How Does Blood Flow Restriction Work?

The Benefits of Blood Flow Restriction

Many patients in our physical therapy clinic are unable to lift heavy weights – sometimes because of pain, immobilization, or because of surgery. Blood Flow Restriction (BFR) Training can be a great rehabilitation tool because it allows patients to reap the benefits of an intense heavy weight-lifting session while only requiring the patient to perform low-to moderate-intensity training. This reduces stress to tissues that may be healing from a recent injury or surgery. During BFR training, a patient or athlete performs high repetitions of a particular exercise while wearing a band or cuff around their upper arm or upper leg with use of light resistance. The following are physical changes that can occur secondary to Blood Flow Restriction Training:

• Improved muscular strength
• Increased muscular cross sectional area
• Prevention of muscular atrophy
• Development of newer and healthier blood vessels
• Decreased risk of cardiovascular disease
• Improved bone mineral density

BFR Causes Muscles to Work Harder

With elastic BFR training, BFR bands are placed near one’s upper arms and/or upper legs. It is important to note that elastic BFR bands do not cause complete occlusion of arterial blood (oxygen rich blood flowing from the heart to the limbs), so it can be safe for most patients. Elastic BFR bands partially restrict the venous blood (oxygen deficient blood flowing from the limbs back to the heart) return. This makes the muscles work even harder to pump the blood back to the heart!

BFR workouts involve periods of exercise and rest. During the periods of exercise, blood is rapidly circulated from our heart, to our arteries, to our limbs, to our veins and back to the heart. The elastic BFR bands can be equated to a dam. The muscles in the limb have to work even harder to pump the venous blood past the BFR bands back to the heart. At the local cellular level, this dam effect produces a disturbance of homeostasis – lower oxygen levels in the muscle cells, acidic muscle cells, and other changes that make the muscles fatigue quickly, just like they would with heavy weights. Then during the periods of rest, the muscle cells can recover, but it is important with elastic BFR that the bands be left on and inflated during these periods of rest to enhance the systemic benefits of BFR.

How the Brain Responds to Changing Oxygen Levels

Similar to heavy weight lifting, BFR Training allows your body to experience periods of rapid circulation of blood where oxygen is flowing throughout your entire circulatory system. The lack of oxygen in our limbs is noteworthy to our body, and our central nervous system sends the message to our brain that our limbs “aren’t getting enough oxygen.” It is very important to understand that the decreased oxygen levels that our body experiences is temporary, safe and essential for BFR to work. Once our brain gets the message that less oxygen is freely flowing, the brain sends out an “alert” to our endocrine system. The endocrine system involves glands that release certain hormones into the bloodstream. When using BFR, the anterior pituitary gland in the brain responds by releasing growth hormone, which helps with muscle cell reproduction, muscle cell regeneration, and lipolysis (fat breakdown).² This alert with BFR also stimulates release of insulin-like growth factor-1 (IGF-1), which is important for muscular hypertrophy, muscle and bone growth, and regulation of DNA synthesis.²

How Your Limbs Respond to Changing Oxygen Levels

Locally, our arms and our legs also sense the body’s temporary lack of normal oxygen levels. Because of this, two things happen—our fast twitch muscle fibers are trained and our muscles cells are regenerated.

1. The lack of oxygen to our limbs makes our muscles fatigue more quickly and allows for the training of our “anaerobic, fast twitch” muscles.³ Anaerobic, fast twitch muscles are needed to run faster and jump higher. These include muscles like our calves, quads, hamstrings, biceps, triceps and other muscles that may be key in your rehabilitation.
2. The lack of oxygen at the cellular level encourages protein synthesis.^1,2,5 Protein synthesis is key to muscle repair and muscle strength.

Making Rehabilitation Gains at a Faster Rate

Numerous studies have shown that similar physiological benefits can be found when comparing heavy, high intensity exercise to light to moderate intensity exercise with the use of BFR. Lifting heavy weight is great for muscle building and muscle hypertrophy, however is not always possible following a surgery as it can sometimes be painful or cause too much stress to injured tissue. BFR training makes our brain and our limbs think they are working harder than they actually are—all while lifting low to moderate weight and working at moderate intensity.³ And what’s even better is that BFR Training helps us achieve these physiological benefits at a faster rate compared to normal rehabilitation exercise.^4,5 Ultimately, BFR training supports our patients return to normal movement patterns and activities!

Blood flow restriction (BFR) services are available at select Athletico clinics performed by trained clinicians. If you are interested in learning more about BFR or Athletico’s relationship with B-Strong, a blood flow restriction (BFR) training company, click here to see a video on our website. If you are interested in scheduling an appointment and incorporating BFR into treatment, click the button below to request an appointment.

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The Athletico blog is an educational resource written by Athletico employees. Athletico bloggers are licensed professionals who abide by the code of ethics outlined by their respective professional associations. The content published in blog posts represents the opinion of the individual author based on their expertise and experience. The content provided in this blog is for informational purposes only, does not constitute medical advice and should not be relied on for making personal health decisions.

References:
1. Dankel, S. J., Jessee, M. B., Abe, T., Loenneke, J. P. (2016). The Effects of Blood Flow Restriction on Upper-Body Musculature Located Distal and Proximal to Applied Pressure. Journal of Sports Medicine, 46, 23-33.
2. Loenneke J.P., Wilson, G. J., Wilson, J. M., (2010). A Mechanistic Approach to Blood Flow Occlusion. International Journal of Sports Medicine, 31, 1-4.
3. Luebers, P. E. With, E. V., Oshel, J. Q., Butler, M. S. (2019). Effects of Practical Blood Flow Restriction Training on Adolescent Lower-Body Strength. The Journal of Strength and Conditioning Research, 33 (10), 2674-2683.
4. Hughes L;Paton B;Rosenblatt B;Gissane C;Patterson SD; “Blood Flow Restriction Training in Clinical Musculoskeletal Rehabilitation: a Systematic Review and Meta-Analysis.” British Journal of Sports Medicine, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/28259850/.
5. Takarada Y;Takazawa H;Sato Y;Takebayashi S;Tanaka Y;Ishii N; “Effects of Resistance Exercise Combined with Moderate Vascular Occlusion on Muscular Function in Humans.” Journal of Applied Physiology (Bethesda, Md. : 1985), U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/10846023/.