Blood Flow Restriction Training
Can reducing blood flow build bigger muscles?
Everybody loves a shortcut. Get the same results but with less time and effort. When it comes to the body, you’re usually given a choice. You can take it easy, but then you’ve got to exercise for a long time. Or you can get it done fast, but then you’ve got to ramp up the intensity.
Blood flow restriction (BFR) training promises better results in less time AND with less effort. Here’s how it works.
You use a cuff around your arm or leg to restrict the flow of blood. Imagine the cuff from a blood pressure monitor. As it’s inflated, it begins to restrict the blood that can circulate in that limb.
When you dramatically reduce blood flow to a limb like your arm, it deprives the muscle tissue of oxygen. That’s known as hypoxia. Blood begins to pool within the capillaries of the limbs that have cuffs on them, and skin begins to redden. When you start to exercise that limb, it further disturbs blood flow and increases blood pooling.
Now here’s the crazy part. With the cuff restricting blood flow, you exercise. You do a physical therapy move, resistance or aerobic exercise. But you don’t use your regular weight.
In traditional weight training, you need to move weight that’s at least 60-70% of your one rep maximum for muscle growth and strength gains. The beauty of BFR is a person going through rehab can still see improvements with loads as light as 20-40% of your one rep maximum. That’s one-half to one-third your normal weight.
After you’ve finished a couple sets, you move the cuff to the opposite arm or leg and repeat.
HOW IT WORKS (THEORETICALLY)
There is a lot of speculation on how BFR works, but the simplest explanation appears to be fatigue. When you restrict blood flow, muscle fibers that need oxygen won’t work as well. That means type II muscles (which require very little oxygen) are stressed more because they’re working extra hard. Muscle grows by stressing it, so all that extra stress increases muscle size and strength.
Blood flow restriction training is also known as “Kaatsu training” and occlusion training. This isn’t a new technique. Dr. Yoshiaki Sato developed it in the 1960s and 1970s. Fortunately, there’s been a significant amount of research into BFR over the last ten years, giving us a much better idea of what works and why.
Let’s say you’re recovering from an accident. While you’re healing, your doctor told you not to lift any heavy weights. With BFR training, you only need to use a fraction of your normal weight. It’s important to note that BFR training does not provide BETTER results than resistance training with heavy weights. It IMPROVES the results you get from moving lighter weights; when you’re physically restricted from moving anything heavier.
Wider cuffs seem to be more efficient than narrow cuffs at reducing blood flow, but wide cuffs are also more likely to interrupt a full range of movement. You don’t want too large a cuff interfering with your exercises.
Put the cuff on too tight, and your limb will go numb. Leave it on for long periods (like an hour or two), and you’ll start experiencing cell damage. The key is applying the right amount of pressure, only as long as it’s needed.
There are dozens of companies selling straps and bands you can use to restrict blood flow. DON’T USE THEM. Clinical trials use cuffs that dynamically adjust to your arms. You can’t be as precise with a strap you tighten up like a tourniquet.
The amount of pressure that should be applied ranges widely. Many studies show benefits using the same amount of absolute pressure for every individual. However, when you can’t make adjustments for individual preferences, the subjects report more discomfort.
To maximize gains and minimize pains, use a cuff that can adjust. Start by inflating it to the point where blood flow ceases to a limb; that’s 100%. Then reduce the pressure to between 40 and 80% of that maximum. Start at the higher end of 80% but reduce the pressure if you feel numbness, tingling or pain in your extremities.
The documented risks for BFR are low, but that doesn’t mean it’s completely safe. In a 2018 study in the Journal of Orthdopaedic and Sports Physiology, researchers found that patients who had orthopedic surgery were at higher risk of developing blood clots if they used BFR during recovery.
Prior medical conditions like an active infection, cardiac disease, clotting disorders, deep vein thrombosis, high blood pressure or pregnancy can increase the risk of harm from BFR. You should NOT try BFR training without clearance from your doctor. You shouldn’t attempt BFR without the aid of a certified trainer or physical therapist that’s been taught how to implement it safely.
The ideal groups that could benefit most from BFR training and people going through rehabilitation after an injury that prevents you from lifting heavier weights. OR for the extreme bodybuilder, that’s already maxed out the amount of weight they can lift safely. The scientific literature doesn’t show much benefit for people who are in-between those two extremes.
Blood Flow Restriction Exercise: Considerations of Methodology, Application, and Safety
Stephen D. Patterson, Luke Hughes, Stuart Warmington, Jamie Burr, Brendan R. Scott, Johnny Owens, Takashi Abe, Jakob L. Nielsen, Cleiton Augusto Libardi, Gilberto Laurentino, Gabriel Rodrigues Neto, Christopher Brandner, Juan Martin-Hernandez, and Jeremy Loenneke
frontiers in Physiology, 2019 October 22; 10: 1332.
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