Blood Flow Restriction Resistance Training Intervention on Vascular Function

Study Overview
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Brief Summary
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The purpose of this study is to investigate the effect of blood flow restriction (BFR) resistance training on vascular function. The investigators aim to compare the effects of different BFR devices (wide-rigid cuffs and narrow elastic bands) on vascular function. The investigators hypothesize that BFR resistance training with wide-rigid cuffs might have a minor negative effect (short-term and reversible) on vascular function, while BFR resistance training with narrow-elastic bands may improve vascular function. Both training methods are equally effective in increasing muscle strength.

Detailed Description
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Blood flow restriction (BFR) resistance training has been proven to be effective in increasing muscle mass and strength. During BFR training, cuffs (similar to blood pressure cuffs) are placed on the proximal ends of the extremities to partially occlude arterial blood flow to the working muscles and fully restrict venous outflow from the working muscle. The metabolites produced by the working muscle during exercise are trapped in the working muscle, which causes metabolic stress to augment muscle adaptation. Typically, two types of cuffs are used in the BFR training: the narrow-elastic bands and wide-rigid nylon cuffs adapted from surgical tourniquets and blood pressure cuffs. Currently, the effect of BFR training on vascular function remains unclear. When the cuffs are removed after BFR training, there will be a reactive hyperemic blood flow to wash out all the metabolites produced during exercise. This reactive hyperemic blood flow also will impose shear stress on the arterial vessel wall. The shear stress will lead to an increase in vasodilator factors, which lead to an improvement in vascular function. However, other studies have pointed out that BFR training might cause a negative effect on vascular function when the occlusion pressure was too high. The possible mechanisms of the negative effect might be ischemia-reperfusion injury and retrograde shear stress in the artery. The wide-rigid cuffs are easily available but have the potential to inhibit the expansion of muscle upon increased blood flow accompanying exercise and muscle contraction while the narrow-elastic bands do not prevent the expansion. To the investigators' best knowledge, there is no study directly comparing different BFR cuffs on vascular function. Thus, the aim of the present study is to compare the effects of different BFR cuffs on vascular function (evaluated by flow-mediated dilation, a non-invasive measure of endothelial-derived vasodilation).

Official Title
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The Effect of Blood Flow Restriction Resistance Training on Vascular Function: Wide-Rigid Cuffs vs. Narrow-Elastic Bands

Conditions
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Endothelial Function

Intervention / Treatment
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* Behavioral: Blood flow restriction resistance training


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Apparently healthy, sedentary or recreationally active young adults aged between 18 - 40 years old and signed the informed consent. Exclusion Criteria: A current COVID-19 diagnosis morbid obesity hypertension smoking overt cardiovascular disease using any medication that might affect the cardiovascular system current participation in resistance training.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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All

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: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Wide-rigid cuff<br>The wide-rigid cuff will be randomly assigned to one of the subject's arms. | Behavioral: Blood flow restriction resistance training<br>* The participants will receive a 2-week exercise training program (3 times per week). Each training session will consist of 3 resistance training exercises with two blood flow restriction devices (wide-rigid cuff and narrow-elastic band). For both arms, the participants will perform the same exercise with different BFR devices.<br>|
| Experimental: Narrow-elastic band<br>The narrow-elastic band will be randomly assigned to another arm of the subject. | Behavioral: Blood flow restriction resistance training<br>* The participants will receive a 2-week exercise training program (3 times per week). Each training session will consist of 3 resistance training exercises with two blood flow restriction devices (wide-rigid cuff and narrow-elastic band). For both arms, the participants will perform the same exercise with different BFR devices.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from baseline vascular function at 2 weeks | Flow-mediated dilation evaluated by an ultrasound machine | Baseline measurement and measurement at 2 weeks | 
| Change from baseline muscle strength at 2 weeks | Measured by a cable machine in the gym | Baseline measurement and measurement at 2 weeks | 
| Change from baseline grip strength at 2 weeks | Measured by a hand dynamometer | Baseline measurement and measurement at 2 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from baseline body fat percentage at 2 weeks | Measured by a bioelectrical impedance analysis machine | Baseline measurement and measurement at 2 weeks | 
| Change from baseline fat mass at 2 weeks | Measured by a bioelectrical impedance analysis machine | Baseline measurement and measurement at 2 weeks | 
| Change from baseline lean body mass at 2 weeks | Measured by a bioelectrical impedance analysis machine | Baseline measurement and measurement at 2 weeks | 
| Blood flow responses to different types of cuff | Measured by an ultrasound machine | Baseline measurement | 
| Blood flow responses to different types of cuff | Measured by an ultrasound machine | At 2 weeks | 
| Change from baseline arterial stiffness at 2 weeks | Evaluated by the Omron VP-1000plus device (Non-invasive measurement) | Baseline measurement and measurement at 2 weeks | 
| Change from baseline blood lactate concentration | Measured by a lactometer | At 10 minutes before the training sessions (baseline measurement) and at 10 minutes after the training sessions | 
| Changes from baseline heart rate at the end of each exercise during all the training sessions | Measured by a heart rate monitor | At 10 minutes before the training sessions (baseline measurement), at 10 minutes, 20 minutes, and 30 minutes during the training sessions | 
| Change from baseline blood pressure at the end of each exercise during all the training sessions | Measured by an Omron digital blood pressure monitor | At 10 minutes before the training sessions (baseline measurement), at 10 minutes, 20 minutes, and 30 minutes during the training sessions | 
| Change of the perceived exertion | Borg rating of perceived exertion scale | At 10 minutes, 20 minutes, and 30 minutes during the training sessions |