Blood flow restriction (BFR) Therapy is the brief and intermittent occlusion of venous (veins) blood flow using a tourniquet-based cuff system that can be placed on either/both your upper and lower extremities while exercising. Using this technique you can exercise with significantly lighter weight while still creating a hypertrophic (muscle growth) and strength response, whereas with traditional strength training a heavy load is required to get a similar strength response.