What is Blood Flow Restriction?
The first time I saw someone holding a three pound dumbbell with a cuff around their arm grunting about how badly it burned, I thought, “No way.” But once I tried it two separate times as part of a rehab program for my own knee and shoulder, I realized that BFR was no joke.
BFR works by partially restricting arterial inflow to the muscle and fully restricting venous outflow from working muscles. This basically means that only some oxygenated blood flows into the working muscles and no deoxygenated blood flows out of the working muscles. BFR uses low loads (20-30% of 1 RM), high reps (15-30) and short rest intervals (30 seconds). In doing this, muscular size, strength, and endurance can improve in similar proportions to that achieved by heavy weightlifting. Studies show that, “short duration, low intensity BFR training of around 4-6 weeks has been shown to cause a 10-20% increase in muscle strength. These increases were similar to gains obtained as a result of high-intensity exercise without BFR” (Physiopedia 2020).
For those with whom heavy lifting may be contraindicated, such as after surgery or injury, BFRT becomes a very useful tool to use as part of the rehab process to improve strength and muscular endurance. Many bodybuilders also utilize BFR to increase muscle size.
So how does BFR work? The cuff is placed above the muscle you want to strengthen. For example, if you were trying to strengthen the knee post ACL surgery, the cuff would be placed at the very top of the thigh. Because blood flow is restricted to the muscles, oxygen supply to the muscles is also limited. Muscles below the cuff then have to work harder to make a muscular contraction because of reduced oxygen delivery. The increased fatigue of the muscles under BFRT mimics the fatigue experienced by muscles during heavy lifting, which is why we see similar results in hypertrophy with both methods.
History of BFRT
BFR began in Japan in the 1960s and was created by Dr. Sato, a guy just looking to make his muscles bigger. Dr. Sato experimented using homemade tourniquets and called the practice Kaatsu Training, which means “training with added pressure.”
Dr. Sato spent years experimenting with blood flow restriction and even ended up in the hospital a few times due to his homemade tourniquets. (Note: BFR should only be done by a professional; please don’t try tying bands around your arms and legs in hopes of increasing muscle size.) Through his many years of experimentation and extensive research, it became clear that blood flow restriction could be effective in increasing muscle size, strength and endurance. While still used by many bodybuilders, BFRT is now gaining traction in the clinical setting as a means to rehab from injury or surgery.
How is BFR beneficial following an ACL injury or surgery?
A 2020 review delved into BFR specific to ACL rehab and states, “The goal of blood flow restriction therapy is to prevent muscle atrophy, regain endurance, and restore range of motion in patients recovering from ACL reconstructions” (Charles et. al 2020). At Made 2 Move, we combine BFR with exercises like the leg extension, squat, and step up, as well as sport specific exercises to maximize your recovery post operatively and minimize muscle loss. Our athletes tend to enjoy BFR because it challenges them physically and prepares them mentally to get back on the field or court.
Another review on BFR found improvements in quadriceps strength and knee pain in patients who did BFR vs. traditional rehab after ACL reconstruction. Minimizing pain and improving quadriceps strength are two of the primary outcome measures in our ACL athletes that determine their return to play!
Many athletes worry about the integrity of their newly constructed ACL post surgery. We want the new ACL to stay taut like a rope, so it can withstand the forces going through the knee but also have the ability to move through functional ranges of motion. In regards to the ACL graft following BFR training, “ACL graft laxity was measured pre-operatively and at 10 up to 16 weeks postoperatively,” with no major differences in laxity between the BFR group and traditional exercise group (Koc et. al 2022).
The 2022 review also emphasized that, “A major challenge in the rehabilitation after an ACL reconstruction is optimizing muscle strength while minimizing mechanical stress to the knee joint”(Koc et. al 2022). At the Made 2 Move ACL Performance Lab, our athletes are eager to get back to their sport. Our #1 priority is to protect your new ACL and get you out of pain. BFR allows us to improve your strength, coordination, and pain while not compromising the healing of your new graft.
What else can BFR be used for?
At Made 2 Move, we are big fans of lifting heavy: we know that lifting heavy weights makes you stronger! But what happens when someone is unable to lift heavy weights due to injury, surgery, illness, or other restrictions? How can we still elicit the same muscular adaptation? Enter BFR.
BFR can be used after an ACL surgery, but can also be used for minor injuries as well. Let’s say you tweaked your shoulder doing snatches at Crossfit. You have pain while doing any overhead movement now, so BFR could be a useful tool to maintain or increase strength and muscular endurance through that area so that your shoulder is stronger when it becomes time to return to those overhead movements.
Ready to get your BFR on?
Maintaining intensity of training and overall strength following injury or surgery is one of the biggest challenges for athletes and gymgoers. BFR is one of the tools we utilize at Made 2 Move to build strength so that you can get back on the field or in the gym. Are you coming back from injury and feel ready to train, just not quite at 100% intensity? Are you trying to prevent regression at the gym after you got a minor tweak in your shoulder or knee? Coming back from ACL surgery and trying to optimize your rehab? Reach out to firstname.lastname@example.org today to set up an initial consultation!