A fast-rising rehab tool used by physical therapists, athletic trainers and bodybuilders, blood flow restriction (BFR) training has been gaining increasing awareness over the past few years. It holds promise for building muscle strength without lifting heavy weights, and potentially even aiding rehabilitation while resting. Here we will cover the fundamentals of BFR and some science of how it works, to reveal why this technique might become the future of rehab.

What is BFR?

BFR was originally a novel training method developed in Japan by Dr. Yoshiaki Sato in 1966, dubbed as KAATSU (now a BFR product brand). Today BFR is also referred to more scientifically as Occlusion Training, referring to lack of blood flow. The core concept involves using a cuff or band tied tightly around the major arteries in the upper legs or arms. Some of the latest products on the market also embed cuffs into sports clothing for ease of use.

The goal is to temporarily restrict both incoming and outgoing blood flow to the muscle groups (or only outgoing blood flow with KAATSU), essentially to trick the body’s physiological systems into a heightened rehabilitation state. It depends on the protocol, but the typical timeframe for BFR is up to 20-minutes per session. Although it sounds potentially harmful, BFR has been studied extensively and deemed to be safe when used properly.

The most important effect of BFR is that it allows low levels of physical activity to have similar effects to high-intensity exercise. For this reason, low-level resistance exercise, aerobic exercise or physical therapy movements are performed while blood flow is minimized. For resistance exercise, 30% of a person’s maximum load at one rep is the upper limit for triggering the benefits of BFR.

Here is a short practical introduction.

How Does BFR Work?

Although the methodology is relatively straight-forward, the physiological mechanisms of how it works are multifaceted. This is because the body to reacts to the stimulus by kick-starting repairs at a cellular level.  

Here are three cellular response mechanisms which aid rehabilitation.

1. Recovery hormones

When the BFR straps are applied, blood begins to pool in the muscles causing them to swell and become stressed. This triggers the body to produce recovery hormones in the muscle, and when the straps are released, these hormones flood the whole body providing a systemic impact. Every muscle, organ, or structure in the body with a blood supply can potentially benefit from these recovery hormones.

2. Flushing

When the BFR straps are removed after a period of application, the build-up of pressure in the limbs is released, causing a relatively sudden flush that removes waste materials from the joints and muscles. This process is immediate and would typically take the body 48 hours or more to achieve unassisted.

3. Reperfusion

When the BFR straps are removed, fresh nutrient rich blood is driven into the muscles and structural tissues, helping them recover in a process called reperfusion.

Who Uses BFR and What For?

Traditionally the most common application of BFR is to accelerate rehab following severe injuries or operations. In these situations, muscle atrophy is a common problem which can make recovery difficult. When muscles are significantly weakened, biomechanical stress is transferred to the associated joints, which are very easily overloaded. This leads to high-risk of reinjury when trying to get back on the long road to normal activity.

By minimizing muscle loss when unable to deal with load, injury recovery can transition to the next stage of rehabilitation program earlier, from a position of greater strength. BFR can also be used passively (while resting) to harness some of the physiological benefits. This is particularly useful in the first few days following operations, when atrophy begins, but inflammation makes even light training loads infeasible.

Similarly, people who have compromised cardiovascular systems or weak hearts, can use BFR without the obvious risks of high-intensity exercise.

Body builders also find BFR appealing, due to extreme ratio of muscle mass compared to skeletal, joint and tendon mass. As such, performing at maximal loads presents a higher risk injury, with BFR offering a workaround.

Lastly, BFR has recently been making its way from professional sports rehab into performance enhancement of healthy athletes, for both strength and endurance conditioning. A couple of examples of recent adoption are English Premier League clubs and F1 teams.

Overall BFR has been seeing a trend of use growing from practicing physical therapists, orthopedic surgeons, and chiropractors, into the hands of trainers, coaches and elite athletes. Due to the need to control and monitor blood flow precisely, it’s recommended that this technique is used under the supervision of professionally trained personnel.

Takeaway

Although BFR is new to many people, this rehabilitation technique leverages natural biological responses and has been around for decades, with sound science behind it. It can be a valuable method for injury recovery, as well as an aid to performance training. Accordingly, the applied benefits found in clinical applications are now making their way into the human performance domain.

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