What is Really Happening During Blood Flow Restriction Therapy?

By Nicholas Rolnick, PT, DPT, MS, CSCS at The Human Performance Mechanic


Did you know that under a certified skilled provider, blood flow restriction therapy (BFR) is easy to use, hard to misuse, safe and BetterFor Results compared to current standards of care? A previous blog post discussed some of the amazing benefits of incorporating blood flow restriction therapy into a rehabilitation program (recommended reading here).

Blood flow restriction therapy increases muscle mass and muscle strength at very low intensities through use of a medical device that restricts blood flow to the arm or leg, increasing muscle oxygen demand. Increases in muscle oxygen demand mean that the muscle has to work harder than normal to generate a muscle contraction, lowering the weight needed to create positive muscular benefits. This has tremendous implications for populations across the board!


People are still curious as to what exactly is happening to our muscles while we resistance train under blood flow restriction. The theory and science behind blood flow restriction therapy are discussed below.


There are two major proposed mechanisms that are believed to significantly contribute to the gains observed in low load blood flow restriction therapy. These are metabolite accumulation and cellular swelling. These are most likely additive exercising under blood flow restriction therapy, but cell swelling can also occur independently (that’s another blog post!).


Metabolite Accumulation:

Each time we contract our muscle, waste products called metabolites is produced. Under normal circumstances, these metabolites (predominantly lactate, or lactic acid) are able to be flushed out of the muscle tissue into the venous system when the muscle relaxes (like after completing a set of exercises). Recall how your muscle “burns” when you complete a set of exercises. That feeling quickly dissipates after you stop exercising. This is the lactate accumulation within your muscle creating that “burn” followed by it being flushed out into the venous system.


When using blood flow restriction, these metabolites cannot be flushed out due to the venous system occlusion. When exercising while your muscles are being occluded, the metabolites interfere with the muscle’s ability to break down glucose, the fuel of our body. This fuel shortage creates increased demand for the muscle at much lower intensities because more of the muscle tissue has to contribute to the contraction! What results with chronic use is muscle mass and strength gains at lower intensities than previously thought possible.


Cellular Swelling:

On the surface of each muscle cell are receptors that sense stretch. When these receptors are stimulated, they signal to the body to increase protein synthesis, leading to muscle mass and strength gains. Think about the “pump” effect following a workout and how that increases the size of your muscles temporarily. Blood flow restriction prevents the blood from leaving your muscles. As you continue to exercise under blood flow restriction, the muscle cell is stretched further and further. Normally the stretch would only last the duration of the exercise (and maybe a short time after), but with blood flow restriction, the muscle cell is consistently stretched, sometimes for up to 10 minutes total! This creates a significant signal for your body to improve muscle mass and strength.


Combined together, metabolic stress and cellular swelling create a powerful stimulus to improve muscle mass and strength. Below is a quick educational video showing blood flow restriction therapy in action and what it can do for your rehabilitation:

Blood flow restriction therapy is a proven safe therapy.  In the hands of a certified skilled provider, it can accelerate the return to full function so you can get back to the things you love to do faster than traditional care. 

You can find and schedule a physical therapy appointment with thousands of quality physical therapy clinics on the BetterPT website and BetterPT mobile app. You no longer need a doctor prescription to start physical therapy, you can utilize direct access and schedule an appointment within minutes.

Experience the joy of pain-free movement with the proven therapy of blood flow restriction and start feeling BETTER today!

Nicholas Rolnick PT, DPT, MS, CSCS graduated with his DPT from Columbia University with academic honors. Prior to Columbia, Nicholas Rolnick PT, DPT, MS, CSCS earned a Masters degree in Health Promotion Management from American University. His Mission at The Human Performance Mechanic is to help everyone experience the Joy of Pain-Free Movement through world class Physical Therapy & Personal Training.


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