High-Intensity Interval Training in Cardiac Rehabilitation: Impact on Fat Mass in Patients With Myocardial Infarction

Objective To examine the effect of high-intensity interval training (HIIT) on body fat mass and distribution in patients with myocardial infarction (MI) who underwent cardiac rehabilitation (CR). Patients and Methods We retrospectively screened 391 consecutive patients with MI enrolled in CR between September 1, 2015, and February 28, 2018. We included 120 patients who completed 36 CR sessions and underwent pretest-posttest dual-energy x-ray absorptiometry; 90 engaged in HIIT, and 30 engaged in moderate-intensity continuous training (MICT). High-intensity interval training included 4 to 8 alternating intervals of high- (30-60 seconds at a rating of perceived exertion [RPE] of 15-17 [Borg scale range, 6-20]) and low-intensity (1-5 minutes at RPE <14), and MICT performed for 20 to 45 minutes of exercise at an RPE of 12 to 14. Body weight, fat mass, and lean mass were measured via dual-energy x-ray absorptiometry with lipid profile measured via clinical procedures. Results The HIIT and MICT groups were similar in age (67 vs 67 years), sex (26.7% [24 of 90 patients in the HIIT group] vs 26.7% [8 of 30 in the MICT group), and body mass index (30.3 vs 29.5 kg/m2) at baseline. The HIIT group had greater reductions in body fat percentage (P<.001), fat mass (P<.001), abdominal fat percentage (P<.001), waist circumference (P=.01), total cholesterol (P=.002), low-density lipoprotein cholesterol (P<.001), and triglycerides (P=.006). Improvements in total body mass and body mass index were not different across groups. After matching exercise duration, exercise intensity, and energy expenditure, HIIT-induced improvements in total fat mass (P=.02), body fat percentage (P=.01), and abdominal fat percentage (P=.02) persisted. Conclusion Our data suggest that supervised HIIT results in significant reductions in total fat mass (P<.001) and abdominal fat percentage (P<.001) and improved lipid profile in patients with MI who undergo CR.