Personalized Blood Flow Restriction: The Future of Rehabilitation
In the last few years, there has been a shift in the approach minimizing muscle loss and stimulating strength gains in athletes after injury. Traditional strengthening guidelines tell us that we need to lift 75-85% of a one repetition maximum to achieve positive strength and hypertrophy changes. After acute injury, post-operatively, or with overuse injury, this heavy mechanical tension model is something that is not typically tolerated by patients. Blood flow restriction rehabilitation seems to be a way to stimulate similar muscle adaptation to heavy load while using the light loads that are available to us in post-injury management.
Anabolic resistance is defined as the condition in which a limb in a period of disuse, such as after surgery or injury, reduces protein synthesis specifically within that limb. (Glover et al 2008) The reduction in local protein synthesis is linked to atrophy and decreased strength. Light load exercises have little to no effect on increasing protein synthesis, but light load combined with BFR consistently shows increased protein synthetic responses in literature. For instance, Fujita et al demonstrated a 46% rise in protein synthesis 3 hours post training with BFR at low loads. A work matched control group without occlusion demonstrated no change. (Fujita et al 2007)
How Does BFR Work?
BFR uses a specialized tourniquet system to limit arterial inflow and occlude venous outflow of an exercising limb. The hypoxic environment created, stimulates strength and hypertrophy gains at a much lighter load. Although the exact mechanism behind BFR training is still not fully understood, several potential mechanisms have been put forward. One prevailing hypothesis is the recruitment of larger fast twitch motor units secondary to the hypoxic state created by the tourniquet. To support this, several papers have demonstrated higher iEMG signal output when performing exercise under vascular occlusion compared to low load training. (Yasuda et al 2009, Wilson et al 2013) As muscle utilizes the anaerobic pathway during resistance training, the metabolic accumulation within the muscle may be a trigger for hypertrophic changes. (Schoenfeld 2013) This can be seen when comparing the accumulation of substances such as lactate in BFR vs low load training. In the BFR group, there is a significant rise in lactate which is a byproduct of anaerobic metabolism and the levels of metabolic stress measured via lactate is similar between BFR and HIT training. (Poton et al 2014) The systemic response from this metabolite accumulation with BFR training includes significant increases in substances such as Growth Hormone (Takarada et al 2000, Pierce et al 2006), Insulin Like Growth Factor, (Abe et al 2005) Myogenic Stem Cells (Nielson et al 2012) and down regulation of substances such as Myostatin. (Laurentino et al 2012)
Personalized BFR (PBFR) refers to BFR exercise applied at a target percentage of someone’s limb occlusion pressure (LOP). Everyone’s pressure is going to be different based on race, gender, limb circumference, tissue density, blood pressure, cuff type, and placement of the cuff. The only way to account for all of those variables is to take a measurement of LOP. It is also becoming more apparent that the pressure used for BFR can significantly affect the outcome of the exercise. Fatela et al showed significantly higher iEMG for Rectus Femoris and Vastus Medialis with 80% occlusion performing knee extension compared to 40% or 60% occlusion (Fatela 2016). PBFR is intended to maximize the effects of BFR exercise while using the least amount of pressure necessary, thus increasing safety for soft tissue structures like nerves under the pressure of the cuff.
The Leader in PBFR Education
Johnny Owens, MPT founded Owens Recovery Science after utilizing the application of PBFR within a military setting. Owens is the former Chief of Human Performance Optimization at the Center for the Intrepid (CFI), which is part of the SAMMC Department of Orthopedics and Rehabilitation (DOR). Johnny was at SAMMC for 10 years, treating service members suffering severe musculoskeletal trauma. These traumatic injuries required a new approach to strengthening since lifting heavy weight was not available. Johnny has been applying Personalized Blood Flow Restriction clinically since 2012 and developed an educational program centered around best practices for clinicians looking to add PBFR to their repertoire. The course is an EBP course that addresses history, safety, cellular physiology, and practical application for the rehab professional.
Abe T, Yasuda T, Midorikawa T, et al. Skeletal muscle size and circulating IGF-1 are increased after two weeks of twice daily KAATSU resistance training. Int J Kaatsu Train Res. 2005;1: 6–12.
Fatela, Pedro, et al. "Acute effects of exercise under different levels of blood-flow restriction on muscle activation and fatigue." European journal of applied physiology 116.5 (2016): 985-995.
Fujita, S., Abe, T., Drummond, M. J., Cadenas, J. G., Dreyer, H. C., Sato, Y., et al. (2007). Blood flow restriction during low-intensity resistance exercise increases S6K1phosphorylation and muscle protein synthesis. J. Appl. Physiol. 103, 903–910.
Glover, Elisa I., et al. "Immobilization induces anabolic resistance in human myofibrillar protein synthesis with low and high dose amino acid infusion."The Journal of physiology 586.24 (2008): 6049-6061.
Laurentino, G. C., Ugrinowitsch, C., Roschel, H., Aoki, M. S., Soares, A. G., Neves, M., Jr., Tricoli, V. (2012). Strength training with blood flow restriction diminishes myostatin gene expression. MedSci Sports Exerc, 44 (3), 406-412.
Nielsen, J. L., Aagaard, P., Bech, R. D., Nygaard, T., Hvid, L. G., Wernbom, M., . Frandsen, U. (2012). Proliferation of myogenic stem cells in human skeletal muscle in response to low-load resistance training with blood flow restriction. J Physiol, 590 (Pt 17), 4351-4361. 773–782.
Pierce, J. R., Clark, B. C., Ploutz-Snyder, L. L., & Kanaley, J. A. (2006). Growth hormone and muscle function responses to skeletal muscle ischemia. J Appl Physiol,101 (6),1588-1595. doi:10.1152/japplphysiol.00585.2006.
Poton, R., & Polito, M. D. (2014). Hemodynamic response to resistance exercise with and without blood flow restriction in healthy subjects. Clin Physiol Funct Imaging . doi:10.1111/cpf.12218.
Schoenfeld, B. J. (2013). Potential mechanisms for a role of metabolic stress in hypertrophic adaptations to resistance training. Sports Med, 43 (3), 179-194. doi: 10.1007/s40279-013-0017-1
Yasuda, T., Brechue, W. F., Fujita, T., Shirakawa, J., Sato, Y., & Abe, T. (2009). Muscle activation during low-intensity muscle contractions with restricted blood flow. J Sports Sci, 27 (5), 479-489. doi: 10.1080/02640410802626567
Wilson JM, Lowery RP, Joy JM, Loenneke JP, Naimo MA. Practical blood flow restriction training increases acute determinants of hypertrophy without increasing indices of muscle damage. J Strength Cond Res 2013;27:3068–75.