Blood Flow Restriction Training

Personalized Blood Flow Restriction Training is a technique that can be used to perform exercises with a reduced amount of blood flow to the arm or leg.  This is often performed by using an approved cuff or strap placed tightly around the limb to reduce, but not completely obstruct, blood flow.  The benefit of blood flow restriction training is to allow the person to exercise with lower intensity, yet still have the benefits of high-intensity training.  BFR research has been going on for over 20 years!


How Do Muscles Get Stronger?

It’s probably a good idea to start with the basics on how muscles get bigger and stronger.  Muscles adapt through neural, mechanical, and metabolic mechanisms.  Many of these mechanisms involve multi-step pathways.  Put most simply, improving strength comes down to load and volume.

From a hormonal standpoint, testosterone increases with high load, multi-joint exercises, while growth hormone increases with high volume, multi-joint exercises.  High volume, moderate intensity increases growth hormone, but low volume, high intensity has no growth hormone response.

Insulin-like growth factors (IGF’s), myogenic stem cells (MSC’s), Vascular Endothelial Growth Factor (VEGF), and the mTORC1 pathway are all activated during normal high-load training.  Notice that the key term above is “high load.”  We need high loads to get strong.  All of these various pathways and “ingredients” are vital for muscle growth.


How Does Blood Flow Restriction Training Work?

There are a number of proposed mechanisms for how BFR works.  The medical professions current understanding is that blood flow restriction training works by the indirect effect of metabolite accumulation and the hypoxic environment from exercising with limited arterial flow.  This causes greater fatigue, muscle activation, and also anabolic signaling pathways that lead to muscular adaptations compared to exercise without BFR.

Therefore, if we know that getting strong requires a combination of load and volume, what do we do in cases where people are not appropriate for high loads or can’t tolerate them?  For example, following an injury or surgery.  Or maybe with someone training at home without access to weights to accomplish high loads.  This is where BFR training can be helpful!  Blood flow restriction training can be a tremendous adjunct to training because these same muscle building ingredients happen in the low-load environment.

In cases of immobilization or atrophy, muscle protein degradation takes place.  With BFR training using low loads, and in some studies no load at all, multiple pathways are activated to increase muscle protein synthesis.  The hypoxic environment and the mechanisms associated with it causes a “snowball effect.”  The reduced oxygen in the area accelerates fatigue and recruitment of more-high threshold motor units.  The lowered pH from the hypoxic environment is a hypertrophic stimulus.  There is also an added benefit of the “muscle pump” from cellular swelling.  In effect, the compression causes metabolites to accumulate.  Essentially, when the compression is reduced or relieved, the flood gates essentially open, bringing all those “muscle building ingredients” to the muscle.


Blood Flow Restriction In Physical Therapy

No matter what injury you’re dealing with, muscle atrophy and weakness is a common impairment.  Methods to address these impairments are often performed right away.  Neuromuscular electrical stimulation, biofeedback, and isometrics are just a few methods physical therapists use to start strengthening early while the tissue is compromised.  Unfortunately, in the early healing phases, heavy loads are not appropriate because it may overload or damage the healing tissue.  This becomes an issue when someone is trying to recover from an injury and gain strength at the same time.

Resistance training guidelines encourage high loads that are more than 60% of one maximal repetition (1RM) for 8-12 repetitions.  We need proper loads to get the adaptations we seek.  Further complicating matters is that 1RM testing in the early phases of rehabilitation isn’t appropriate.

BFR provides a safe option for limiting atrophy following injury by increasing strength in a low-load environment.  Typically, BFR training loads are 20-30% 1RM with 15-30 repetitions per set.  This is much more applicable to training with healing tissue that is not yet ready to accept more intense loading.


Does Blood Flow Restriction Training Work?

Numerous research has been published documenting the effectiveness of BFR training.  Blood flow restriction training has been shown to help limit atrophy, enhance hypertrophy, increase strength, and improve aerobic capacity, all in a low-load environment.


 Is Blood Flow Restriction Training Safe?

Before we dig into safety, it’s important to note that anything can potentially be unsafe in the wrong hands or when used inappropriately or in the wrong population.  That being said, BFR training has been shown to be safe.  Pivot’s physical therapists who utilize BFR in practice are highly trained and certified in this technique.

BFR has been used in a variety of musculoskeletal pathologies and to date, has not resulted in serious adverse events.  Common side effects with BFR training are often short-lived and include symptoms such as numbness, light bruising, discomfort, skin abrasions, and delayed onset muscle soreness (DOMS).  At this time, we recommend that BFR training commence about two weeks after surgery to help reduce the risk of adverse events.  Pivot’s physical therapists will discuss best practices with your referring physician before initiating BFR therapy.


What Are The Contraindications To BFR Training?

Based on the above safety guidelines, the contraindications to BFR are centered around those with vascular insufficiencies or cardiac implications.  People with hypertension, diabetes, history of stroke or DVT, cardiac disease, active infections, pregnancy, clotting disorders, or other vascular insufficiencies (like varicose veins) are contraindications.  That being said, it is advised you speak with your primary care or overseeing care physician to determine if you are appropriate for BFR training.

In conclusion, Pivot Physical Therapy provides the advanced technique Blood Flow Restriction Training.  Many of our expert level therapists are highly trained in this technique and are certified by the nation’s top clinical education companies.  BFR is a safe technique that is designed to begin strengthening sooner while your tissues are still healing and accelerate your rehab process for exceptional results.

Contact your local Pivot Physical Therapy clinic today to learn more about BFR and how it may be right for your road to recovery.


Author: Chris Roosa, DPT, OCS, MTC, CMTPT, PRC, FPS

Pivot Physical Therapy Vice President of Clinical Services