Blood Flow Restriction (BFR) training
Blood Flow Restriction (BFR) training is a technique that combines low intensity exercise with blood flow occlusion that produces similar results to high intensity training. It has been used in the gym setting for some time but it is gaining popularity in clinical settings.
Muscle weakness commonly occurs in a variety of conditions and pathologies. High load resistance training has been shown to be the most successful means in improving muscular strength and obtaining muscle hypertrophy (a growth and increase in muscles cells). The problem is that for most of our post-operative patients, high load and high intensity exercises may not be clinically appropriate. Orthopedic surgery, chronic pain, muscle or joint injury, tendonitis and/or arthritis could potentially benefit from muscle strengthening and muscle hypertrophy but cannot tolerate high intensity/ loaded exercises.
BFR training was initially developed in the 1960’s in Japan. It involves the application of a pneumatic cuff (tourniquet) proximally to the muscles that are being trained. It can be applied to either the upper or lower limb. The cuff is then inflated to a specific pressure with the aim of obtaining partial arterial and complete venous occlusion. The patient is then asked to perform resistance exercises at a low intensity of 20-30% of 1 repetition max (1RM), with high repetitions per set (15-30) and short rest intervals between sets (30 seconds)
Muscle tension and metabolic stress are the two primary factors responsible for muscle hypertrophy. When a muscle is placed under mechanical stress, the concentration of anabolic horomone levels increase. The activation of myogenic stem cells and the elevated anabolic hormones result in protein metabolism and allow muscle hypertrophy to occur. Release of hormones, hypoxia and cell swelling occur when a muscle is under metabolic stress. These factors are all part of the anabolism of muscle tissue.
The aim of BFR training is to mimic the effects of high intensity exercise by recreating a hypoxic environment using a cuff. Because the outflow of blood is limited using the cuff, capillary blood that has low oxygen content collects and there is an increase in protons and lactic acid. The same physiological adaptations to the muscle (eg release of hormones, hypoxia and cell swelling) will take place during the BFR training and low intensity exercise as would occur with high intensity exercise.