Muscle Activation With Acute Bouts of Blood Flow Restricted Resistance Exercise

Study Overview
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Brief Summary
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Blood flow restricted (BFR) resistance exercise has been shown to improve skeletal muscle adaptations to low load resistance exercise. One of many adaptations with resistance training is neural adaptations that occur within the first few weeks of resistance training. It has been hypothesized that these neural adaptations are blunted when using blood flow restricted exercise. Therefore, the investigators propose to examine the muscle activation created by resistance exercise with different intensities with blood flow restriction and without blood flow restriction in sedentary compared to resistance-trained individuals. The investigators will recruit and completely study up to 30, previously untrained and resistance-trained, healthy, college-aged (18-40 years) males. Participants will come in the laboratory for 5 total visits. These visits will consist of a screening/familiarization visit, a strength testing visit, and 3 acute exercise visits. The acute exercise visits will consist of 2 blood flow restricted resistance sessions at different intensities and a traditional high load resistance exercise session. The 3 acute exercise visits will be randomized. The investigators will measure muscle mass (appendicular lean mass) using Dual Energy X-Ray Absorptiometry, muscle strength and endurance using isotonic and isokinetic testing, and muscle activation using surface electromyography. The investigators will also use near infrared spectroscopy (NIRS) to measure the muscle tissue (oxygen) saturation index (TSI) in the vastus lateralis during exercise. Finally, the investigators will also draw blood before and after each exercise session to measure hormones, metabolites, and markers of inflammation using commercially available assays (e.g., ELISAs).

Official Title
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Muscle Activation With Acute Bouts of Blood Flow Restricted Resistance Exercise Compared to High Load Resistance Exercise in Trained Versus Untrained Adults

Conditions
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Muscle, Acute Exercise

Intervention / Treatment
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* Behavioral: Traditional High Load Resistance Exercise (HLRE)
* Behavioral: Low Load Resistance Exercise with Blood Flow Restriction (LLBFR)
* Behavioral: Moderate Load Resistance Exercise with Blood Flow Restriction (MLBFR)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Capable and willing to give written informed consent Capable of understanding inclusion and exclusion criteria 18-40 years of age A waist circumference < 40 inches. No medical condition that would limit their participation in supervised exercise sessions based on the Physical Activity Readiness Questionnaire for Everyone (PARQ+) No current prescription medications Willing to allow researchers to use data and images (e.g., Dual Energy X-Ray Absorptiometry) for research purposes after study participation is completed Either untrained or resistance-trained by the following definitions: Untrained individuals are considered those that report less than two days per week of structured (> 30 minutes) moderate to vigorous-intensity aerobic exercise and less than two days per week of structured resistance training for the 3 months prior to study start. Resistance-trained individuals are considered those who report performing structured moderate to intense resistance exercise for at least three days per week for at least 2 years prior to study start. Exclusion Criteria: Self-report history of diabetes mellitus Self-report history of cardiovascular, peripheral vascular, cerebral vascular, pulmonary, or renal disease Self-report or evidence of uncontrolled hypertension > 150/85 (or measured) Self-report history of blood clotting disorders Self-report history of deep vein thrombosis or pulmonary embolism Self-report history of sickle cell trait Self-report history of varicose veins Self-report history of a myopathy leading to muscle loss, weakness, severe cramps or myalgia Self-report history of orthopedic limitations that would preclude them from participation in a dynamic exercise program Self-report history of musculoskeletal disorders (e.g., severe osteoarthritis, rheumatoid arthritis, avascular necrosis or osteonecrosis) Self-report history of neurological disorders (e.g., peripheral neuropathy, amyotrophic lateral sclerosis, multiple sclerosis, fibromyalgia, Parkinson's disease) Weight loss of > 10% in the last 3 months prior to screening Active tobacco use including smoking, vaping, or smokeless tobacco use Current consumption of > 14 alcoholic drinks per week based on self-report Any other condition that, in the judgement of the Principal Investigator and/or the Medical Director of this protocol, may interfere with study participation and adherence to the protocol

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

Sexes Eligible for Study
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Male

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 |
| --- | --- |
| Other: Resistance Trained<br>Resistance-trained individuals are considered those who report performing structured moderate to intense resistance exercise for at least three days per week for at least 2 years prior to study start. | Behavioral: Traditional High Load Resistance Exercise (HLRE)<br>* Participants will then perform 75% of tested 1RM for 3 sets of 12 repetitions at a pace of 1 repetition every 2 seconds on the dominant leg with one-minute rest between sets. After completing the HLRE protocol, participants will perform 2 post-exercise maximal voluntary contractions.<br>Behavioral: Low Load Resistance Exercise with Blood Flow Restriction (LLBFR)<br>* Participants will then perform 25% of tested 1RM for sets of 30, 15, 15, and 15 repetitions on the dominant leg at a pace of 1 repetition every 2 seconds with one-minute rest between sets. Participants will be fitted with an occlusion cuff on the proximal portion of the thigh. The limb occlusion pressure will be set at 60% blood flow occlusion and remain occluded throughout the exercise (Delfi Medical Innovations Personal Tourniquet System).<br>Behavioral: Moderate Load Resistance Exercise with Blood Flow Restriction (MLBFR)<br>* Participants will then perform 50% of tested 1RM for sets of 15, 8, 7, and 7 repetitions on the dominant leg at a pace of 1 repetition every 2 seconds with one-minute rest between sets. Participants will be fitted with an occlusion cuff on the proximal portion of the thigh. The limb occlusion pressure will be set at 60% blood flow occlusion and remain occluded throughout the exercise (Delfi Medical Innovations Personal Tourniquet System).<br>|
| Other: Untrained<br>Untrained individuals are considered those that report less than two days per week of structured (> 30 minutes) moderate to vigorous-intensity aerobic exercise and less than two days per week of structured resistance training for the 3 months prior to study start. | Behavioral: Traditional High Load Resistance Exercise (HLRE)<br>* Participants will then perform 75% of tested 1RM for 3 sets of 12 repetitions at a pace of 1 repetition every 2 seconds on the dominant leg with one-minute rest between sets. After completing the HLRE protocol, participants will perform 2 post-exercise maximal voluntary contractions.<br>Behavioral: Low Load Resistance Exercise with Blood Flow Restriction (LLBFR)<br>* Participants will then perform 25% of tested 1RM for sets of 30, 15, 15, and 15 repetitions on the dominant leg at a pace of 1 repetition every 2 seconds with one-minute rest between sets. Participants will be fitted with an occlusion cuff on the proximal portion of the thigh. The limb occlusion pressure will be set at 60% blood flow occlusion and remain occluded throughout the exercise (Delfi Medical Innovations Personal Tourniquet System).<br>Behavioral: Moderate Load Resistance Exercise with Blood Flow Restriction (MLBFR)<br>* Participants will then perform 50% of tested 1RM for sets of 15, 8, 7, and 7 repetitions on the dominant leg at a pace of 1 repetition every 2 seconds with one-minute rest between sets. Participants will be fitted with an occlusion cuff on the proximal portion of the thigh. The limb occlusion pressure will be set at 60% blood flow occlusion and remain occluded throughout the exercise (Delfi Medical Innovations Personal Tourniquet System).<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Muscle Activation Measured During Traditional High Load Resistance Exercise (HLRE) | Muscle (vastus lateralis) activation will be measured using surface EMG, during the knee extension exercises conducted during the acute HLRE bout. | Measurement will occur during the acute bout HLRE, which will occur during the HLRE study visit. | 
| Low Load Resistance Exercise with Blood Flow Restriction (LLBFR) | Muscle (vastus lateralis) activation will be measured using surface EMG, during the knee extension exercises conducted during the acute LLBFR bout. | Measurement will occur during the acute bout LLBFR, which will occur during the LLBFR study visit. | 
| Moderate Load Resistance Exercise with Blood Flow Restriction (MLBFR) | Muscle activation (vastus lateralis) will be measured using surface EMG, during the knee extension exercises conducted during the acute MLBFR bout. | Measurement will occur during the acute bout MLBFR, which will occur during the MLBFR study visit. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Maximal Voluntary Contraction following HLRE | Maximal Voluntary (isometric) Contractions will be measured using an isokinetic dynamometer before and after the acute HLRE session. | Measurements will be conducted before and immediately following the completion of the HLRE bout. | 
| Change in Maximal Voluntary Contraction following LLBFR | Maximal Voluntary (isometric) Contractions will be measured using an isokinetic dynamometer before and after the acute LLBFR session. | Measurements will be conducted before and immediately following the completion of the LLBFR bout. | 
| Change in Maximal Voluntary Contraction following MLBFR | Maximal Voluntary (isometric) Contractions will be measured using an isokinetic dynamometer before and after the acute MLBFR session. | Measurements will be conducted before and immediately following the completion of the MLBFR bout. |