Blood Flow Restriction (BFR)

Muscle atrophy (loss of muscle mass) and muscle weakness are among the most common impairments that physical therapists treat. Muscle atrophy can be caused by a number of issues, such as malnutrition, neurological conditions, and de-conditioning/disuse. 

Disuse atrophy occurs quickly (within the first 2 weeks) and is very prevalent following injury or surgery. For example, an individual recovering from an ACL reconstruction surgery will likely show visible differences in quad and calf muscle size. The same occurs for an individual after an ankle sprain, meniscus tears/surgery, fracture, prolonged tendonitis, shoulder surgery, etc. 

One of the challenges with addressing muscle atrophy is finding the right exercise intensity to create muscle gains without overtaxing the healing joints, fascia, and soft tissue. For example, it is not safe for an individual who had ACL reconstruction surgery 4 weeks ago to perform loaded squats and jumping exercises because the new ligament is not fully prepared to handle these loads. During this phase, individuals often get frustrated by the slow strength gains. 

In comes blood flow restriction training! Blood flow restriction (BFR) “is a training method partially restricting arterial inflow and fully restricting venous outflow in working musculature during exercise.” BFR training uses a tourniquet or medical cuff to restrict blood flow up to 50% for the upper body or 80% for the lower body. BFR dates back to Dr. Yoshiaki Sato in Japan in the 1960’s and became part of the physical therapy scope of practice in 2018. The restriction in blood flow causes a low oxygen (hypoxic) state, which triggers greater muscle activation, fatigue, and anabolic signaling than the same exercise without the use of BFR.

Long story short, BFR allows individuals to work out at a lower intensity/resistance, but reap the benefits of a high intensity workout. Typical resistance training for hypertrophy (increased muscle mass) requires loading at >60% of your 1 rep max. Again, these loads may not be safe for patients following surgery, or they may not be tolerable for someone with chronic pain such as tendonitis. BFR training involves low intensity exercises, usually with just body weight or 20-40% of your 1 RM. 

When used according to researched protocols, BFR training is safe and effective. As always, you should be cleared by a medical provider familiar with BFR before using it.

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Lorenz DS, Bailey L, Wilk KE, Mangine RE, Head P, Grindstaff TL, Morison S; Blood Flow Restriction Training. J Athl Train 1 September 2021; 56 (9): 937–944. doi: https://doi.org/10.4085/418-20

Patterson SD, Hughes L, Warmington S, et al. Blood Flow Restriction Exercise: Considerations of Methodology, Application, and Safety.Front Physiol. 2019;10:533. Published 2019 May 15. doi:10.3389/fphys.2019.00533