Blood Flow Restriction in 500 Words

Blood Flow Restriction (BFR) Training has been one of the most important recent additions to the worlds of orthopedics and sports rehab.

How It Works

By partially restricting arterial (“fresh”) blood flow to a working muscle, we can restrict the amount of oxygen available to that muscle. Exercise in an anaerobic environment (“lacking oxygen”) forces the muscle to produce higher amounts of lactic acid. We can “trick” the muscle into thinking it is working hard, giving you that deep high-intensity workout burn, while only doing very easy exercise. That build-up of lactic acid causes not only causes increased muscle fiber recruitment, but also causes the body to increase production of Growth Hormone (GH), and subsequently Insulin-Like Growth Factor 1 (IGF-1). These 2 hormones are extremely beneficial for rehab. Growth Hormone increases collagen synthesis throughout the body, which is a clear advantage when rehabbing an injured tendon or ligament. With larger, stronger tendons, it also doesn’t hurt to have larger, stronger muscles – IGF-1 has been known as a major driver of muscular hypertrophy.

They physiologic gains don’t stop there! Myostatin is a gene in the body that limits muscle growth. (Myo = Muscle, Statin = Stays the same). By downregulating the myostatin gene, BFRT can help the body grow more muscle, which is very important during rehab from some injuries and surgeries.

Why it is Relevant

There are 3 different types of muscle fibers in skeletal muscle:

  • Type I, which are aerobic, slow twitch and low-force producing. Think “endurance” fibers that are small, but long-lasting.
  • Type II X, which are anaerobic, fast-twitch and high-force producing. Think “explosive fibers” that are large, strong, and get tired quickly.
  • Type II A, which are somewhere in between. They are fast-twitch, but medium-force producing and partially aerobic (though exhaust faster than Type I fibers).

Type I fibers are utilized for most of the low intensity things you do during daily life. You don’t need to access Type II fibers until you are doing high intensity sprints or heavy lifting. Using BFR allows us to access the Type II fibers during light activities, which directly leads to increased muscle strength and hypertrophy despite not being able to load the muscle adequately (due to pain, post-operative status, etc.). This will expedite the rehab from orthopedic surgeries, and will also help maintain muscle mass while dealing with various overuse injuries.

A study performed by Park et al. in 2010 showed that walking with blood flow restriction applied to the legs led to an 11% improvement in in VO2 Max over just 6 weeks. This experiment was done on Division II Basketball players, not un-trained individuals. This has major implications for endurance athletes rehabbing an over-use injury – keeping a high level of cardiovascular function during times of limited capacity is crucial for returning to peak performance.

Blood Flow Restriction cannot (and should not) replace heavy loading during rehab, but can act as an intermediary supplement with similar effects until heavy loading can be safely performed.

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