: cycle, rowing, or arm.
• The high-calorie expenditure exercise program emphasized longer duration, lower intensity, and more frequent exercise (45-60 minutes a session, 50-60% peak aerobic capacity, 5 to 7 times per week). Walking, rather than weight-supported exercises (such as cycling and rowing), was preferred to maximize calorie expenditure, which was targeted at 3,000-3,500 kcal/week. The protocol was essentially to "walk often and walk far."
• All patients received 16 hours of group dietary counseling and were given a target goal of consuming 500 kcal/day less than their predicted maintenance calories.

What did the study find?

• The high-calorie expenditure exercise program participants had double the weight loss compared to individuals in the standard program (8.2 kg vs. 3.7 kg). They also had a greater reduction in waist circumference and in fat mass as measured by dual energy x-ray absorptiometry.
• The high-calorie expenditure program participants had a greater improvement in their overall cardiometabolic risk profile, including a greater decrease in insulin resistance and a greater reduction in the total-to-HDL cholesterol ratio (13% vs. 3%).
• The high-calorie expenditure exercise participants' burned 615 kcal/day from exercise as compared to 169 kcal/day for the standard program.
• There was a similar reduction in dietary calorie intake between the groups (~300 kcal/day).
• The two groups had similar levels of exercise attendance (~85%), weight loss session attendance (~75%), and ratings of physical activity satisfaction.
• After 1 year, both groups had a weight regain of about 1 kg but maintained significantly lower body weight and body fat than at study entry.

What are the take-home messages?

• The high-calorie expenditure exercise program was better than the standard cardiac rehab program in promoting weight loss and improving cardiometabolic risk factors, including improving insulin resistance and cholesterol profile.
• The program was well-tolerated and was not associated with an increased rate of exercise-related overuse injuries or cardiac events. The effect of the program on long-term clinical outcomes is not yet known at this time.
• Exercise programs for risk reduction in overweight patients with heart disease should focus on increasing caloric expenditure. A low-exercise-intensity, high-calorie expenditure program may be well suited for community-based programs and can be utilized along with traditional components of cardiac rehab, such as counseling, to optimize risk factor benefits.
• The high-calorie expenditure exercise program should be considered the preferred exercise protocol for almost 80% of patients in the United States who are referred for cardiac rehab, according to the study authors. In an accompanying editorial, Dr. Thomas Allison of the Mayo Clinic states, "Although this is a small study in terms of patient numbers, the results are sufficiently worthwhile that serious consideration should be given to incorporating this research into standard clinical practice in cardiac rehabilitation."

Where can I learn more about the study?

• High-calorie-expenditure exercise: A new approach to cardiac rehabilitation for overweight coronary patients. Ades, P.A., et al., Circulation, 119:2671-2678, 2009, DOI: 10.1161/CIRCULATIONAHA.108.834184
• Improving weight loss in cardiac rehabilitation. Allison, T.A. Circulation, 119: 2650-2652, 2009, DOI: 10.1161/CIRCULATIONAHA.109.860569

Where can I get more information about cardiac rehab and weight control?

• NHLBI Diseases and Conditions Index (DCI): Cardiac Rehabilitation
• Your Guide to Living Well with Heart Disease (PDF)
• Aim for a Healthy Weight:
• Provider kit
• Patient booklet

Additional information on the study:

• Patient cardiac diagnoses included past myocardial infarction, coronary bypass surgery, percutaneous coronary intervention, or chronic stable angina.
• All participants were taking preventive cardiovascular medications, which included aspirin, statins, ß-blockers, angiotensin-converting enzyme inhibitors/blockers, and clopidogrel.
• The cardiometabolic risk profile included measures of insulin sensitivity, waist circumference, systolic and diastolic blood pressure, plasma glucose, triglycerides, HDL cholesterol, low-density lipoprotein cholesterol, cardiorespiratory fitness, PAI-1, and high-sensitivity C-reactive protein.