Muscle Activation With Acute Bouts of Blood Flow Restricted Resistance Exercise

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).


Eligibility Criteria:
Inclusion Criteria:

1. Capable and willing to give written informed consent
2. Capable of understanding inclusion and exclusion criteria
3. 18-40 years of age
4. A waist circumference \< 40 inches.
5. No medical condition that would limit their participation in supervised exercise sessions based on the Physical Activity Readiness Questionnaire for Everyone (PARQ+)
6. No current prescription medications
7. Willing to allow researchers to use data and images (e.g., Dual Energy X-Ray Absorptiometry) for research purposes after study participation is completed
8. 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:

1. Self-report history of diabetes mellitus
2. Self-report history of cardiovascular, peripheral vascular, cerebral vascular, pulmonary, or renal disease
3. Self-report or evidence of uncontrolled hypertension \> 150/85 (or measured)
4. Self-report history of blood clotting disorders
5. Self-report history of deep vein thrombosis or pulmonary embolism
6. Self-report history of sickle cell trait
7. Self-report history of varicose veins
8. Self-report history of a myopathy leading to muscle loss, weakness, severe cramps or myalgia
9. Self-report history of orthopedic limitations that would preclude them from participation in a dynamic exercise program
10. Self-report history of musculoskeletal disorders (e.g., severe osteoarthritis, rheumatoid arthritis, avascular necrosis or osteonecrosis)
11. Self-report history of neurological disorders (e.g., peripheral neuropathy, amyotrophic lateral sclerosis, multiple sclerosis, fibromyalgia, Parkinson's disease)
12. Weight loss of \> 10% in the last 3 months prior to screening
13. Active tobacco use including smoking, vaping, or smokeless tobacco use
14. Current consumption of \> 14 alcoholic drinks per week based on self-report
15. 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