Blood Flow Restriction (BFR) Exercise : what it is & how it works
The use of BFR has increased in popularity over the past decade, particularly for its promising application in physical therapy. And rightfully so! Research supporting the use of BFR as an effective and safe tool is strong and growing.
BFR was first introduced in Japan in 1966 and became popularized as “Kaatsu training”. It is now backed by decades of research. It was not until the early 2000s when tubes and wraps were replaced with “air cuffs”.
BFR utilizes specialized wider than normal pneumatic cuffs to allow arterial blood flow to a region while restricting venous return. BFR is not occlusion training. Occlusion training involves completely stopping blood flow into an extremity for significant periods of time which can damage tissue or nerves and increases the risk for medical conditions like DVTs and permanent muscle fiber death.
The most common question when explaining BFR to those unfamiliar with the technique is: why would I want to do this?
When venous return is limited, there is an accumulation of metabolic byproducts such as lactate. Lactate is needed as a buffering agent for the high concentration of hydrogen ions released during the hydrolysis of ATP, especially at higher absolute or perceived intensities of exercise.
The accumulation of the metabolic byproducts leads to an increased acidic environment within the muscle. This disturbance of homeostasis begins a cascade of events that leads to an optimal anabolic environment. Increases in anabolic hormones like growth hormone and IGF-1 impact the signaling pathways that control protein synthesis (mTOR and mTORc1). Ultimately, this will lead to skeletal muscle hypertrophy over time.
In addition, BFR with exercise makes it more difficult to recruit Type I muscle fibers and the threshold for recruiting Type II fibers (our main strength and power muscle fibers) is lowered. This leads to a recruitment pattern opposite of the traditional “size principle of fiber recruitment.”
Typically, the above beneficial anabolic environment and physiological adaptations are only achieved during high intensity and high volume strength training. But associated with this type of training is the risk of muscle breakdown, joint stress, and non-contractile tissues.
BFR is very effective for things like tennis elbow, ankle sprains, tendonitis (biceps, achilles, patellar- just to name a few).
During periods of non-weight bearing, like after an ankle sprain, BFR has been shown to be highly effective at reducing atrophy and loss of strength and muscle mass which could speed up the transition to full weight-bearing status.