Prescriptions for Cardiac Disease
Exercise Protocols that Achieve Triple the Results with the Same or Smaller Time Investment
Consistent with the Exercise Is Medicine initiative, multiple guidelines recommend prescriptions for exercise training in the treatment of cardiac diseases.1-3 They specifically refer to exercise protocols sometimes categorized as moderate-intensity continuous training (MCT) - for instance: jogging on a treadmill for a set amount of time.
While MCT has proven effective, there is emerging interest in alternative exercise protocols that, in some instances, have achieved dramatically greater improvement with the same or a lesser time investment. Shigenori Ito, MD, PhD, conducted a systematic review of these protocols as used in the treatment of cardiac disease. His results were published recently in the World Journal of Cardiology. 4 These alternative exercise training protocols fall into the category of high-intensity interval training (HIIT). As opposed to the continuous, moderate exertion of MCT, HIIT involves short periods of high-intensity exertion separated by periods of lower intensity exercise/active rest.
A number of randomized, controlled trials (RCTs) have found HIIT superior to MCT across a range of measures: skeletal muscles,5-8 respiration,8-9 cardiac function,6,8,10,11 exercise capacity,11 and more. Among such measures, peak oxygen consumption (V02peak) stands out as an important indicator of aerobic capacity and cardiac health. It is a strong predictor of future health, all-cause mortality, cardiovascular risks, and cardiovascular disease development.12-15 As such, exercise training can be prescribed for primary or secondary prevention of cardiac disorders.
In the current study, Dr. Ito reviewed RCTs comparing V02peak improvement from HIIT versus MCT among patients with cardiac diseases. Across 20 RCTs, patient groups included coronary artery disease, post coronary artery bypass graft, metabolic syndrome, post myocardial infarction, post percutaneous coronary intervention, congestive heart failure, and diastolic dysfunction.
The trials also used various HIIT protocols with different intervals, number of sessions, and levels of exertion. Timeframes ranged from 4 to 12 weeks. MCT achieved improvement in most of the studies, but HIIT achieved improvement in all of the studies. Additionally, HIIT scored greater improvement than MCT, by 25% or more, in 80% of the studies. In a third of the studies, HIIT achieved V02peak improvement that was more than double the improvement caused by MCT.
In a fifth of the studies, HIIT accomplished V02peak improvement that was more than triple that of MCT. In cardiac rehabilitation, there is some evidence to suggest that patient adherence may be higher with HIIT compared to MCT.4,17 This may stem from a combination of the motivation stemming from greater results, plans that are less monotonous, and the level of one-to-one clinician involvement during the first weeks of implementation.
Additionally, using a narrow definition of HIIT, HIIT is generally considered safe and appropriate for the elderly, the sedentary, and some patients with cardiac disease, as long as plans are initiated with professional supervision. In one study involving three cardiac rehabilitation centres, 129,456 hours of MCT had one associated fatal cardiac arrest, while 46,364 hours of HIIT had two non-fatal cardiac arrests.17
When you have patients who need to mitigate cardiovascular risk factors or who have cardiac disease but want to safely improve fitness in the most efficient way, please consider a referral to exercise physiology at Advanced Physiotherapy. Different training protocols offer different levels of efficacy and safety. An exercise physiologist can work with your patient to determine the best training protocol for your medical goals, patient safety, and patient motivation.
1. Garber CE, Blissmer B, Deschenes MR, Franklin BA, Lamonte MJ, Lee IM, Nieman DC, Swain DP. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: guidance for prescribing exercise. (2011): 1334-1359.
2. Piepoli MF, Corrà U, Adamopoulos S, Benzer W, Bjarnason-Wehrens B, Cupples M, Dendale P, Doherty P, Gaita D, Höfer S, McGee H. Secondary prevention in the clinical management of patients with cardiovascular diseases. Core components, standards and outcome measures for referral and delivery: a policy statement from the cardiac rehabilitation section of the European Association for Cardiovascular Prevention & Rehabilitation. Endorsed by the Committee for Practice Guidelines of the European Society of Cardiology. European Journal of Preventive Cardiology. 2014 Jun 1;21(6):664-81.
3. JCS Joint Working Group. Guidelines for Rehabilitation in Patients With Cardiovascular Disease (JCS 2012)–Digest Version–. Circulation Journal. 2014:CJ-66.
4. Ito S. High-intensity interval training for health benefits and care of cardiac diseases-the key to an efficient exercise protocol. World Journal of Cardiology. 2019 Jul 26;11(7):171.
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6. Hollekim-Strand SM, Bjørgaas MR, Albrektsen G, Tjønna AE, Wisløff U, Ingul CB. High-intensity interval exercise effectively improves cardiac function in patients with type 2 diabetes mellitus and diastolic dysfunction: a randomized controlled trial. Journal of the American College of Cardiology. 2014 Oct 21;64(16):1758-60.
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9. Rocco EA, Prado DM, Silva AG, Lazzari J, Bortz PC, Rocco DF, Rosa CG, Furlan V. Effect of continuous and interval exercise training on the PETCO2 response during a graded exercise test in patients with coronary artery disease. Clinics. 2012;67:623-8.
10. Angadi SS, Mookadam F, Lee CD, Tucker WJ, Haykowsky MJ, Gaesser GA. High-intensity interval training vs. moderate-intensity continuous exercise training in heart failure with preserved ejection fraction: a pilot study. Journal of Applied Physiology. 2015 Sep 15;119(6):753-8.
11. Freyssin C, Verkindt C, Prieur F, Benaich P, Maunier S, Blanc P. Cardiac rehabilitation in chronic heart failure: effect of an 8-week, high-intensity interval training versus continuous training. Archives of Physical Medicine and Rehabilitation. 2012 Aug 1;93(8):1359-64.
12. Blair SN, Kohl HW, Barlow CE, Paffenbarger RS, Gibbons LW, Macera CA. Changes in physical fitness and allcause mortality: a prospective study of healthy and unhealthy men. JAMA. 1995 Apr 12;273(14):1093-8.
13. Lee DC, Sui X, Ortega FB, Kim YS, Church TS, Winett RA, Ekelund U, Katzmarzyk PT, Blair SN. Comparisons of leisure-time physical activity and cardiorespiratory fitness as predictors of all-cause mortality in men and women. British Journal of Sports Medicine. 2011 May 1;45(6):504-10.
14. Myers J, Prakash M, Froelicher V, Do D, Partington S, Atwood JE. Exercise capacity and mortality among men referred for exercise testing. New England Journal of Medicine. 2002 Mar 14;346(11):793-801.
15. DeFina LF, Haskell WL, Willis BL, Barlow CE, Finley CE, Levine BD, Cooper KH. Physical activity versus cardiorespiratory fitness: two (partly) distinct components of cardiovascular health?. Progress in Cardiovascular Diseases. 2015 Jan 1;57(4):324-9.
16. Myers J, McAuley P, Lavie CJ, Despres JP, Arena R, Kokkinos P. Physical activity and cardiorespiratory fitness as major markers of cardiovascular risk: their independent and interwoven importance to health status. Progress in Cardiovascular Diseases. 2015 Jan 1;57(4):306-14.
17. Aamot IL, Karlsen T, Dalen H, Støylen A. Long‐term exercise adherence after high‐intensity interval training in cardiac rehabilitation: a randomized study. Physiotherapy Research International. 2016 Mar;21(1):54-64.