is a strength training technique that involves partially restricting the flow of blood into and out of a limb while exercising. While the blood flow is restricted, exercise is performed using a significantly lighter weight than what would be used without BFR. When performing resistance exercise, somebody typically needs to use a weight that is about 70-80% of the highest weight that they can perform for 1 repetition of that specific exercise (1 rep max or 1RM) in order to make any significant improvement in strength or muscle hypertrophy. When using BFR, only 20-30% of the person’s 1RM is necessary to elicit similar effects and benefits.

While restricting blood flow to a limb during exercise may initially sound dangerous and counter-intuitive, extensive research has shown that this is a safe and effective tool when applied properly by a trained health care professional to the appropriate patient population. In fact, it is common during orthopedic surgeries for 100% of blood flow to be occluded in a limb for extended periods of time. During BFR exercise, the maximum restriction that will be used is 80%, and this will typically be applied for 5-15 minutes at a time.

Partial restriction of blood flow to the limb is achieved using a specialized pneumatic cuff that is placed on the exercising limb as close to the trunk as possible. This cuff is inflated to a specific pressure that is unique to both the individual who is exercising, and the limb that they are using for the exercise. This unique pressure is calculated using a handheld Doppler ultrasound along with protocols that have been proven in the research to be both the safest AND most-effective. When the appropriate pressure has been reached, this will partially restrict the blood flow into the limb, and completely occlude venous blood flow back from the limb. When exercise is performed under these conditions, oxygen within the muscle is used up rapidly and is unable to be replenished due to the restricted blood flow. Due to the occlusion of venous return from the muscle, this also causes a buildup of lactic acid within the muscle that is unable to be flushed out of the tissues. When this occurs, there is a strong perception of muscle fatigue that would typically not occur using the same reduced resistance without any restriction of blood flow. These conditions also cause a systemic release of Human Growth Hormone (HGH) and a localized increase in muscle protein synthesis which contribute to tissue healing and muscle growth.

This intervention is particularly useful in Physical Therapy, as many patients who come to PT are either * not allowed to load an exercise heavily (after surgery or injury) * unable to tolerate heavy loading due to pain. Using BFR allows patients to perform exercises with less resistance, less mechanical stress to the muscle, and less pain. This means that they can achieve significant strength gains and muscle growth, or prevent muscle atrophy, even while they heal from their surgery or injury!