Blood Flow Restriction (BFR) Training

In traditional fitness training, growing stronger bigger muscles requires long sessions at the gym, performing multiple sets of exercises using heavy resistance. The art of bodybuilding for strength and hypertrophy is centuries-old, and while modern exercise science has made significant inroads in quantifying optimal training loads and refining exercise technique, not much has changed over time. Consistent training at about 65 percent or more of one-rep-max is the commonly used recipe to enhance muscle size, strength and definition.

From a sports injury rehab perspective, restoring muscle strength and size poses challenges when preparing an athlete for return to play. An injured athlete may be unable to endure high training volumes, slowing down the rehab process and delaying recovery. Now, blood flow restriction training, a promising new approach to increasing muscle strength and size at much lower training volumes, has opened new doors for athletes and fitness enthusiasts who want to gain strength and muscle mass.

Building Muscle Size and Strength

Overload is the underlying principle of all fitness training. When you challenge your body to perform at levels to which it is unaccustomed, adaptations take place to help you meet future challenges. In the case of muscle tissue, resistance training loads and stretches the muscle’s sarcomeres, causing mild damage to the muscle fiber. During recovery, your body repairs the damaged tissue and fortifies it to meet similar training loads in the future. During the recovery phase, you may experience muscle soreness and elevated levels of certain chemicals and hormones, both of which go away over the course of a few days.

Blood flow restriction therapy provides a way to increase muscle size and strength at much lower training volumes — as low as 20 to 30 percent of one-rep-max, as opposed to the traditional 65 percent. For example, if you can bench press 200 pounds only one time, your traditional training volume would be 65 percent of 200, or about 130 pounds. With blood flow restriction training, you will be able to elicit similar adaptations in muscle size and strength with much less weight, using only about 40 to 60 pounds.

How Blood Flow Restriction Training Works

Your muscles are made up of two types of muscle fiber — Type I slow twitch and Type II fast twitch.


Type I muscle fibers are good for endurance activities, and rely heavily on oxygen to repeatedly contract. Type I fibers generate comparatively low levels of force and are smaller and darker in color than Type II, but they can contract repeatedly without fatigue, as long as training intensity is low and oxygen is in ample supply. Type I fibers are well suited to long-duration activities like walking, running, cycling or swimming.

Type II muscle fibers are larger and lighter in color — think chicken breast vs thigh. They produce high levels of force but fatigue quickly because they rely on phosphocreatine (PCr), which the body produces in limited supply. When PCr reserves are depleted, the muscle quickly reaches volitional fatigue, and cannot continue to contract until PCr is replenished, which takes a minute or two while the muscle rests. Type II muscle fibers are best suited to high-intensity training, like sprinting or weight lifting.

The theory behind blood flow restriction training is that by limiting oxygen flow during exercise, Type I muscle fibers are deactivated, forcing Type II fibers to do the heavy lifting. But there’s more to it than that. Lactate is a byproduct of muscle contraction and a precursor to growth hormone release and muscle protein synthesis. After BFR training, growth hormone secretion is as much as 170 percent higher than after traditional resistance training.

Because BFR uses significantly less weight, damage to muscle fibers is limited, while protein synthesis is enhanced. By deactivating Type I fibers, gains in muscle strength and size can be achieved with much lower training loads.

How Blood Flow Restriction is Achieved

BFR training uses tight cuffs or bands, applied to the upper arm or upper leg, to limit blood flow during an exercise set. It is important to note that only those two sites are considered safe for applying blood flow restriction bands. Using them elsewhere can cause nerve damage.


Some blood flow restriction training bands allow you to measure occlusion pressure precisely. It is recommended to use 80% occlusion for the lower body, and 50% for the upper body. When using BFR straps that do not measure pressure, use a rating of discomfort scale of four to five out of 10 for the upper body, and six to eight out of 10 for the lower body.

BFR training can be applied to almost any type of exercise.

  • A typical BFR training protocol is one set of 30 repetitions, followed by three sets of 15 repetitions, or 30/15/15/15, for a total of 75 reps.
  • Reps should be performed slowly, taking about 2 second each for concentric and eccentric contraction phases.
  • Allow a full 30 seconds’ rest between exercise sets.

Blood Flow Restriction Physical Therapy

BFR training offers injured athletes a means of restoring muscle strength and size without having to use large training loads, sparing soft tissues from further damage. When incorporated into a physical therapy rehabilitation program, BFR can help the athlete recover fully, and reduce the risk of injury upon return to play.

The sports medicine team at NYDNRehab is dedicated to restoring function and enhancing performance in athletes, fitness enthusiasts and anyone suffering from injury or motor disorders. We use the latest technologies and innovative treatment approaches to help you get back to doing the things you love. Contact us today!

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In this instance, an athlete was originally diagnosed with minor quadriceps muscle strain and was treated for four weeks, with unsatisfactory results. When he came to our clinic, the muscle was not healing, and the patients’ muscle tissue had already begun to atrophy.

Upon examination using MSUS, we discovered that he had a full muscle thickness tear that had been overlooked by his previous provider. To mitigate damage and promote healing, surgery should have been performed immediately after the injury occurred. Because of misdiagnosis and inappropriate treatment, the patient now has permanent damage that cannot be corrected.

The most important advantage of Ultrasound over MRI imaging is its ability to zero in on the symptomatic region and obtain imaging, with active participation and feedback from the patient. Using dynamic MSUS, we can see what happens when patients contract their muscles, something that cannot be done with MRI. From a diagnostic perspective, this interaction is invaluable.

Dynamic ultrasonography examination demonstrating
the full thickness tear and already occurring muscle atrophy
due to misdiagnosis and not referring the patient
to proper diagnostic workup

Demonstration of how very small muscle defect is made and revealed
to be a complete tear with muscle contraction
under diagnostic sonography (not possible with MRI)


Complete tear of rectus femoris
with large hematoma (blood)


Separation of muscle ends due to tear elicited
on dynamic sonography examination

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