Written by Joyce Smith, BS. Study found both high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) to be effective for cardiac rehabilitation training, but recommend HIIT only as an adjunct therapy to MICT.
Exercise, the cornerstone of cardiac rehabilitation, plays an important role in the reduction of cardiovascular disease and all-cause mortality 1. An early 2002 study of 12,169 males with CHD and participating in a cardiac rehabilitation regimen concluded that exercise capacity as determined by direct measure of peak VO2 (the volume of oxygen consumption) has a long- term influence on prognosis in men after myocardial infarct (MI) 2, while a 2008 study of 2,812 patients with CHD further validated an inverse association between peak VO2 and risk of death 3. According to results of two recent studies, HIIT offered greater improvements in aerobic capacity (VO2) than MICT in patients with CAD 4,5; however, further research investigating the feasibility, safety and long-term adherence to HIIT is required.
The purpose of this current study 6 was to determine whether HIIT is superior to MICT for improving cardiorespiratory fitness and secondly, to evaluate the safety and practicality of an HIIT program in terms of greater exercise adherence, reduced cardiovascular risk factors, and improved quality of life of the participants. In a 12-month randomized clinical trial, 93 participants with angiographically proven coronary artery disease (CAD) underwent four weeks of supervised HIIT or MICT training in a private hospital cardiac rehabilitation program (three sessions per week; two supervised and one at home), followed by a long-term home-based training of three sessions per week for over 11 months. Mean age of participants was 65 years, and 84% were men. Baseline VO2 peak was approximately 27.5 mL/kg/min.
Cardiopulmonary exercise test (CPET) results showed that individuals randomized to HIIT had a 10% boost in VO2 peak from baseline to 4 weeks, compared with 4% improvement among participants receiving MICT during this time (P=0.02); however, at 12 months, improvement was similar between the two study arms (10% vs 7%, P=0.30). HIIT participants who followed the program more rigorously derived a longer lasting benefit. While participants in the four- week, hospital- based cardiac rehabilitation program had high feasibility scores and low withdrawal rates (91% for both HIIT and MICT groups), the following 12- month home training had high dropout rates for both HIIT and MICT participants (53% and 43% respectively).
HIIT and MICT were both practical and easy to implement, and there were no deaths or cardiovascular events as a result of either type of exercise training. The only adverse event was an episode of post-exercise hypotension in a member of the HIIT group that was due to diuretic-induced dehydration. Overall, supervised MICT was associated with a greater decrease in systolic and diastolic blood pressure compared to HIIT (BP; -3/2 mmHg vs +2/+1 mmHg, P<0.05). However, people with hypertension at baseline experienced similar reductions in BP after exercise. Study findings revealed much better results in the shorter 4-week cardio rehabilitation than longer term at home therapy and support the use of HIIT in cardiac rehabilitation programs, but only as an adjunct or alternative modality to moderate-intensity exercise. Study limitations include the questionable generalizability to other centers and the inclusion of only a few women (16%) as well as people with left ventricular dysfunction, type 2 diabetes, and a history of tobacco smoking.
Source: Taylor, Jenna L., David J. Holland, Shelley E. Keating, Michael D. Leveritt, Sjaan R. Gomersall, Alex V. Rowlands, Tom G. Bailey, and Jeff S. Coombes. “Short-term and Long-term Feasibility, Safety, and Efficacy of High-Intensity Interval Training in Cardiac Rehabilitation: The FITR Heart Study Randomized Clinical Trial.” JAMA cardiology.
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Posted September 29. 2020.
Joyce Smith, BS, is a degreed laboratory technologist. She received her bachelor of arts with a major in Chemistry and a minor in Biology from the University of Saskatchewan and her internship through the University of Saskatchewan College of Medicine and the Royal University Hospital in Saskatoon, Saskatchewan. She currently resides in Bloomingdale, IL.
References:
- Martin BJ, Hauer T, Arena R, et al. Cardiac rehabilitation attendance and outcomes in coronary artery disease patients. Circulation. 2012;126(6):677-687.
- Kavanagh T, Mertens DJ, Hamm LF, et al. Prediction of long-term prognosis in 12 169 men referred for cardiac rehabilitation. Circulation. 2002;106(6):666-671.
- Keteyian SJ, Brawner CA, Savage PD, et al. Peak aerobic capacity predicts prognosis in patients with coronary heart disease. Am Heart J. 2008;156(2):292-300.
- Elliott AD, Rajopadhyaya K, Bentley DJ, Beltrame JF, Aromataris EC. Interval training versus continuous exercise in patients with coronary artery disease: a meta-analysis. Heart, lung & circulation. 2015;24(2):149-157.
- Pattyn N, Coeckelberghs E, Buys R, Cornelissen VA, Vanhees L. Aerobic interval training vs. moderate continuous training in coronary artery disease patients: a systematic review and meta-analysis. Sports medicine (Auckland, NZ). 2014;44(5):687-700.
- Taylor JL, Holland DJ, Keating SE, et al. Short-term and Long-term Feasibility, Safety, and Efficacy of High-Intensity Interval Training in Cardiac Rehabilitation: The FITR Heart Study Randomized Clinical Trial. JAMA cardiology. 2020.
