Cardiovascular Effects of High-Intensity Interval Training (HIIT)

Study Overview
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Brief Summary
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The purpose of this study is to determine the effect of high-intensity interval training (HIIT) in comparison to moderate-intensity continuous training (MCT) on blood pressure, blood vessel function, and blood pressure reactivity.

Detailed Description
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It is estimated that one-third of the adult population in the United States has blood pressure values that are classified as prehypertension. This slight elevation in blood pressure has been shown to result in an increased risk for developing hypertension and cardiovascular disease. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC7) recommends lifestyle modifications for individuals classified as prehypertensive. One lifestyle modification suggested by JNC7 is regular physical activity. Aerobic exercise, like moderate-intensity continuous training (MCT), has been shown to improve blood pressure, blood vessel function, and arterial stiffness in those with prehypertension. However, a major barrier to exercise adherence is the time commitment required. High-Intensity Interval Training (HIIT), which requires individuals to work at higher intensities for shorter durations, may offer an alternative training design that would reduce the time commitment. Previous studies have shown HIIT to be equal to or better at improving cardiorespiratory fitness and blood vessel function in multiple populations. Limited information is present on HIIT training in those with prehypertension. In this study, participants will be randomized into one of the two training program designs mentioned above (MCT or HIIT). Both programs will be completed over an 8-week period (3 sessions per week) and each training session will be supervised. Participants will complete testing visits before and after the training program to collect measures of cardiovascular health (exercise capacity, blood pressure, blood vessel function, and blood pressure reactivity). The goal is to compare the effects of the training programs on these measures of cardiovascular health.

Official Title
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Cardiovascular Effects of High-Intensity Interval Training (HIIT) and Moderate-Intensity Continuous Training (MCT)

Conditions
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Healthy Sedentary Adults With BP <140/90

Intervention / Treatment
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* Behavioral: High-Intensity Interval Training
* Behavioral: Moderate-Intensity Continuous Training


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Blood Pressure less than 140/90 mmHg Sedentary Exclusion Criteria: Known or major signs/symptoms of cardiovascular, pulmonary, renal, or metabolic disease Cancer Use of antihypertensive medication Current tobacco use BMI (body mass index) less than 30 kg/m2 Postmenopausal Current pregnancy Current hormone replacement therapy Participating in regular aerobic exercise at least three times a week for 30 minutes at a moderate intensity for the past 3 months or more Not able to regularly exercise for any reason

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 44 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: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: High-Intensity Interval Training<br>8 weeks of high-intensity interval training. Three sessions per week will be performed (24 total sessions). | Behavioral: High-Intensity Interval Training<br>* Supervised exercise sessions will be performed on a upright cycle ergometer. Training sessions involve 20 minutes of exercise by completing 10 repetitions of 60 seconds of exercise at 90-95% maximal heart rate with 60 seconds of active rest between each repetition at 50-60% maximal heart rate.<br>|
| Active Comparator: Moderate-Intensity Continuous Training<br>8 weeks of moderate-intensity continuous training. Three sessions per week will be performed (24 total sessions). | Behavioral: Moderate-Intensity Continuous Training<br>* Supervised exercise sessions will be performed on a upright cycle ergometer. Training sessions involve 30 minutes of continuous exercise at 65-70% maximal heart rate.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Blood Pressure | Resting blood pressures measuring by automated oscillometric device | Change from baseline resting blood pressure at 8 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Peak Aerobic Capacity | Peak oxygen uptake (VO2peak/max) during incremental cycling exercise until exhaustion | Change from baseline VO2peak at 8 weeks | 
| 24-Hour Ambulatory Blood Pressure | 24 hours of continuous ambulatory blood pressure monitoring by oscillometric device | Change from baseline 24-hour ambulatory blood pressure at 8 weeks | 
| Pulse Wave Analysis | Central blood pressure measures assessed by radial tonometry | Change from baseline central blood pressure measures at 8 weeks | 
| Endothelial Function | Assessed by brachial artery flow mediated dilation and change in blood in femoral artery in response to passive limb movement | Change from baseline endothelial function at 8 weeks | 
| Arterial stiffness | Pulse wave velocity measures (carotid to femoral and femoral to distal) assessed by applanation tonometry | Change from baseline pulse wave velocity measures at 8 weeks | 
| Blood Pressure Reactivity | Blood pressure response to graded exercise test and handgrip exercise | Change from baseline blood pressure reactivity at 8 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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High-Intensity Interval Training, Exercise, Cardiovascular Health, Blood Pressure