Blood flow restriction (BFR) training is, without a doubt, the most exciting innovation in exercise training I’ve encountered in my 50 years of exercise. To help us walk through how it’s done, and its many health benefits, is Dr. Jim Stray-Gundersen — an expert in BFR who has trained many elite and professional athletes.
BFR training was developed by Dr. Yoshiaki Sato in Japan in the mid-60s, where it’s known as KAATSU training. Stray-Gundersen met Sato and worked with his organization, KAATSU Global, for a while. Stray-Gundersen explains the history and origins of this breakthrough system:
“Sato had an epiphany in 1966. He was busy attending a funeral service. He ended up having to sit in a certain position where we would say our legs fell asleep. When he tried to get up, his legs didn’t work very well. This reminded him of when he would exhaust himself with heavy weightlifting. That just kind of stuck in his mind …
In 1973, he had a ski accident. He ended up in a full-length leg cast. As most physicians know, these full-length leg casts produce lots of atrophy. He had been, in a way, just playing around with this idea of BFR, but this was an occasion where he could try this out for himself.
He took a judo belt and wrapped it several times around the top of his thigh, above the cast. And then he did isometric exercises in the cast. In those days, the cast were routinely changed at six weeks, because there typically had been so much atrophy that the cast was now loose and really wouldn’t hold a fracture in the proper location.
When he reported to the physicians to change the cast, it turned out he really didn’t have much atrophy at all. His ankle fracture and his knee injury were now not tender. Instead of getting another cast put on for another six weeks, he basically just walked out of the clinic. That was the point for him to say, ‘Hey there’s really something here.’”
The Early Days of BFR
Over the next 30 years, Sato experimented on himself and his fellow bodybuilders, trying to understand the ins and outs of what they were calling occlusion training at the time. One thing he discovered was that he needed to use a relatively narrow elastic band.
He also realized he could control the pressure using a pneumatic bladder. Sato published his first paper in the English literature in 1998. Another paper was published in 2000, in which his team conclusively demonstrated BFR effectively increased muscle strength and hypertrophy. Since then, many more articles have been published on BFR by Sato1 and others.
“In my particular case, I’ve had a career in human performance and elite performance,” Stray-Gundersen says. “I’ve worked with Winter Olympians from cross-country skiers, alpine skiers, speed skaters and hockey players. In the Sumer Olympics, runners, swimmers, cyclists, triathletes, manly focused on endurance sports, but also soccer to a large extent.
My day job was a professor at the med school at the University of Texas Southwestern in Dallas. Through all these years, I always had my eyes out for things that could improve athletes’ performance, as well as be very useful for the population in general.
In 2011, I happened to run into a colleague at the American College of Sports Medicine Annual Meeting, who told me about KAATSU … My colleague told me how great this was and that you could get improvements in strength in as little as two weeks. I was quite skeptical at first … To make significant gains in strength and muscle size you need about six weeks.
The short story is checked it out and ended up contacting KAATSU Global and Steve Munatones. From there, [I got to] spend some time with Dr. Sato learning the ins and outs of KAATSU … It’s actually quite fantastic. It’s really a big paradigm shift in how we think about training and how to think about antiaging medicine, or using exercise as a medicine for health and fitness.”
Preventing and Treating Sarcopenia With BFR
It’s important to realize that without resistance training, your muscles will atrophy and lose mass. Age-related loss of muscle mass is known as sarcopenia, and if you don’t do anything to stop it you can expect to lose about 15% of your muscle mass between your 30s and your 80s.2
An estimated 10% to 25% of seniors under the age of 70 have it and up to half of those over the age of 80 are impaired with it.3 One of my biggest regrets in life is not knowing about BFR before my parents passed away.
They both had severe sarcopenia. I really believe they could have survived longer had I been able to teach them this technique earlier in their life. Sarcopenia is not just cosmetic, and it’s not just about frailty. Your muscle tissue is a metabolic organ, an endocrine organ.
Your muscle tissue makes cytokines and anti-inflammatory myokines, and is a sink for glucose. That’s the primary reason I’m so interested in BFR. It has the ability to prevent and widely treat sarcopenia like no other type of training.
BFR Training Is Excellent for the Elderly
There are several reasons for why BFR is so superior to conventional types of resistance training. Importantly, it allows you to use very light weights, which makes it suitable for the elderly and those who are already frail or recovering from an injury. And, since you’re using very light weights, you don’t damage the muscle and therefore don’t need to recover as long. As explained by Stray-Gundersen:
“Succinctly, what KAATSU does … is it allows you to get the same benefits you get from heavy standard lifting with very light weights — 20% to 30% of one rep max…
What we’re doing is we’re limiting the venous outflow out of an extremity, creating a situation in the working muscle where it’s not getting enough oxygen to sustain or to rebuild the energy stores that are used up in the course of that work. So, you set up this metabolic crisis where you’re not making enough ATP to replace the ATP that you’re using.
The consequence of that is you get a disturbance of homeostasis, which is just like the disturbance of homeostasis you get with very heavy lifting. The difference is that we’re doing it by modulating and impeding the blood flow as opposed to doing very hard work, which actually does damage to the tissue at the same time.
One of the reasons why you get these effects much sooner than typical is because we have altered the time scale by not doing the damage. Therefore, we’re getting the benefits of this exercise in very short order. Really, we’ve tapped into starting to understand what the real adaptation to exercise is.
It’s creating that stress or that disturbance of homeostasis that the body then reacts to in a systemic way … At the same time, it has to repair the damage that was done during the course of the exercise …
What’s really nice about [BFR], which I would generically characterize as an elastic, pneumatic, relatively narrow BFR[-band] training, is that we provide an anabolic stimulus very early on through this systemic effect.
One of the things that other papers have shown is it’s not just the muscle that’s getting better. It’s the bone. It’s the blood vessels. There’s even a study showing that the neural transmission from a motor nerve to a motor fiber is improved by BFR training.
We know that regular exercise helps us maintain as much function as we can. But as we age, we become unable to do those same kinds of workouts that it took to recreate this stuff in the first place. Now, with BFR we have the ability to do this with very light, easy exercises that anybody can do, and therefore, get the benefits of this anti-aging medicine.”
Elderly Need BFR Even if They’re Fit
While most elderly cannot engage in high-intensity exercise or heavy weight lifting, even extraordinarily fit individuals in their 60s, 70s and 80s who can do conventional training will be limited by their physiology in terms of the benefits they can achieve. The reason for this is because your microcirculation tends to decrease with age.
Your capillary growth is diminished, and capillary blood flow is essential to supply blood to your stem cells, specifically the fast twitch Type II muscle fiber stem cells. If they don’t have enough blood flow — even though they’re getting the signal from the conventional strength training — they’re not going to grow. You’re not going to get muscle hypertrophy and strength.
BFR, because of the local hypoxia that is created, stimulates hypoxia-inducible factor-1 alpha (HIF1A), and secondarily, vascular endothelial growth factor (VEGF), which acts as “fertilizer” for your blood vessels. VEGF allows your stem cells to function the way they were designed to when they were younger.
This is part and parcel of what makes BFR such a phenomenal exercise. What’s more, the hypoxia also triggers vascular endothelial growth factor, which enhances the capillarization of the muscle and likely the veins in the arteries as well.
“What’s really exciting about that is that now all of a sudden, we have something that can repair and build endothelium,” Stray-Gundersen says. “And the endothelium is the first order of business when we’re talking about the ravages of atherosclerosis.
One of the big applications in Japan is with cardiac rehabilitation and stroke patients. They do BFR training with these people, because they can. Even if they have some hemiparetic problem or difficulty walking, they can always do some sort of exercise that stimulates the fibers that are still intact.
This whole thing is a way to recruit as many motor units as possible in a body or a human. That, in turn, is a very powerful stimulus for reversing sarcopenia or building muscle and better blood vessels. All of these things are related.”
Essentially, BFR has a systemic or crossover training effect. While you’re only restricting blood flow to your extremities, once you release the bands, the metabolic variables created by the hypoxia flow into your blood — lactate and VEGF being two of them — thereby spreading this “metabolic magic” throughout your entire system.
Systemic Benefits of BFR
For this reason, BFR can be a powerful way to not only treat strokes but also preventing Alzheimer’s and heart disease. As noted by Stray-Gundersen, BFR can be likened to “Drano for the arteries,” and you’re only as young as your arteries.
What’s more, lactate, far from being just a waste product, is also viewed as a pseudohormone with powerful benefits. For example, lactate can cross your blood-brain barrier through a monocarboxylate transporter and stimulate brain-derived neurotrophic factor (BDNF). Stray-Gundersen explains:
“There’s a whole series of things that are produced when you disturb the homeostasis in a working fiber. One of them is lactate. We tend to think of these things as local mechanisms, whether it’s lactate or the hypoxia or a drop in pH. These things stimulate local protein synthesis.
We’re already doing stuff to build more and better blood vessels. But in addition, these factors can go to other cells in the area and help them. But the big deal is that we recognize this disturbance of homeostasis in our brains. Our brains end up saying, ‘Wow. Our muscles are feeling fatigued or they’re running out of gas’ …
We use that same sensory system to see how it’s going with BFR training. The ultimate message is that our muscles are in trouble. They’re not getting enough oxygen. They’re not regenerating the amount of ATP that they need to do this.
This is happening now in all the fibers — the Type I fibers at the beginning, but they drop out, and then they recruit the Type II, and let’s say the Type IIx, and stimulate the stem cells to differentiate into satellite cells and build new muscle fibers.
But now this message has gotten into the brain and the brain reacts to it by putting out a neurohumoral systemic response. This has been well characterized by an increase in circulating growth hormone in the 15 to 30 minutes after an effective BFR session.”
Growth Hormone Amplifies Protein Synthesis
Growth hormone stimulates insulin growth factor 1 (IGF-1) in your liver, which is an anabolic hormone. Being lipolytic, the growth hormone also goes to fat cells where it breaks down fat to produce substrates. It also plays a role in protein synthesis, along with lactate.
The take-home message is you end up getting adaptation everywhere, not just in the muscles used in the exercise. Stray-Gundersen explains:
“A way to think of this is that there’s a systemic process. For example, let’s say we’re doing bench presses. We’re using our triceps, for example, that may be distal to the band. But we’re also using our pectoralis major muscles.
Their blood flow is normal because the bands don’t get in the way of it. But they also get the benefit … Both muscles, proximal and distal to the bands, end up benefiting …
One of the things that happens — one of these local reactions — is self-surface receptors for growth hormone and for insulin and for a variety of anabolic hormones are upregulated, so there’s an increase in receptor density on the surface of cells used in the course of this exercise, for example the pecs and the triceps.
Growth hormone comes along and binds into these receptors, and that stimulates the mTOR pathway to upregulate protein synthesis. That’s where you get this amplification effect. It’s not that the growth hormone is stimulating mTOR.
It’s just that the hypoxia and the acidosis and the lactate acidosis in the cells have stimulated not only protein synthesis locally, but also the cell membrane receptors so that there’s a greater receptor density, and whatever growth hormone comes along ends up getting bound, amplifying the effect.”
Proper Occlusion Technique Is Imperative
To avoid injury, it’s important to use the appropriate type of occlusion bands, and to use the bands correctly. At present, there are essentially two different camps — the KAATSU camp, which uses very narrow elastic bands to control the pressure, and a more physical-therapy based camp that uses wider surgical occlusion bands.
The width of the cuffs and the ratio of occlusion are two important factors, as the only way to really hurt yourself with BFR is to occlude arterial flow. The risk of blocking arterial blood flow is high if you’re using wide and/or rigid bands. You want to slightly occlude venous flow only, not the arterial flow.
“All serious complications with BFR training happen if you happen to occlude the arterial inflow into an extremity,” Stray-Gundersen says. “The wider the cuff or the band, the easier it is to do that. If the cuff is rigid, as opposed to elastic, the easier it is to do that. Those are the two main factors.
These groups who have tried to use surgical tourniquets or blood pressure cuffs to do this, they first read Sato’s paper and were very excited but couldn’t get a hold of the KAATSU equipment at the time. As a result of that, they just picked up something they thought would do the same thing. Unfortunately, they didn’t quite understand what Sato was up to …
There’s a very narrow band of pressure or flow that is safe and effective. When you’re using something that is relatively narrow and elastic, then you have a much bigger window in which you can get enough blood flow restriction to be effective and still be safe throughout the time period you’re doing [the exercise] …
One of the really important things [is] what we call the muscle pump. Anytime you do any exercise, the working muscles contract; they get stiffer and a bigger … and that forces the blood out through the venous channels past through the venous blockade.
So, you’ve changed the venous flow from one in which you can think of as a lazy river where the venous flow was continually going back towards the heart, to one in which there are intermittent obstructions or occlusions of that venous flow with periodic pulsatile, high flow states. This ends up equaling the arterial inflow.
Usually, when you get into this kind of sweet spot of the right amount of BFR, you have decreased arterial inflow a little bit. But really, the big thing is you’ve changed the character or the venous outflow. You really can’t do that as well with a rigid system as you can with an elastic system, because when you have the muscles pumping this big amount of blood past the venous obstruction, if there’s a rigid outer casing, there’s just nowhere to go.
The muscles are getting thicker. It takes a tremendous amount of pressure to push any blood past this venous obstruction. If you have an elastic situation, now that elasticity can accommodate the increase in cross-sectional area and this increasing amount of venous flow.
While the rigid, wide systems can be made to work, there’s a very narrow window where they’re both safe and effective. On the other hand, with the elastic, relatively narrow ones, there’s a much larger window to get the pressures right.”
How to Find the Sweet Spot
So, how do you find that sweet spot, where venous flow is restricted, while arterial inflow is not? One way to make sure your arterial inflow is preserved is to feel for your pulse distal to the band. If the band is on your arm, you’d check the pulse in your wrist. If you have trouble feeling your pulse, you can check your blood flow by pushing hard on your hypothenar eminence and then release it.
The hypothenar eminence is the meaty portion on the palm-side of your hand at the base of your thumb. If the skin goes from white to reddish or pinkish in a couple of seconds, you know your arteries are open. If it takes several seconds for the skin tone to come back, your band is likely too tight.
General Training Guidance
The traditional recommendation is to do three sets of repetitions with 30 reps in the first set, 25 in the second and 20 reps in the third set. The main thing you’re trying to do is create fatigue in the working muscle. Three or four sets of any given exercise will do that.
“We want that first set to last somewhere around 30 to 45 seconds,” Stray-Gundersen says. “Then we want what we call 30 to 45 seconds of pseudo-rest. The muscle pump is pushing blood past the venous obstruction when you’re exercising. That increases the flow through the system.
When you’re resting or pseudo-resting, now you don’t have that muscle pump to help you with the flow, so the actual environment in the working muscle fibers deteriorates even more.
That’s why we generally use three or four sets with a specific amount of recovery in between, where the person thinks they’re recovering or resting, but really, the situation, the metabolic situation is getting worse in the fiber. It’s all about creating this disturbance of homeostasis and this fatigue feeling.
And so, we have a number of variables to play with. We have the pressure in the bands. We have the kind of exercises that we’re doing. We have the weight load, which generally we’d want to keep very low. And we have the number of reps in a particular set, and then the number of sets for a given exercise … Generally, that takes, for arms and legs, somewhere around 30 minutes.”
As for placement, on your arms, you want to place the bands up high on the arm, on the top of the bicep at the base of the deltoid. On your legs, you’ll place the bands as high as possible, close to your crotch.
How Often Can You Do BFR?
Again, because you’re not damaging your muscle with heavy weights, your recovery time is quite short. If I stick to the 20% to 30% one-rep max weight, I can easily do it every day. According to Stray-Gundersen a younger athlete may be able to do it twice a day. Some injured athletes end up doing three workouts per day.
“Generally, the 20 to 40 crowd can tolerate five [BFR] workouts a week. Generally, the 40 to 60 can tolerate three workouts a week. The greater than 60 ends up being twice a week,” Stray-Gundersen says.
Markers of a Good Session
The disturbance of homeostasis caused by the occlusion will trigger serious sweating, which can be used as a gauge that everything is working correctly. As mentioned growth hormone is triggered, which activates your sympathetic nervous system.
Sympathetic nervous system activation causes you to sweat and breathe harder. It also causes your blood pressure and heart rate to rise. All of these signs are markers of a good fatigue signal in the muscle.
“We look for increased sweating and inappropriately heavy breathing, that sort of thing,” Stray-Gundersen says. “When you have those things, you know you have had a good session.”
Another workout strategy recommended in KAATSU is KAATSU walking, where you simply walk for 20 to 40 minutes wearing the occlusion bands on your legs. For example, you can wear all four bands while rowing, cross-country skiing, cycling or jogging. After 15 to 30 minutes, most will be too fatigued to continue.
“In the case of running, it decreases the amount of pounding you get in return for getting in shape,” Stray-Gundersen says. “We also use this in the water.”
Hypertensive Response and Other Risks
If you have high blood pressure, conventional exercise could potentially trigger a stroke. Some of the literature suggests BFR may have a similar effect. However, Stray-Gundersen emphasizes that this risk is an artifact of using the wrong types of bands, not BFR in general. He explains:
“Deep vein thrombosis (DVT) or blood clots in the veins in the extremity can be deadly … But Dr. Rudolf Virchow back in the 1800s, [found] there were three conditions that were necessary [for DVT to occur]. One was venous stasis. If you don’t have arterial occlusion, you don’t get venous stasis.
If you’re doing the exercises where the muscle pump is pushing the venous blood past and the arterial is backfilling into this space, then you never get stasis. One of the things about being safe is to never occlude the arteries. That way, you never get venous stasis.
That way, you don’t get deep venous thrombosis. The other aspect or another one-third of the Virchow’s triad is endothelial damage … With normal BFR training, you don’t injure those vessels at all. You also don’t get this endothelial damage that can start a clotting cascade …
The same cannot be said for these wide, rigid systems … [similar to] what are used in the operating room and basically have a pretty high incidence of DVTs associated with them. The other thing was hypertension … It is a real and important consideration when you’re using the wide, rigid systems.
Also, the wide, rigid systems, when the muscles contract, as I said before, there’s nowhere to go. That induces ischemia and potentially damage to the exercising muscle. This causes a reflex exercise pressure response that can manifest as increasing hypertension.
One of my sons who’s doing a Ph.D. at University of Texas at Austin just did a thesis on the difference in hypertensive response to walking with narrow, elastic bands versus wide, rigid tourniquet system. He found that the wide, rigid cuffs ended up causing a very robust hypertensive response …
When he used the narrow, elastic bands, [the hypertensive response] ended up being no different. In fact, slightly less than just walking on the treadmill by itself without any bands on it. I think it relates to this idea of a relatively narrow elastic setup that doesn’t elicit this kind hypertensive risk that the wider systems and rigid systems do.”
BFR Training Is Ideal for Most
I really think BFR is one of the most important components of an effective anti-aging strategy. Stray-Gundersen agrees, noting he’s seen dramatic improvements in fitness and function in people of all ages.
“I think the big contribution, when you get right down to it, is that this provides exercises that pretty much anybody can do,” he says. Frail individuals can even get significant improvement simply by using BFR bands while doing activities of daily living, such as rising and sitting down in a chair, or reaching for a high shelf using no weights at all.
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