Blood Flow Restriction Training in Physical Therapy

Improved Strength Gains During Rehabilitation

Blood flow restriction (BFR) training is a strengthening technique occasionally used in physical therapy clinics to help gain muscle function after an injury or surgery. It is done by temporarily restricting blood flow to a muscle during exercise.

Blood pressure cuff close up
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This method is most appropriate when high training loads are not appropriate, such as after surgery, injury, or in cases of significant loss of muscle mass. Blood flow restriction strengthening uses low-intensity exercise to achieve strength gains typically seen with high-intensity training.

BFR is a newer type of physical therapy (PT) treatment. Early research indicates that it may lead to adequate strength gains with low-intensity exercise.

How Does BFR Training Work?

Blood flow restriction training was developed in the 1960s in Japan as a low-intensity strengthening regimen called KAATSU. It involves using a tourniquet or pneumatic cuff around a muscle during low intensity, high repetition muscle contractions.

It has been gaining popularity in fitness programs, and more recently it has become more and more popular in physical therapy clinics. Why? Because it allows for high muscle strength and growth gains with low-intensity exercise.

Blood flow restriction training places a muscle under mechanical stress. (This mechanical stress also occurs during high-intensity muscle strengthening.) The result of this high stress helps improve muscle hypertrophy, or growth, via:

  • Release of hormones specific to muscle growth
  • Activation of specific stem cells for muscle growth
  • Cell swelling within muscles
  • Hypoxia (decrease in oxygen)

While these factors occur during high load training, they may be achieved during low load training by restricting blood flow to the muscle. This restriction creates an environment where muscle growth can occur even if the training loads are kept to a minimum, something that may be important after injury or surgery.

As your body is healing after surgery, you may not be able to place high stresses on a muscle or ligament. Low load exercises may be required, and blood flow restriction training allows for maximal strength gains with minimal, and safe, loads.

Performing BFR Training

Before starting blood flow restriction training, or any exercise program, you must check in with your physician to ensure that exercise is safe for your condition. Your physical therapist may be able to teach you how to properly perform BFR exercises.

Equipment Needed

To perform blood flow restriction exercise, you must obtain a specialized pneumatic cuff that will be used to occlude blood flow to your muscle. A blood pressure cuff may be used.

Blood flow restriction training cuffs are also available for purchase. These specialized cuffs may be contoured to fit specific body parts, like thighs, calves, or upper arms.

How to Do It

To perform BFR training:

  1. Place the cuff around your muscle to be strengthened.
  2. Pump the cuff up to the desired pressure, usually about 180 millimeters of mercury (mmHg), or 1.5 times your resting systolic blood pressure.
  3. Contract the muscle to be strengthened. For example, if strengthening your quadriceps muscle, place the cuff around your thigh, pump it up, and perform a quad set of short arc quad.
  4. Hold the contraction for 5 seconds.
  5. Release the contraction.
  6. Repeat slowly for 15 to 20 repetitions.

Your physical therapist may have you rest for 30 seconds and then repeat another set. Blood flow restriction training is supposed to be low intensity but high repetition, so it is common to perform two to three sets of 15 to 20 reps during each session.

When the exercise is complete, you should remove the cuff and allow for normal blood flow to return to your muscle. Your muscle may be red, and it may also feel tight and "full" after BFR training.

Conditions Treated

Any muscle or muscle group that is weak after injury, illness, or surgery may benefit from blood flow restriction training. This may include:

  • Muscle strains
  • Generalized weakness
  • Hip, knee, or ankle surgery where weakness is present
  • Upper extremity surgery where weakness is present
  • After upper or lower extremity fracture
  • Neurological conditions where weakness is present

Any condition that results in weakness and requires low-intensity exercise to protect fragile or healing tissues may benefit from blood flow restriction training.

Blood Flow Restriction Research

Does science support the use of blood flow restriction training after injury? Perhaps.

A 2017 meta-analysis (research of multiple published studies) found that BFR training was superior in gaining strength in patients with various conditions such as anterior cruciate ligament repair and knee osteoarthritis when compared to low-intensity exercise alone. The researchers also found that the risk of injury was minimal when correct applications of blood flow restriction training was done.

Another study examined the effect of BFR training on older adults. The researchers examined 11 published studies and found that low intensity training with blood flow restriction was a safe method to help older adults gain muscle strength and growth. Again, no risks were found when the exercise was done appropriately.

Negative Side Effects

There may be negative undesired side effects of blood flow restriction training, especially when not performed properly. These may include:

The best way to avoid negative side effects of BFR training is to work closely with a physical therapist who is trained in the proper application of the exercise regimen.

Who Should Not Do BFR Training?

People with certain conditions should not engage in BFR training, as injury to the venous or arterial system may occur. Contraindications to BFR training may include:

Before performing any exercise, it is important to speak with your physician and physical therapist to ensure that exercise is right for you.


If you have any muscle weakness from an injury, illness, or surgery, you may benefit from PT to help improve your strength and overall functional mobility. Blood flow restriction training is one method your physical therapist may use to quickly and safely improve muscle strength with low intensity exercise. This may help you return to your previous level of function quickly and safely.

2 Sources
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  1. Hughes L, Paton B, Rosenblatt B, Gissane C, Patterson SD. Blood flow restriction training in clinical musculoskeletal rehabilitation: a systematic review and meta-analysis. Br J Sports Med. 2017;51(13):1003-1011. doi:10.1136/bjsports-2016-097071

  2. Centner C, Wiegel P, Gollhofer A, König D. Effects of blood flow restriction training on muscular strength and hypertrophy in older individuals: A systematic review and meta-analysis. Sports Med. 2019;49(1):95-108. doi:10.1007/s40279-018-0994-1

By Brett Sears, PT
Brett Sears, PT, MDT, is a physical therapist with over 20 years of experience in orthopedic and hospital-based therapy.