bfr and muscle mitochondrial oxidative capacity

Conditions: Mitochondria; Strength; Hypertrophy

Summary: blood flow restricted (bfr) exercise has been shown to improve skeletal muscle adaptations to resistance exercise. bfr uses blood pressure cuffs (i.e., tourniquets) to reduce skeletal muscle blood flow during resistance exercise. one benefit of bfr is that skeletal muscle adaptations to resistance exercise training including muscle hypertrophy and increases in strength can be achieved at lower-loads (e.g., 25-30% 1rm), that are often comparable to more traditional resistance training loads (70-85% 1rm). however, the impact that low-load bfr resistance exercise has on muscle quality and bioenergetics is unknown. the present study will examine the impact of 6 weeks of low-load, single-leg resistance exercise training with or without personalized bfr on measures of muscle mass, strength, quality, and mitochondrial bioenergetics. the investigators will recruit and study up to 30, previously sedentary, healthy, college-aged adults (18-40 years). the investigators will measure muscle mass using dual energy x-ray absorptiometry and muscle strength and endurance using isokinetic testing. the investigators will normalize knee extensor strength to lower limb lean mass to quantify muscle quality. the investigators will also use near infrared spectroscopy (nirs) to measure mitochondrial oxidative capacity in the vastus lateralis. finally, the investigators will measure markers of systemic inflammation and markers of muscle damage using commercially available elisa assays.


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 inclusive 4. body mass index (bmi) between 18.5-30 kg/m2 inclusive 5. no medical condition that would limit their participation in supervised exercise training based on the physical activity readiness questionnaire for everyone (parq+) 6. no current prescription medications, with the exception of birth control 7. willing to allow researchers to use data, biospecimens (e.g., blood) and images (e.g., dual energy x-ray absorptiometry) for research purposes after study participation is completed exclusion criteria. 1. evidence or self-report being pregnant, lactating, or anticipating becoming pregnant in the next year 2. participation in resistance or aerobic exercise training \> 2 days per week within the 3 months prior to screening 3. self-report of history of type 1 or 2 diabetes mellitus 4. self-report history of cardiovascular, peripheral vascular, cerebral vascular, pulmonary, or renal disease 5. self-report or evidence of uncontrolled hypertension 6. self-report history of blood clotting disorders 7. self-report history of deep vein thrombosis or pulmonary embolism 8. self-report history of sickle cell trait 9. self-report history of varicose veins 10. self-report history of a myopathy leading to muscle loss, weakness, severe cramps or myalgia 11. self-report history of orthopedic limitations that would preclude them from participation in a dynamic exercise program 12. self-report history of musculoskeletal disorders (e.g., severe osteoarthritis, rheumatoid arthritis, avascular necrosis or osteonecrosis) 13. self-report history of neurological disorders (e.g., peripheral neuropathy, amyotrophic lateral sclerosis, multiple sclerosis, fibromyalgia, parkinson's disease) 14. weight loss of \> 10% in the last 3 months prior to screening 15. active smoking 16. current consumption of \> 14 alcoholic drinks per week based on self-report 17. absolute contraindication to exercise as defined by the american college of sports medicine,1 including: 1. resting diastolic blood pressure \> 100 mm hg 2. resting systolic blood pressure \> 180 mm hg 3. resting heart rate \> 100 beats per min 18. self-report acute viral or bacterial upper or lower respiratory infection at screening 19. 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