An increasing number of programs to strengthen the heart after a heart attack are offering high-intensity interval training (HIIT), a popular exercise routine that alternates intense bursts of activity with short recovery periods to rapidly enhance exercise performance, in their cardiac rehab programs. Recent research findings show significant benefits of using HIIT over a more moderate exercise program among patients in a cardiac rehabilitation program, says researchers at the American College of Cardiology’s 68th Annual Scientific Session.
The researchers say that patients who patients who practiced HIIT, over more moderate experience including brisk walking and cycling, lost more body fat, gained more lean muscle mass and even trimmed more inches off their waists—all of which play a role in heart health. It is the first study to examine the effect of HIIT on body composition and fat distribution in patients with cardiovascular disease.
HIIT May Improve Your Cardiac Health
“A considerable amount of research on HIIT has been done in athletes to demonstrate its ability to improve total exercise capacity and sports performance,” said Yaoshan Dun, MD, PhD, a cardiac rehabilitation specialist at Mayo Clinic and Xiangya Hospital of Central South University in Changsha, China, and the study’s lead author, at the March 16 ACC session. “Scientists and clinicians are just beginning to recognize the power that HIIT may have in clinical populations to prevent a second heart attack in patients who’ve already had one,” says Dun.
Patients are advised to participate in cardiac rehabilitation to help recover their health and prevent future heart problems after suffering a heart attack. These programs typically include supervised exercise, help with managing medications, and counseling to help patients quit smoking, eat well and reduce stress.
Dun’s study examined outcomes from 120 cardiac rehabilitation patients treated at Mayo Clinic. In the first week of the study, all patients performed moderate-intensity continuous training. After that, patients who were physically capable of exercising at a high intensity for 20 minutes were offering an opportunity to try HIIT. Ninety patients switched to HIIT, the more intense exercise regimen, while 30 continued with the moderate exercise regimen. The participants in both groups were 67 years old, on average, and the two groups were also similar in terms of sex, body mass index (BMI), medications and other illnesses.
According to Dun, the exercise program included three sessions per week for 12 weeks. Patients performing HIIT alternated between one-minute periods of high-intensity exercise (for example, running at a pace that makes it very difficult to talk) and three to five-minute periods of low-intensity exercise, including walking at a casual pace, completing four to eight of these alternating intervals in a session. Patients who chose moderate-intensity training performed 30 continuous minutes of moderate exercise, such as walking or cycling at a pace that is challenging but sustainable.
Study Says HIIT Program Essential Cardiac Treatment
The study’s findings found that after 12 weeks, those patients performing HIIT had lost about 4 more pounds of body fat, while gaining about a pound and a half leaner muscle mass, and trimmed about an inch more off their waists, on average, than patients who did the moderate-intensity regimen. However, there was no significant difference between the two groups in terms of total body weight or BMI.
Health care providers know that both the amount and distribution of fat in a person’s body affects their risk for heart problems. Carrying more fat around the abdomen is associated with the greatest risk, they say. The lack of a significant difference between the two groups in terms of total body weight or BMI is likely related to the fact that participants performing HIIT gained muscle while losing fat, notes, saying that since HIIT-performing patients showed evidence of trimming more belly fat, those patients will likely experience greater benefits in terms of heart health.
“These findings support the use of HIIT as an essential treatment tool to improve body composition in heart attack patients enrolled in early outpatient cardiac rehabilitation,” adds Dun. “Our data suggest that, compared to moderate-intensity continuous training, supervised HIIT results in greater improvement in these patients. HIIT may contribute to better outcomes for patients with abdominal obesity who have cardiovascular risk factors or established heart disease,” he says.
Dun’s study was supported by the National Institutes of Health and Hunan Development and Reform Commission Foundation of China.