Blood Flow Restriction Training
Nov 19, 2019
What is it?
Blood flow restriction (BFR) training involves performing low intensity strength training while wearing a circumferential wrap (tourniquet, blood pressure cuff) to occlude venous blood flow, but not arterial blood flow, to working muscles (2); one study also used knee wraps applied to the thighs to achieve this pressure (5). This type of training is based on KAATSU training developed in Japan in the late 1960’s by Yoshiaki Sato (4). BFR training has been reported to increase muscle strength and size without having to work at the usual recommended intensity of 60-85% of 1 rep max (1RM) which may not be attainable for some populations. In fact, muscle strength and hypertrophy gains have been shown with training at intensities as low as 20% 1RM with BFR (2).
How does it work?
BFR training is thought to work via 3 primary mechanisms: (1) increased cellular swelling; (2) enhanced metabolic stress; (3) increased muscle fiber recruitment (5). Similar metabolic factors that stimulate muscle growth with high intensity resistance training have been reported with low intensity BFR training. Occluding venous blood flow results in muscle cell swelling activating chemical pathways responsible for building muscles (2). Cell swelling shifts the protein balance in favor of anabolism and stimulates hypertrophy (5). Creating a hypoxic environment for the muscles by restricting blood flow allows lactate to accumulate resulting in decreased muscular pH which upregulates Growth Hormone (GH). A build-up of lactate and drop in pH has also been shown to stimulate recruitment of more fast-twitch (FT) muscle fibers (2). Activation of these FT fibers is shown to be closely related to muscle protein synthesis (5). Interestingly, some research has even shown BFR training to have a cross-over effect, strengthening other muscles that are not directly involved in the training (1).
There are many variables that determine appropriate dosage for achieving muscle strength and hypertrophy results from BFR including cuff width and limb size. A general guideline based on current research is: moderate partial occlusion pressure of 130-180mmHg; occlusion duration continuous for the length of the session (not to be removed during rest periods); exercise intensity of 20-30% 1RM; dosage of 3-4 sets of 12+ reps (2). Similarly, other research has recommended working at 20% 1RM 2-3 days/week at 75 reps over 4 sets (30/15/15/15) with 30 second rest intervals (4). The previously mentioned study using knee wraps applied to the thighs based the pressure on participant feedback, that they felt pressure but no pain and would rate the pressure felt as a 7/10 (5).
It is important to consult a health care practitioner before beginning this type of training. If cuff pressures are too high, it is possible to cause nerve damage. Individuals with cardiovascular disease, hypertension, heart failure, or peripheral artery disease should consult their physician before beginning BFR training (2).
How physiotherapy can help
BFR training may be an effective addition to rehabilitation of various orthopaedic conditions such as osteoarthritis, tendinopathies, ACL reconstruction, hip and knee arthroscopies, tendon repairs and muscle strains; this is due to the fact that it allows for greater strength gains without placing a lot of stress on the heeling tissues. Your physiotherapist can discuss with you whether BFR training is appropriate for you and provide equipment and techniques to incorporate this training into your rehabilitation program (2).
(1) Bowman, E. N., Elshaar, R., Milligan, H., Jue, G., Mohr, K., Brown, P., … Limpisvasti, O. (2019). Proximal, Distal, and Contralateral Effects of Blood Flow Restriction Training on the Lower Extremities: A Randomized Controlled Trial. Sports Health: A Multidisciplinary Approach, 11(2), 149–156. doi: 10.1177/1941738118821929
(2) Madden, S. J. (2019). Current Evidence for the Use of Blood-Flow Restriction in Resistance Training. Journal of Australian Strength & Conditioning, 27(4), 63–67. Retrieved from https://search-ebscohost-com.login.ezproxy.library.ualberta.ca/login.aspx?direct=true&db=s3h&AN=138661817&site=eds-live&scope=site
(3) Blood Flow Restriction Training. (n.d.). Retrieved November 19, 2019, from https://physio-pedia.com/Blood_Flow_Restriction_Training.
(4) VANWYE, W. R., WEATHERHOLT, A. M., & MIKESKY, A. E. (2017). Blood Flow Restriction Training: Implementation into Clinical Practice. International Journal of Exercise Science, 10(5), 649–654. Retrieved from https://search-ebscohost-com.login.ezproxy.library.ualberta.ca/login.aspx?direct=true&db=s3h&AN=124925933&site=eds-live&scope=site
(5) Wilson, J. M., Lowery, R. P., Joy, J. M., Loenneke, J. P., & Naimo, M. A. (2013). Practical blood flow restriction training increases acute determinants of hypertrophy without increasing indices of muscle damage. Journal Of Strength And Conditioning Research, 27(11), 3068–3075. https://doi-org.login.ezproxy.library.ualberta.ca/10.1519/JSC.0b013e31828a1ffa
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