BFRT is one of the newest tool to hit both the rehabilitation and performance world with a surge of research coming out supporting the use of this modality for strength and hypertrophy gains.
If you are a rehabilitation clinician, sports medicine doctor or athletic trainer you have probably heard about BFRT by now. If you haven’t this blog will give you the nuggets of it
What is BFRT ?
BFRT is a form of safe low intensity resistance exercise (LIRE) that when applied has demonstrated enhanced muscle growth, muscle strength, oxygen delivery and utilization (VO2Max), collagen dependent tissue repair, and increased bone healing following a fracture.
It utilizes the application of an inflatable pneumatic cuff or wraps around a limb to limit the amount of blood flow available to the exercising muscle. The goal is to fully occlude venous blood flow out of the exercising limb and restrict a certain percentage of blood flow into the exercising limb.
So, what is the common characteristics and deficits that we see with our patients in the clinic besides a presentation of pain?
We know that addressing Strength in our rehab is pertinent as it has :
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- Helps reduce future injury
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- Rehab quicker from current injury
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- Engage in activities without compensation
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- Allows for return to ADLs and occupation demands
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- Improve confidence and self esteem
Hence the maintenance of skeletal muscle becomes increasingly important especially with advancing age, as low levels of muscle mass are strongly correlated with a loss of independence, mobility and an increased risk of disability and functional impairment.
The science of Hypertrophy and BFRT
The growth of muscle, or muscular hypertrophy, is the result of metabolic stress (accumulation of lactate and hydrogen ions from the breakdown of ATP) and/or mechanical stress (time under tension).
When the muscle undergoes either one of these situations, it leads to activation of pathways critical to muscle growth, namely the mTOR pathway. Growth hormone (GH) and IGF-1 are key upstream triggers for this pathway. Therefore, anything we can do to increase the production and release of these hormones will aid in muscular hypertrophy. Proper sleep and recovery, nutrition, and exercise all impact GH and IGF-1.
Traditional high intensity strength training induces both of these adaptations, but at the same time increases transient damage to the muscle and soft tissues.
An important side note is that exercise and training indirectly impact the pathway associated with vascular endothelial growth factor (VEGF) which is responsible for repair and growth of blood vessels (angiogenesis). This is therefore helpful in clinical populations such as hypertension (HTN), where an increase in blood vessels would reduce overall pressure within the cardiovascular system, reducing blood pressure (BP).
In order to experience gains in strength and mass, Research has shown that on traditional loading requirements for hypertrophy loads as heavier than 65% of an individual’s one rep max (1rm) must be used to create hypertrophy gains. However most patients within the clinical settings are not able to exercise at high intensities due to post-operative protocols (ACLR, TKR etc ), pain, fear avoidance behaviour…the list goes on!
Research on blood flow restriction training shows that loads as low as 20-30% of 1rm can create the same hypertrophy stimulus!
Research looking at strength gains has shown significant increases in strength during BFR training. Compared to typical high intensity training, these strength gains are lesser, but can still have significant impact.