High-intensity Interval Training on Cardiorespiratory Fitness in Overweight Women

Study Overview
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Brief Summary
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High-intensity interval training (HIIT) is currently considered one of the most effective strategies to improved cardiorespiratory fitness, which is recognized as a protective factor for cardiovascular diseases and metabolic diseases such as overweight and obesity. However, current evidence is still limited and requires clarity (frequency, time per session and intensity) regarding to greater increases attributed to HIIT. The aim of this study is to compare the effect of a low-volume high-intensity interval training versus a moderate-intensity continuous exercise on maximal oxygen consumption in overweight women 18 to 44 years old.

Detailed Description
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Thirty-six women will be randomly assigned to one of two aerobic exercise on a real-life setting supervised for a physical activity instructor. The interventions will performed three times a week for ten-weeks (on alternate days). The first two weeks will correspond to the conditioning period (30 minutes between 55-65% of maximum heart rate (HRmax). From week three, 18 participants will perform 30 minutes of continuous exercise at an intensity between 65-75 % of HRmax, and the remaining 18 will complete 21.5 minutes of interval exercise at an intensity between 90-95% of HRmax, with recoveries between 50-55% of HRmax. All Participants will be evaluated to measure their maximal oxygen consumption, total body fat, waist circumference, body mass index, systolic blood pressure, diastolic blood pressure, prior to start the interventions and at the end of the program (week 11).

Official Title
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Effect of Low-volume High-intensity Interval Training on Cardiorespiratory Fitness and Total Body Fat in Overweight Women

Conditions
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Healthy Volunteers

Intervention / Treatment
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* Other: High-intensity interval training
* Other: Comparator: Moderate-intensity continuous exercise


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Overweight (≥ 25 kg/m-2) women 18 to 44 years. Healthy volunteers. Perform ≤ 600 Met/min/week. Exclusion Criteria: Perform high-intensity interval exercise in the last six month. Smoker. History of asthma. History of diabetes. History of hypertension. History of cardiovascular disease. History of coronary heart disease. Arrhythmias. Personal history of surgical procedures in the last three months Uncontrolled non-communicable diseases Under medical treatment with anticoagulants, beta-blockers, calcium antagonists, bronchodilators, and/or steroids. Psychological, neuromotor and/or osteo-muscular conditions that may affect participation in an exercise program. Psychoactive drug abuse.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 44 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

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> | Other: High-intensity interval training<br>* 21.5 minutes of high-intensity interval exercise at an intensity between 90-95 of HRmax (15x30 s), with recoveries at 50-60% of HRmax (14x60 s). 24 sessions, 3x weekly of walking and running outdoors on a sports field in a supervised manner.<br>|
| Active Comparator: Moderate-intensity continuous exercise<br> | Other: Comparator: Moderate-intensity continuous exercise<br>* 30 minutes of continuous exercise at an intensity between 65-75% of HRmax. 24 sessions, 3x weekly of walking and jogging outdoors on a sports field in a supervised manner<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in maximal oxygen consumption | Maximal oxygen consumption will be obtained using a graded exercise test on a treadmill (Trackmaster® model TMX 425C) using a portable K4b2 gas analyzer (Cosmed Inc., IL, USA) | Baseline and after 10 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in total body fat | Total body fat will be obtained using an Omron® HBF-510 (Omron Healthcare, Inc. Bannockburn, IL, USA) bioelectrical impedance machine. | Baseline and after 10 weeks |