BFR Training to Optimize the Rehab Process

Blood flow restriction (BFR) training has huge implications for rehab.  From both an injury and a post-surgical perspective, BFR training certainly has the capability to optimize the rehab process by allowing us to tap into hypertrophy and strength very early on in the rehab process.

While BFR may be relatively new in the rehab world, it has been out since the 1960s!! It was developed in Japan and formally known as KAATSU training. Since the 90s, it has been studied considerably, mainly because of the enthusiasm around its benefits for hypertrophy training. It is indeed possible to achieve hypertrophy using BFR combined with low-load resistance training and this is supported by a growing volume of new research.

If BFR training is not something you are accustomed to using in your practice, here’s something to get you started and trigger some ideas on how you might be able to integrate it.

The physiology behind BFR

BFR training consists of applying an occlusion such that blood is able to enter the muscle via arterial circulation (flow in) but partially prevented from leaving the muscle via the restriction of venous circulation (flow out).  Occlusion is applied on the proximal aspect of an upper or lower extremity (but never all four limbs at the same time). It is important to understand that fully occluding both the veins and arteries, or applying the cuff in areas other than the proximal aspect can result in injury or damage to muscles and/or other structures (such as nerves, for example).

Blood flow restriction causes a buildup of metabolites, such as lactic acid, inorganic phosphate and hydrogen ions.  The metaboreceptors in the muscles detect changes in metabolic environment, which are communicated to the brain and result in an increase  in the recruitment of Type 2 motor units.  Essentially, BFR creates a high-intensity environment in the muscle.  The metabolic stress induced by BFR causes an increase in the muscle hypertrophy signal cascade, despite the fact that the individual is performing with loads representing 20-40% of their 1RM.  Simply put, the main advantage of BFR training is that you can increase muscle size at very low loads.

Equipment & how to use it

Wide or narrow cuff

Wider cuffs, around 10-15cm, require less pressure and may thus be less painful to achieve venous occlusion. However, some research has shown that a narrower cuff (5-9 cm) decreases the risk of occluding the arteries.  The circumference of the limb to occlude would also play a role in the matter, a wider girth would require more pressure to achieve an equal level of occlusion.

Cuff Pressure

There are multitudes of BFR pressure methods depending on the type of cuff you are using and the individual. The BFR should be high enough to occlude venous return but low enough not to harm the athlete. Indeed, high pressure could increase complications without any muscular advantages. The key for optimal pressure is that it must be high enough to occlude venous return but low enough to maintain of arterial flow. The gold standard is to use a Doppler ultrasound or plethysmography to determine the amount of blood flow to the limb. The cuff pressure is then determined to allow 50-80% of arterial flow (50% for the upper body and 80% for the lower body). A perceived pressure of 7/10 in intensity relative to your maximum tolerable pressure for the lower body and 5/10 for the upper body would result in venous occlusion while still allowing partial arterial blood flow.  It should be noted that larger limbs will also require higher pressure for occlusion.

There are many other different blood flow restriction cuff pressure prescription methods such as using a pressure relative to the patient’s systolic blood pressure, approximately 1.2- or 1.5-fold greater than the systolic blood pressure.

Clinical Application

In rehabilitation, restoring muscle size and strength is crucial.  BFR can be implemented during the rehabilitation process to limit muscle atrophy and increase strength in the early phases of rehab. For example, BFR can be utilized for post-surgical ACL rehabilitation. Post-ACL reconstruction immobilization can result in disuse atrophy of the vastus lateralis after just 5 days!  Two weeks of immobilization can result in as much as a 30% decrease in muscle strength.  This is a critical period for the muscle.  In the earlier phases, when loading capacity is limited, using BFR at low loads can prevent disuse atrophy of the quadriceps and hamstrings.

Additionally, you can use BFR for traditional rehab early rehab exercises such as the terminal knee extension (Video 1) exercise and the stability ball hamstring curl (Video 2) to create a hypertrophic environment at low loads.

As you progress during the rehab process, you will want to include more multi-joint exercises to prepare your athlete for return to play. Here again, BFR training is a great tool to get results similar to using high loads without the strain on the body.  The video below shows the BFR utilized during a back lunge.  Additionally, BFR can be used in combination with neuromuscular electrical stimulation (NMES) as a valuable tool for maximizing muscle activation when mechanical loading is limited such as in the early post-operative phase.

General Parameters

Training Intensity & Volume

What should the intensity be?  BFR recruits the larger, fast-twitch muscle fibers, which are activated by either heavy resistance or fatigue.  As such, optimal use of the BFR involves failure under low-intensity conditions.  Research has shown gains with as little as 20% of 1RM and suggests up to 40% of 1RM to maximally recruit fast-twitch muscle fibers.

The recommendation for total repetitions per exercise is between 50-80. The standard protocol currently is 30-15-15-15 repetitions with 30 seconds rest between sets.  The cuff should remain inflated during the rest period, however, the recommended total time under hypoxia is 6 to 10 minutes.  This means that if you are utilizing the BFR for two or more exercises, you will need to deflate the cuff between exercises for one to two minutes.

When integrating BFR early on in the rehab process for classic low-intensity exercises such as terminal knee extensions (or even quad sets), you can manipulate these parameters slightly.  Exercises like quad sets and terminal knee extensions would benefit from continued application of the BFR to mitigate hypertrophy and increase muscle activity through fast-twitch fibers to re-activate the quadriceps.

Other applications

CrossFit or high-level athletes who want to work on a weaker muscle groups without adding too much fatigue to their system due to their already busy training schedule. It could also be used as a recovery tool or prehab program for those athletes who are prone to injury.

Bodybuilders as a metabolic finisher after a traditional hypertrophy workout or as a way to isolate lagging muscle groups.

In-season athletes could also benefit from this training method when they have multiple games close together. BFR could be used as a training method between games and traditional strength training when they have a longer break.

Endurance athletes can also use BFR to increase VO_2max while walking or cycling. For example, low intensity cycling exercise has been shown to improve aerobic capacity.

Optimizing the rehab process

The implications of BFR training from a rehab perspective are quite interesting.  The use of BFR to create a high-intensity metabolic environment where and when load-capacity is decreased has many benefits for a timely return to play.  Even during periods of non-weight bearing, BFR has been shown to have an effect on disuse atrophy and muscle protein synthesis, resulting in less decreases in muscle strength.

BFR brings a whole new meaning to early mobilization.  As we continue to study its benefits, results are already sufficient to show that more emphasis should be put into consistently integrating it into the rehab process.

If you are interested in learning more about the science behind BFR training, Dr. Mario Novo is pretty much the person who explains it best.  He’s got a series of articles on Mountain Dog Diet.

Léa Thibault, B.Sc., CAT(C)
Certified Athletic Therapist

Léa joined Rehab-U in November 2019. She holds a Bachelor’s degree in Athletic Therapy from Concordia University and is currently pursuing her Master’s degree in Kinesiology at the Université de Montréal. A former member of the national speed skating development team and currently a coach at the Laval Regional Short Track Center, Léa understands the importance of strength and conditioning for rehabilitation and prevention. With four years of experience on the field and in the clinic, she has had a great role to play in the rehabilitation and return-to-play of several athletes. Léa also acts as a therapist for several international and national sports events in Quebec.