A Study to Compare the Effectiveness of Different High-intensity Interval Training Programs in Cardiac Rehabilitation

Study Overview
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Brief Summary
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The purpose of the study is to examine the effect of two different high intensity interval training (HIIT) prescription approaches on improving fitness, heart function, and the ability of the body's muscles to receive oxygen.

Official Title
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Efficacy of Prescription Methods for High-intensity Interval Training in Patients Enrolled in Outpatient Cardiac Rehabilitation

Conditions
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Cardiac Rehabilitation

Intervention / Treatment
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* Other: Progressive High Intensity Interval Training (PRO-HIIT)
* Other: Constant High Intensity Interval Training (CON-HIIT)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult 18 years and older. English speaking. Able to provide consent. Has a qualifying indication for center-based cardiac rehabilitation that is non-surgical (i.e., Acute coronary syndrome, myocardial infarction, percutaneous coronary intervention, and stable angina). Exclusion Criteria: Participants referred to cardiac rehabilitation following coronary artery bypass surgery, heart valve repair/replacement, heart transplant, or those with ventricular assist devices. Patients who are unable to engage in a regularly structured exercise training program as part of a clinically indicated center-based outpatient cardiac rehabilitation program are not eligible. Patients unable/unwilling to provide informed consent will not be enrolled. Patients identified as having a contraindication to high intensity exercise.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Standard-care interval-training group<br>Subjects will complete a standard interval-training program that remains constant for the entire 12 weeks of cardiac rehabilitation. | Other: Constant High Intensity Interval Training (CON-HIIT)<br>* Individual exercise training sessions, involving two weeks of moderate intensity continuous exercise and 10 weeks of interval exercise training. This protocol involves a constant protocol of training, including six high-intensity intervals (at an RPE of 15-18) of 1-min separated by five low-intensity intervals of 2-min.<br>|
| Experimental: Progressive interval-training group<br>Subjects will complete an interval-training program during which the number of intervals and the duration of each interval are changed across the 12-week cardiac rehabilitation program. | Other: Progressive High Intensity Interval Training (PRO-HIIT)<br>* Individual exercise training sessions, involving two weeks of moderate intensity continuous exercise and 10 weeks of interval exercise training. This protocol involves progression of training of 3 stages: 1) six high-intensity intervals (at an RPE of 15-18) of 1-min separated by five low-intensity intervals of 2-min; 2) three high-intensity intervals of 2-min separated by two low-intensity intervals of 4-min, and a further 2-min of low intensity following the last interval before cool-down; and 3) three high-intensity intervals of 3-min separated by two low-intensity intervals of 3-min, and a further 1-min of low intensity following last interval before cool-down.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in cardiorepiratory fitness | Measure as peak oxygen consumption (VO2 peak) | Pre and post study completion, approximately 12 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in oxygen uptake response time | Measured as exponential time-constant of pulmonary oxygen uptake at exercise onset | Weekly, over 12 weeks | 
| Change in locomotor muscle oxygenation | Measured as tissue oxygen saturation by near-infrared spectroscopy (NIRS) | Pre and post study completion, 12 weeks | 
| Change in metaboreflex stimulation | Measured as changes in blood pressure during recovery from exercise | Pre and post study completion, 12 weeks | 
| Changes in mechanoreflex stimulation and sensitization | Measured as changes in blood pressure during recovery from exercise | Pre and post study completion, 12 weeks | 
| Change in cardiac function | Measured as global longitudinal strain by echocardiography at rest and during sub-maximal exercise | Pre and post study completion, 12 weeks | 
| Change in body composition | Measured as fat mass by dual-energy x-ray absorptiometry | Pre and post study completion, 12 weeks | 
| Change in blood pressure | Measured as resting and mean 24-hr blood pressures by ambulatory blood pressure monitor | Pre and post study completion, 12 weeks | 
| Change in blood lipids | Measured as total-cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides | Pre and post study completion, 12 weeks | 
| Change in physical activity | Measured as minutes spent in moderate-vigorous physical activity, by accelerometer monitor | Pre and post study completion, 12 weeks |