What Is Blood Flow Restriction Training?


If you’ve ever seen someone in the gym with bands around their upper arms or legs and thought they looked… well, a little crazy, here’s an interesting fact: They were probably practicing blood flow restriction training (BFR), also known as occlusion training. While it might look weird to the uninitiated, it’s actually a highly effective method of getting stronger and growing your muscle mass while using weights that are way lighter than what you’d normally need to use to reap the same effects.

But that doesn’t mean everyone should be doing it. Here’s what you need to know about BFR, including how to tell if it’s right for you.

How does blood flow restriction training work?

Blood flow restriction means using a specialized tourniquet system (not unlike what a nurse or similar would wrap around your arm before drawing blood) to decrease blood flow to your limbs, explains Hannah Dove, D.P.T., A.T.C., C.S.C.S., a doctor of physical therapy at Providence Saint John’s Health Center’s Performance Therapy in Santa Monica, CA. The tourniquet is typically wrapped around the arms just under the shoulder or around the legs just below the hip.

If you do BFR in a physical therapists office, they will often have a version that looks similar to a blood pressure cuff, which allows the PT to control the level of blood flow restriction.

Why do that? Well, with traditional strength training, you need a heavy load (at least 60 to 70 percent of your one rep max) in order to make your muscles stronger and bigger. With a tourniquet, you’re able to achieve the same effect with a much lighter load. (Related: New Study Reveals Yet Another Reason You Should Lift Heavy)

When you lift heavy weights, it creates a localized hypoxic environment in your muscles due to the demand, which just means there’s less oxygen than usual. Hypertrophy training uses load (weight) and reps together to reach fatigue and oxygen depletion faster. When that happens, there’s a buildup of lactate, which is what causes that “burning” feeling when you’re doing a tough workout. Using a tourniquet mimics this hypoxic environment by reducing the blood flow, but without having to actually use heavy weights, says Dove.

“For example, if you would normally have to perform bicep curls with 25-pound weights in order to increase your bicep strength and muscle size, with the use of BFR you would only need to use a one- to 5-pound weight to achieve the same level of strength and hypertrophy (muscle growth).” Research has shown that doing BFR with loads that are 10 to 30 percent of your 1-rep max are sufficient to stimulate muscle growth because BFR simulates the same lower-oxygen environment in your muscles that you’d get by lifting heavier weights.

While this might sound kind of crazy, it’s actually not a new idea at all. “Weight-lifters have been tapping into the benefits of BFR for years,” says Eric Bowman, M.D., M.P.H., assistant professor of orthopedic surgery and rehabilitation at Vanderbilt University Medical Center in Franklin, TN.

In fact, Dr. Bowman says, a form of BFR called Kaatsu training was created by Dr. Yoshiaki Sato after he noticed significant discomfort in his calves from sitting in traditional posture during a Buddhist ceremony in Japan in the 1960s. He realized this felt similar to the burning sensation he felt while working out and started using bands to replicate the effects. “You may have seen weight-lifters at the gym replicating this by wearing bands on their arms or legs,” says Dr. Bowman. Now, BFR is being used all over the world for a variety of purposes.

What are the benefits of blood flow restriction training?

Aside from increased strength (even outside of your BFR sessions) and muscle growth, there are some pretty amazing benefits of blood flow restriction training.

Overall, BFR is a really well-researched method of training. “Most of the published studies have been on small groups of subjects, yet the results are substantial,” says Bowman. Since it’s been around for many decades in one form or another, there’s been a decent amount of investigation into how it works and who should try it. (Related: Common Weight Lifting Questions for Beginners Who Are Ready to Train Heavy)

Here, some example of people who can benefit from blood flow restriction training:

It makes healthy people stronger. In people without injuries, the research-backed benefits include increases in muscle size, strength, and endurance that are similar to high-weight exercise routines, says Dr. Bowman. That means you could lift much lighter weights and still see #gainz.

It also makes injured people stronger. Now, BFR research is being done on people who have recently had operations or who need rehabilitation for one reason or another. A few studies have identified benefits for orthopedic patients, with more currently underway, says Dr. Bowman. “This has the potential to be a major advancement in the way we rehabilitate patients with knee pain, ACL injuries, tendinitis, post-operative knee surgery, and more.” BFR is also used in elderly patients who need to get stronger, but can’t lift heavy weights. (Related: How I Recovered from Two ACL Tears and Came Back Stronger Than Ever)

You can do pretty much any exercise with BFR. Essentially, you can take any exercise you do in your usual workout routine, reduce the weight or intensity, add a tourniquet, and get the same results. “You can do anything you normally would do with the BFR: squats, lunges, deadlifts, push-ups, biceps curls, walking on a treadmill,” says Kellen Scantlebury D.P.T., C.S.C.S., CEO of Fit Club NY. “The possibilities are really endless.”

Sessions are short. “In our clinic, we typically will do one exercise for seven minutes and, at most, will do three exercises total,” says Jenna Baynes, a doctor of physical therapy at Hospital for Special Surgery. In other words, you can get a really great workout in a fraction of the time because you’re using much lighter loads.

Are there any risks to blood flow restriction training?

But before you run out to buy a BFR strap or a DIY BFR kit, here are a few things you should know.

You really need to work with a professional to get started. While, with the proper equipment and a properly trained individual, BFR is very safe, says Dove, “you should not try blood flow restriction training without the supervision and guidance of someone who has specific BFR training and is BFR certified. It would not be safe to attempt to reduce the circulation to your own limbs without knowing how to do it correctly or without a way to ensure that the occlusion pressure stays within a safe level,” she explains.

The reason for this is pretty simple: There can be severe complications to incorrectly applying and using a tourniquet to your limbs, such as nerve damage, muscle damage, and risk of forming blood clots, says Dove. “As with all forms of exercise, your physician should give you clearance based on your medical conditions and history so that you can get stronger in the safest way possible.”

At the moment, in order to perform BFR, you need to be a medical or fitness professional such as a physical therapist, certified athletic trainer, occupational therapist, or a chiropractor who has also passed a blood flow restriction certification class. (Related: How to Make the Most of Your Physical Therapy Sessions)

After practicing with a professional, you may be able to do BFR on your own. In the case of a BFR device that has a pump, Scantlebury says he typically likes to have clients use the device alongside him for at least six sessions before he feels comfortable having them try it on their own. “When using the device for the first time, you need to determine the maximum occlusion levels or the level at which total blood flow is occluded (or blocked) to the extremities.” After your maximum is determined, your therapist or trainer will figure out how much pressure the device should have during your training sessions, which will be less than your maximum.

But even if you’re just using straps with no pump, it can still be difficult to gauge exactly how tight they should be for the best results, and a certified pro can help you determine that. Ideally, they should be tight enough that blood flow is restricted, but not so tight that you can’t move.

It’s not appropriate for everyone. “Anyone with a history of blood clots (also known as deep vein thrombosis or pulmonary embolism) should not participate in blood flow restriction training, says Dr. Bowman. Also, those with significant heart disease, hypertension, vascular disease, poor blood flow, or anyone who is pregnant should avoid BFR training as this may increase the risk of stroke.

The Bottom Line

BFR is pretty awesome for increasing muscle strength and size if you know what you’re doing and you’re being supervised by a pro, but it may not be the best idea to try it out on the first time on your own. If you’re interested in trying it, seek out a physical therapist or trainer with a blood flow restriction certification in your area, especially if you’re dealing with an injury you think BFR could help you come back from. Otherwise, you can still stick with traditional weight training, because the results are pretty hard to argue with.

Benefits Of BFR Training (But Is It Safe?)


Blood Flow Restriction (BFR) training has become popular around the world for increasing muscle mass.

In fact, it’s known to be The Fastest Way To Build Muscles. Many of Professional athletes I personally follow like Abel Albonetti, He also uses the (BFR) training method In his workout routines. People have given it many names like (KAATSU, HYPOXIC TRAINING, OCCLUSION TRAINING).


Blood Flow Restriction: This training method usually is for those who don’t want to lift really heavy weight to build muscle. Expect building muscle from exercising at higher intensities. And with heavier weights, This is the other way of building muscle fast at low intensity. And with lighter weights. However, Some people are still not sure about safety. And confusion seems to be growing day by day.


  • Basically, Blood Flow Restriction training involves wrapping the limb of the muscle that you’re intending to work with. Either with a cuff or wraps to allow the flow of blood to your muscles from your arteries. While preventing the return of that blood back through the vein.
  • It essentially traps a lot more blood in the muscles that you’re working with. And giving you a far greater pump even with lighter weights. Research on blood flow restriction training shows that low-intensity resistance training, Even as low as 20%-To-50% percent of your one rep max can increase muscle size. And also, it can increase muscle strength in the same way as the traditional High-Intensity resistance training can.
  • So If you’re working out at a low-intensity level. Like 20% percent of your one rep max without blood flow restriction training. I’m sure that you won’t be seeing these kinds of results. In fact, You’ll be wasting your time completely.


  • This was proven in one study. That compared regular walking with walking while restricting blood flow to the legs. For the blood restriction group, The thigh muscle cross-sectional area and the muscle volume increased by 4% to 7% percent. And their 1 rep max increased by 8% to 10% percent.
  • On the other hand, The regular walking group experienced absolutely no changes at all. Meaning the blood flow restriction group had statistically significant gains in muscle size and strength.


  • The same thing was demonstrated in another study. Where instead of walking the two groups engaged in low-intensity resistance training at 20% of their 1 rep max. The group with the blood flow restriction experienced more than 5 times the gains in muscle cross-sectional area. They also increase their 1 rep max for squats 8% percent higher than the control group. And 20% percent higher for leg curls.
  • Even though, I prefer high-intensity training with heavy weight. Low-intensity blood flow restriction (BFR) training can be a great way to throw in some different variety into your routine. It can also be great for people who can’t lift heavy-weights due to an injury or some other reason.


Basically, You have to wrap at the top of your leg or at the top of your arm right above your biceps. Wrap only one layer don’t wrap across your whole leg or your whole arm. It should look like it’s one band circling around the same spot. Don’t wrap it as tight as you can. Because That could restrict the blood flow from your arteries defeating the whole purpose. It needs to be snug not unbearably tight. And then you should aim for higher reps with only low-intensity loads. An Example 4x sets each with only 30 seconds of rest in between. The first set should be 30 reps and then the last three should be 15 reps.


Improper wrapping techniques could be led to numbness during (BFR) training Sessions. Learn more about How to do it properly and then, There’s nothing You should be worried about. IT’S SAFE!

Everyone is asking the same question. Blood Flow Restriction Training – Is it safe? Because it doesn’t sound like a safe thing to do. I know that was my first thought and number one concern. I mean, limiting blood flow to an area of the body? How can that be a good thing? Let’s jump into the most common questions and concerns:

By far the most often asked question:

Is it safe to cut off blood flow?

  • Actually, No…but with BFR Training you are not actually fully cutting off blood flow. In fact, the most important element of BFR training is to never occlude the flow of blood into the limb (via the arteries). You are occluding the blood flow out of the limb (via the veins); however, when your muscles pump, the venous blood can be pushed past the restriction of the BFR band (if the band has elastic properties) and continue to provide some level of circulation to the exercising limb.

So, can I just use any strap or band?

  • Ultimately, no – there are several elements that need to be considered with regards to safety when choosing a BFR band
  1. Elastic versus non-elastic
  2. Narrow versus Wide
  3. Pneumatic versus Non-Pneumatic
Elastic vs. Non-elastic:
  • There are elastic materials like resistance bands or elastic wraps
  • There are non-elastic materials like nylon straps or cuffs
  • Elastic devices have properties that “give” (or stretch) when force is applied to them
  • Non-elastic devices don’t stretch, when force is applied to them
Narrow vs. Wide
  • For all the BFR products on the market there is a range of widths from 1 inch to 10 inches
  • The wider the belt/band/cuff, the less pressure or force it takes to occlude the arterial blood inflow into an extremity
  • Wider cuffs (up to 18 cm) have shown increased heart rate, increased blood pressure, greater perceived effort and higher ratings of pain – when compared with narrow cuffs (as low as 3.0 cm) when inflated to the same restrictive pressure
  • Also important to note: wider cuffs transmit pressure to a moving limb differently than narrow cuffs
  • Narrow bands, however, can be limited in their ability to adequately restrict blood flow, as well as may be more likely to involve nerve compromise
Pneumatic versus Non-Pneumatic
  • Basically, can you control the amount of force applied to the band? Pneumatic means air inflating the device. Without this input, you cannot control the amount of restriction you are applying to monitor from session to session. More restriction is NOT shown to be better or more effective! However, some level of effectiveness is tied to amount of restriction, so without a pneumatic device, you can never know how much you are restricting your blood flow.

What are the risks?

Most commonly, no side effects are experienced with BFR training differently than traditional exercise. A study by (Nakajima et al., 2006 & Yasuda et al., 2017) found:

“Symptoms such as dizziness, subcutaneous hemorrhage and numbness” as the primary findings, but “there were no serious side effects (pulmonary embolism, paralysis by nerve compression, rhabdomyolysis, venous thrombosis, or pulmonary infarction).”

In other words, this study concluded that with “proper training leaders and instructors can achieve beneficial effects without serious side effects.”

Safety (what elements make BFR safe):

What we DON’T want What we DO want
We DON’T want to fully occlude arterial inflow to an extremity We DO want to impede venous outflow
We DON’T want to damage muscle, vessels, nerves or other tissues We DO want to be able to control the amount of restriction
We DON’T want to cause pain or discomfort to the patient/client We DO want to allow muscles to contract and exercises to be unhindered

Ultimately, we want to set up a mismatch between enough blood getting to the muscles so they can meet the needs of sustaining work, but limit the blood flow the muscle can get to create a disturbance…but do so safely. Ideally, it would be nice to design a BFR product so that it can be used anywhere, anytime, by anyone. It would be even better it that device were affordable.

So, can we accomplish all of these things?

  • Development of pneumatic bands for precise control of pressure
  • Designed for intermediate width to distribute the force, but cover as little muscle as possible, thus being comfortable to wear and not blocking the function of the activities being completed
  • Provision of elasticity to allow for muscular expansion and swelling while maintaining restriction, but still allowing some level of blood flow
  • Ideally it wouldn’t interfere with any activity or sport

B STRONG’s design has been engineered to address all of these elements. It incorporates a pneumatic inner layer of inflatable chambers that can evenly distribute the pressure across each chamber – The compressibility of which provides the elasticity to allow some level of “give”, making full occlusion extremely difficult to virtually impossible. The adjustable outer layer allows accommodation in size (Cross Sectional Area – CSA) of the limb. Having all of these elements allows B STRONG to achieve appropriate, safe, comfortable and versatile options for blood flow restriction training.

So, what are the primary contraindications (reasons to withhold treatment due to the harm that it might cause)? In other words, what conditions or situations would limit one’s ability to use BFR Training?

It has been suggested that persons not utilize BFR with these circumstances:

  • Cardiac disease
  • Active cancer
  • Pregnancy
  • Have a history of deep-vein thrombosis (blood clots)
  • Unregulated/uncontrolled high blood pressure
  • Systemic lymphedema

While not “contraindicated”, caution should also be used with those who have Peripheral Vascular Disease or Peripheral Neuropathy, too.

While all of these considerations are HIGHLY valued to ensure safety and proceed at the highest level of caution, there are several studies showing effectiveness and safe utilization of BFR in several of these “at risk” populations. When in doubt, consult medical professionals on an individual basis!

Another common question I am often asked:

It is only safe if it is FDA “approved”?

The short and overwhelming answer to this is, NO!

I will attempt to BRIEFLY elaborate:

  1. First, the VAST majority of the research (and virtually all of the cited publications on safety) are NOT using FDA “approved” systems/units
  2. As far as the FDA “approval”, let me elaborate
    • As long as a device meets the pre-existing criteria (thus already deemed safe) and has been determined to be basically equivalent to another legally marketed device, the device is already “approved”…no additional safety, effectiveness or testing is therefore required
    • If a company is using an already “approved” device, they qualify for a 510K exemption and only needs to “list” their product with the FDA
    • An example of a type of product meeting pre-existing criteria would be that of a Class I device – The FDA places their medial devices into classes:
      • Class I (lowest risk)
      • Class I
      • Class III (highest risk)
    • Class I devices – are deemed to have low potential for harm to the user. Most of these devices are exempt from pre-market review, including pneumatic tourniquets. Furthermore, if a pneumatic tourniquet is not used in surgery (like with its use for BFR), it considered an “off label” use
    • Off label uses are perfectly acceptable to be implemented if a clinician feels it would be: “Potentially beneficial for the patient”
  3. So, as long as a device is used in the intended use of a legally marketed device and not modified to operate using a different scientific technology it does not need any additional pre-market approval (because a similar device has already been “approved”)
  4. This means that any endorsement of a BFR device having FDA “approval” may be somewhat technically accurate, but mostly misleading

To summarize everything –

Since we are talking about safety in as many populations as possible, stopping blood flow to a limb for some additional potential benefit is not currently advised. While some research is developing that supports full occlusion for a brief period of time, it is NOT shown to be more effective than utilization of BFR without full occlusion. Furthermore, evidence show similar effects from lower levels of restriction, so the ability to fully occlude arterial flow and then back off to an arbitrary percentage of limb occlusion provides no additional benefit or safety measures.

Lastly, we have all understood for a long time now that pooling of blood in the body comes with risk. Gaining a training effect from potentially riskier practice does not make sense…especially since limiting blood flow to tap into the body’s natural systems of response to exercise/stress/recovery can happen without fully occluding blood. After all, the primary emphasis is muscular fatigue at lower forces and demands while minimizing risk…this remains the most important element.


I am a certified trainer, instructor & ambassador of BStrong BFR Training Systems


    1. T. Nakajima, M. Kurano, H. Iida, H. Takano, H. Oonuma, T. Morita, K. Meguro, Y. Sato, T. Nagata (2006). Use and safety of KAATSU training: Results of a national survey. (2008) International Journal of KAATSU Training Research, 2(1):5-13
    2. Yasuda T, Meguro M, Sato Y, Nakajima T (2017). Use and safety of KAATSU training: Results of a national survey. International Journal of KAATSU Training Research, 13: 1-9.
    3. Loenneke JP, Wilson JM, Wilson GJ, Pujol TJ, Bemben MG (2011). Potential safety issues with blood flow restriction training. Scandinavian Journal of Medicine & Science in Sports, August; 21(4):510-8.
    4. Clark, B. C., et al. (2011). Relative safety of 4 weeks of blood flow-restricted resistance exercise in young, healthy adults. Scandinavian Journal of Medicine & Science in Sports, 21(5), 653-662.
    5. Loenneke JP, Fahs CA, Rossow LM, et al. Effects of cuff width on arterial occlusion: implications for blood flow restricted exercise. European Journal of Applied Physiology. 2012;112(8):2903–12.
    6. Rossow LM, Fahs CA, Loenneke JP, et al. Cardiovascular and perceptual responses to blood-flow-restricted resistance exercise with differing restrictive cuffs. Clinical Physiological and Functional Imaging. 2012;32(5):331–7.
    7. Loenneke JP, Balapur A, Thrower AD, Barnes JT, Pujol TJ. The perceptual responses to occluded exercise. International Journal of Sports Medicine. 2011;32(3):181–184.
    8. Loenneke JP et al, Blood flow restriction pressure recommendations: a tale of two cuffs. Frontiers in Physiology. 2013; 4: 249.
    9. Tanaka Y & Takarada Y. (2018). The impact of aerobic exercise training with vascularocclusion in patients with chronic heart failure ESC Heart Failure: March (5) 586–591.

    10. Madarame H, Kurano M, Fukumura K, Fukuda T, Nakajima T. (2013). Haemostatic and inflammatory responses to blood flow-restricted exercise in patients with ischaemic heart disease: a pilot study. Clinical Physiology & Functional Imaging. Jan;33(1):11-7.

    11. Neto GR, Novaes JS, Dias I, Brown A, Vianna J, Cirilo-Sousa MS (2017). Effects of resistance training with blood flow restriction on haemodynamics: a systematic review. Clinical Physiology & Functional Imaging Nov; 37(6):567-574.

BFR, the monster rocket that will cost SpaceX roughly $5 billion to develop, has a new name.

SpaceX CEO Elon Musk tweeted late Monday night that he has renamed the company’s largest (and yet to be built) BFR rocket to Starship. Or more precisely, the spaceship portion will be called Starship. The rocket booster used to propel Starship from Earth’s gravitational grasp will be called Super Heavy.

Starship Super Heavy.

Renaming BFR to Starship

— Elon Musk (@elonmusk) November 20, 2018

Technically, two parts: Starship is the spaceship/upper stage & Super Heavy is the rocket booster needed to escape Earth’s deep gravity well (not needed for other planets or moons)

— Elon Musk (@elonmusk) November 20, 2018

The BFR, meant to stand for Big Falcon Rocket or, ahem, anything else that might spring to mind, is designed to be a sustainable interplanetary spaceship. It will eventually replace SpaceX’s other rockets such as Falcon 9 and Falcon Heavy.

But as one of Musk’s Twitter followers noted, “unless this starship is sent on a mission to another star system it can’t be called a starship.” Musk upped the stakes for an already complex and costly project that is in its earliest stages by responding, “Later versions will,” presumably meaning that the future iterations of the Starship will leave our star system. The closest star system to our sun is the Alpha Centauri system, which is about 4.3 light-years from Earth.

Later versions will

— Elon Musk (@elonmusk) November 20, 2018

The BFR has not yet been built; it’s in the early stages of development. And it has a long way to go — and by just about every measure, including investment. (Just 5 percent of SpaceX’s resources are currently dedicated to the BFR, according to Musk.)

Still, the company has made some progress. SpaceX signed Japanese billionaire entrepreneur Yusaku Maezawa to be the first private citizen to take a flight around the Moon in the BFR, a 240,000-mile journey slated for as early as 2023.

SpaceX is on its third design for the rocket, which Musk presented in September with a number of new details.

The design, which depicted a 118-meter-long two-stage reusable spaceship capable of taking a 100-metric-ton payload to Mars, is “the final iteration in terms of broad architectural designs for BFR,” Musk said in September.

You don’t have to lie when talking to your kids about SpaceX’s BFR Mars-colonization architecture.

Yes, BFR stands for “Big F—ing Rocket.” But there’s also a family-friendly variant of the acronym, and it’s coming into wider and wider use — as evidenced by SpaceX President Gwynne Shotwell’s remarks Thursday (Oct. 5) at the first meeting of the newly resurrected National Space Council.

“Last week, Elon announced — or, basically, gave an update on — the Big Falcon Rocket program, Big Falcon Rocket and Big Falcon Spaceship,” Shotwell said, referring to SpaceX founder and CEO Elon Musk’s Sept. 29 presentation at the International Astronautical Congress (IAC) in Adelaide, Australia.

The BFR transportation system consists of a giant, 31-engine rocket topped by a spaceship capable of carrying 100 people or more. Both of these vehicles will be fully and rapidly reusable, helping to make Mars colonization economically feasible, Musk said during his IAC talk.

SpaceX has already started serious development work on the BFR, and the company aims to launch the first uncrewed Mars missions with it in 2022, Musk said. If everything goes well, crewed BFR flights to the Red Planet could follow in 2024, he added.

Musk first revealed the basics of SpaceX’s Mars-settlement architecture at the 2016 IAC meeting, which was held in Guadalajara, Mexico. During that presentation, the billionaire entrepreneur called the rocket-spaceship combo the Interplanetary Transport System.

With the shift to BFR, SpaceX appears to be going back to the system’s nomenclatural roots; the term has been in use internally at the company for several years, as a December 2015 GQ story makes clear.

“This is a very obtuse video-game reference,” Musk told GQ. “In the original Doom, the gun that was like the crazy gun was the BFG 9000 or something like that. So it was sort of named after the gun in Doom. But that’s not its official name, of course.”

This anecdote suggests that “Big F—ing Rocket” was the original phrase for the BFR acronym. But “Big Falcon Rocket” isn’t exactly an awkward fit: The big booster slots nicely into SpaceX’s Falcon family, which also includes the company’s first orbital rocket, the now-retired Falcon 1; the workhorse Falcon 9; and the Falcon Heavy, whose maiden flight is scheduled to take place next month.

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on

Elon Musk is building a spaceship that’s so ambitious that some experts are calling it ‘science fiction.’ Here’s what SpaceX and its engineers are up against.

  • Elon Musk plans to blast a tourist around the moon in a ship made by his rocket company, SpaceX.
  • The private lunar mission is meant to demonstrate a new two-part launch system called Big Falcon Rocket, which is designed to eventually bring humans to Mars.
  • Engineers are building a prototype of the BFR’s spaceship primarily out of carbon-fiber composites.
  • Exactly how SpaceX is building that spaceship isn’t publicly known, but industry experts have some guesses based on a handful of images.
  • Aerospace engineers, astronauts, and Musk himself have said the first missions to Mars are likely to be perilous.
  • This story was originally published on September 16, 2018. It has been revised and updated following a September 17 press event about SpaceX’s planned moon mission, in which Elon Musk shared new information and images about the company’s BFR launch system.

In December, a giant white tent appeared at the Port of Los Angeles. A routine permit suggested that SpaceX, the rocket company founded by Elon Musk, was using the roughly 20,000-square-foot $500,000 facility as a “storage tent.”

But Musk revealed the tent’s true purpose a few months later. Inside, his engineers are building a colossal interplanetary spacecraft called the Big Falcon Rocket (BFR or, as Musk has said, Big F—ing Rocket).

On September 17, SpaceX named its first private passenger to be launched in the BFR: Yusaku Maezawa, a Japanese billionaire and art collector. Maezawa plans to fly around the moon and take a crew of up to eight artists with him on a week-long mission called “#dearMoon.”

The BFR construction project marks the incredible and unorthodox beginning of an effort by SpaceX to colonize Mars. Musk’s larger goal, which he has described as “aspirational,” is to launch an uncrewed cargo mission to the red planet in 2022, followed by human missions in 2024.

“He wants to have two planets for humans to live on. Some people call it crazy, but it kind of makes some sense,” Marco Cáceres, a senior space analyst at the Teal Group, told Business Insider. “If something were to happen to our planet, we have an option.”

In his recent announcement, Musk revealed new renderings of the BFR and images of its hardware.

“We’re already building it,” Musk said, adding that the company has settled on “the final iteration in terms of broad architectural design.”

SpaceX is said to be building a prototype Mars spaceship inside a 20,000-square-foot tent at the Port of Los Angeles. Google Earth Pro; Samantha Lee/Business Insider

The two-part BFR will consist of a 180-foot-tall spaceship, including three protruding fins, that sits atop a 230-foot-tall rocket booster. Stacked together, the system is expected to stretch nearly 39 stories high. That is nearly 100 feet taller than the Statue of Liberty and 23 feet taller than NASA’s Saturn V rocket, which launched Apollo astronauts to the moon.

When fully fueled, BFR may weigh perhaps 9 million pounds, lift up to 150 tons of cargo, and ferry as many as 100 passengers to Mars.

On top of all that, the entire system will be 100% reusable.

That’s something “we haven’t seen, ever,” Cáceres said. “This would be the first entirely reusable launch vehicle.”

An illustration of SpaceX’s BFR launching toward space. SpaceX

Musk’s vision for the BFR places it among the most difficult engineering projects ever attempted by humans.

“We’ve gone to the moon. But this is an order of magnitude at least more ambitious than that — probably a couple,” Steve Nutt, a professor of chemical, aerospace, and mechanical engineering at the University of Southern California, told Business Insider. “It just sounds like science fiction.”

So far, SpaceX has mostly kept secret whatever is going on under that white tent. People who work there will not reveal details of the project, nor will the few lucky outsiders who’ve been given a tour. The company declined to provide interviews or comments for this story.

So aerospace experts and the public are left asking how SpaceX, a private company, could possibly build the enormous spaceship Musk has envisioned on the timelines he’s put forth.

To get as close as possible to an answer, we spoke with a handful of aerospace industry experts who have ideas about how SpaceX will construct the BFR — including potential building materials, cutting-edge assembly processes, safety checks, and projected costs.

But they also have big questions, perhaps the most important of which is: Is society prepared to accept the high probability that some of SpaceX’s missions to Mars will end in tragedy?

Will 2019 be the year of the first Mars spaceship?

Musk at the International Astronautical Congress last September in Adelaide, Australia. Mark Brake/Getty Images

Musk has said the BFR system will eventually replace every rocket and spaceship that SpaceX uses today, since it should be inexpensive to launch relative to the single-use rockets that dominate the industry.

Right now, less than 5% of SpaceX’s resources are being spent on BFR, Musk said, because the company is focused on launching its first NASA astronauts in 2019 and establishing Starlink: a constellation of 12,000 satellites designed to cover Earth in high-speed internet access.

But more and more of SpaceX’s 6,000-7,000 employees will likely be directed into the BFR effort as soon as the end of 2019.

For now, engineers have started with “by far the hardest” part of the system to get right, as Musk has described it: the 18-story spaceship. The first prototype should be completed in 2019, according to Musk.

Assuming construction began with the tent’s completion around December — tools for making pieces of the fuselage, or body of the spaceship, rolled through the tent’s flaps months ago — this would mean a build time of about 18 to 24 months. By comparison, NASA’s space shuttle orbiters, which are smaller than a BFR spaceship, each took about five years to make.

“It’s typical SpaceX and Elon Musk stuff,” Nutt said. “You don’t sit around. There’s a lot of pressure to do things quickly.”

Once built, the spaceship prototype may ride on a barge through the Panama Canal and get dropped off at the Texas coast near Boca Chica, where SpaceX is developing a launch facility. There it would start a series of short “hop” tests by late 2019, Gwynne Shotwell, the company’s president and COO, indicated during a conference earlier in September.

Around the same time, workers could finish constructing SpaceX’s permanent BFR factory in the Port of Los Angeles. That facility will be about 200,000 square feet, 10 times as large as the white tent.

When all the parts are ready, according to SpaceX’s plans, the booster will heave the spaceship dozens of miles above the ground, detach, then land itself for inspection and refueling. Meanwhile, the spaceship will fire its engines to accelerate into orbit around Earth. (Shotwell said this may happen as soon as 2020.)

A diagram showing how SpaceX plans to establish a base and methane-fueling depot on Mars. Elon Musk/SpaceX; New Space/Mary Ann Liebert, Inc. Publishers

The ship will be nearly out of fuel by that point, though, so SpaceX plans to launch nearly identical tanker spaceships to meet up with the first one in orbit. A series of rendezvous at about 17,500 mph would refill the spaceship’s tanks with liquid methane fuel and the liquid oxygen required to burn it, but this might take about a dozen tanker flights.

“That allows us to effectively reset the rocket equation,” Paul Wooster, SpaceX’s principal Mars-development engineer, said during a presentation to the Mars Society in August. “We go from getting 100 tons or more into low-Earth orbit, then refill, and we can take that payload pretty much anywhere — including the surface of Mars.”

Musk’s vision of a city on Mars. SpaceX/YouTube

The BFR’s spaceship is also designed to be refilled with fuel on Mars to power its return to Earth. SpaceX plans to manufacture oxygen and methane fuel using water from Martian soil, carbon dioxide in the planet’s thin air, and electricity from solar panels.

A carbon-fiber emissary from Earth

An illustration of SpaceX’s Big Falcon Spaceship landing on Mars. SpaceX

To be able to launch, refuel in orbit, endure months of flying through space, land on Mars, leave that planet, and safely return to Earth — then do all that over again — the BFR can’t be an ordinary spacecraft.

That’s why Musk is planning to build the entire spaceship “primarily of an advanced carbon fiber,” he said in 2016.

Carbon-fiber composites are made out of nearly microscopic yet superstrong threads of carbon. The filaments, which are often woven together into a fabric, are then set in sticky, glue-like epoxy. When cured by heat, the epoxy hardens into an ultratough resin around the fibers.

A carbon-fiber strand tied in a knot. Tour Group/Rice University

The whole is greater than the sum of its parts. Many carbon-fiber composites can match or exceed the properties of steel using one-fifth of the material. Some variants can also meet the properties of aluminum — the aerospace industry’s go-to lightweight building material — at half that metal’s mass.

But it’s not easy to build huge structures from carbon fiber, and what SpaceX is constructing is unprecedented in the history of aviation and spaceflight.

The largest comparable vehicle ever made would be Boeing’s 787 Dreamliner commercial jet airplane. But such jets are about 50% composites by weight, travel dozens of times slower, and don’t leave Earth.

The spaceship, Cáceres said, “will be massive — much bigger than anything we’ve ever seen.”

Musk revealed the first clues about how SpaceX would manufacture a carbon-fiber vessel in April. That’s when he shared a photo of a 40-foot-long metal cylinder with a seemingly tiny Tesla car next to it for scale.

“SpaceX main body tool for the BFR interplanetary spaceship,” Musk said on Instagram. (He has since deleted his account.)

A tool roughly 30 feet in diameter that SpaceX is using to build its Big Falcon Rocket spaceship. Elon Musk/SpaceX; Instagram

That tool is a rotating machine called a lathe or mandrel, Nutt said, which is used to build carbon-fiber structures.

“It’s a really, really big one,” Nutt said of the mandrel. “I’ve never seen one close to that big.”

Mandrels work something like a thread spooler. A robot moves along the length of a rotating mandrel, precisely unwinding rolls of carbon-fiber tape and wrapping them around the cylinder.

Many carbon-fiber tapes are woven fabric. But Nutt thinks SpaceX engineers are wrapping the mandrel in an unwoven version that provides the “highest stiffness and strength,” since it crams the largest number of fibers into a given volume and won’t easily kink or wrinkle (which can weaken a structure).

“You lay layer upon layer of the material. If you’re going to make a spacecraft part, you’d probably have dozens of layers of material on top of each other,” Greg Autry, the director of the Southern California Spaceflight Initiative who’s a leading expert on the space industry, told Business Insider. (Autry has a nondisclosure agreement with SpaceX but offered to speak about the aerospace industry in general.)

Only Boeing has ever used a mandrel close to the size of the tool in Musk’s photo.

‘The complexity is daunting’

The exact materials and methods SpaceX is using aren’t publicly known, but Nutt said several big challenges loom if you’re making carbon-fiber structures the size of apartment buildings.

One is that epoxy slowly cures on its own at room temperature. Each epoxy has a different cure rate, but the kind used to manufacture airplanes becomes unusable after about four weeks, according to Federal Aviation Administration regulations. That means SpaceX would get only about a month to build each major section of the spaceship.

Another challenge is that carbon-fiber composites don’t like to touch super-cooled, or cryogenic, liquids. But to remain a liquid, methane must be kept below -259 degrees Fahrenheit and oxygen below -297 degrees.

The stakes of that challenge became clear in 2016, when one of SpaceX’s Falcon 9 rockets exploded on a launchpad while carrying a $200 million satellite. The most likely cause: the bursting of a carbon-fiber-wrapped tank filled with cryogenic liquid.

“It’s subject to cracking and leaking,” Musk said during a presentation after the explosion.

Inside SpaceX’s giant carbon-fiber tank. SpaceX/Elon Musk

But Musk said last year that SpaceX had “developed a new carbon-fiber matrix that’s much stronger and more capable at than anything before.”

To demonstrate that technological breakthrough, SpaceX built the biggest-ever carbon-fiber-composite fuel tank, then Musk’s staff tied it to a barge, dragged it to sea, filled it with cryogenic liquid, pressurized it beyond its limits, and made the tank violently burst.

A carbon-fiber tank 40 feet in diameter that SpaceX made in 2016. Elon Musk/SpaceX

Then there’s another major challenge in building most of a spaceship out of carbon-fiber composites: If the material isn’t cured correctly, hard-to-detect and potentially mission-ending flaws might get cooked into the spaceship’s body.

To avoid such disastrous defects, carbon-fiber composites must get squeezed under as much pressure as possible to push out bubbles, collapse voids, and ensure strong bonds.

“That’s typically done with a giant pressurized oven, like a pressure cooker, that’s called an autoclave,” Autry said. “But these things are very expensive.”

Cáceres said an autoclave the size SpaceX might require would be a similar size to the one used for 787 airplane fabrication. That custom-built device cost Boeing as much as $300 million. So Nutt thinks SpaceX is likely to go about it a different way.

“You can make an oven for one-half to one-tenth the cost of an autoclave,” Nutt said. A huge “heat blanket,” which would wrap around the mandrel, is perhaps another cost-effective option.

Inside a mandrel or lathe that SpaceX uses to wind carbon-fiber-composite barrel sections of the company’s Big Falcon Rocket, or BFR. SpaceX

If he’s right, that means SpaceX would put each finished section into a giant heat-resistant plastic bag, suck out enough air to smoosh the carbon-fiber layers together, and heat everything. Once cured and hardened, workers would disassemble the mandrel from the inside.

Indeed, newly released images show the BFR’s tooling (above) and the first cured and hardened cylinder made of carbon-fiber composites (below).

A completed carbon-fiber-composite barrel section of SpaceX’s Big Falcon Rocket, or BFR. SpaceX

When all the big pieces are done — perhaps two or three “barrel sections,” as Wooster calls the cylinders, plus a pointy nosecone — SpaceX would somehow combine them all into a single fuselage.

To join the sections of Boeing’s Dreamliner together, the company uses about 50,000 metal fasteners. But initially this led to major headaches, since thousands of fasteners had to be replaced on about a dozen of the earliest planes after problems appeared during pressurization tests.

Japanese billionaire and lunar tourist hopeful Yusaku Maezawa stands inside a completed carbon-fiber-composite barrel section of SpaceX’s Big Falcon Rocket, or BFR. Yusaku Maezawa/Twitter Fasteners are more problematic for a spaceship. Temperature differences in space can be hundreds of degrees, and various aerospace materials expand and contract at different rates.

“There are so many different parts of this thing, the complexity is daunting,” Nutt said. “There will have to be a variety of materials and joining methods to accomplish everything this has to accomplish.”

Nutt said this would be all the more reason for critics to laud any triumphs by SpaceX.

“I think if he succeeds, then people should appreciate what he had to overcome — what the company had to overcome,” Nutt said, adding, “I wouldn’t recommend betting against Elon Musk.”

How to avoid death by defect or damage

Whatever is going on under that big white tent, one thing is certain, Nutt said: SpaceX needs to very carefully check its work.

That’s because carbon-fiber composite materials don’t easily signal cracks, voids, or other defects.

“When a metal part gets damaged, there’s usually a dent or a scratch or something like that,” Nutt said. “With composite parts, there can be damage and no manifestations at the surface. It’s all subsurface.”

To inspect carbon-fiber sections, SpaceX may need to painstakingly cover every square inch with ultrasound scanners.

“You may have some structural problems on an aircraft, but the aircraft won’t explode,” Cáceres said. “But on a rocket, leaks, cracks, and instability — those things can be catastrophic. It explodes and people die.”

Workers look over carbon-fiber composite materials for Boeing’s 787 Dreamliner. Boeing

Nutt thinks that to reduce that risk, SpaceX is likely following an industry-standard practice of making demonstration parts, cutting out foot-long sample pieces, torturing those in stress tests, and then inspecting them. Engineers could feed that test data into computer models and simulators to estimate how a full-size spaceship might fare (and change its design accordingly).

“It’s a fairly tedious process, and that’s one reason materials in aerospace are introduced extremely slowly,” Nutt said.

Eventually, SpaceX will build and test a full-scale spaceship. And there’s a good chance the first one will fail spectacularly.

“When you’re building something this big, the only real way to test it is once you’ve completed it, and you launch it,” Cáceres said. “You better have a lot of money, because you’re probably going to go through a lot of big, big structures before you get the one that works.”

A SpaceX Grasshopper rocket explodes in midair in August 2014 after an engine sensor failure. SpaceX/YouTube

SpaceX is not under any delusions about avoiding snags. Many of its experimental launches and landings have ended in fiery explosions. The company has also weathered failures with operational rockets that resulted in the loss of expensive payloads. And earlier this year, Musk warned that SpaceX’s largest-ever rocket, Falcon Heavy, could blow up during its maiden launch. (It did not.)

“It’s not 100% certain that we succeed in getting this to flight,” Musk said of the BFR on September 17. “But we’re going to do everything humanly possible to bring it to flight as fast as we can and as safely as we can.”

He added that, starting around 2020, SpaceX plans to launch “many” uncrewed test flights before flying Maezawa to the moon.

“Knowing Elon, I think you can expect him to experiment and do iterative testing — he always has — and it may work, or it may not,” Autry said.

Once the spaceship has embarked on a mission to Mars, however, in-flight inspections and repairs would still be essential.

“It’s such a long mission,” Nutt said. “I think the chances of some kind of damage or failure en route are much greater than a mission of days or weeks that we’ve seen in our lifetime.”

Tiny pieces of rock or comet dust are extremely dangerous in space, since they can impact a spacecraft at thousands of miles per hour. One strike by a millimeter-long object could cripple a deep-space mission if it doesn’t have repair capabilities.

“Those things can go right through any kind of structure and do a lot of damage,” Nutt said. (The video below shows a 0.1-inch aluminum sphere plowing through a carbon-composite material at 15,800 mph.)

Yet carbon-fiber composites are extraordinarily tricky to fix, even on Earth. For example, Nutt said, when the Department of Defense (DoD) needs to repair carbon-fiber-composite jet fighters, workers sand and sheen a damaged area, slather on layers of epoxy using “fancy trowels,” put the patched area under vacuum, and heat it. And that’s what he calls the “crude” method.

“Things that you might be able to repair with some difficulty on Earth are orders of magnitude more difficult to execute and accomplish in space,” Nutt said. “It’s a big structure with a lot of components. The chances of failure are not zero. So you have to worry about those things and have contingency plans for all of them.”

Spaceships don’t grow on trees

An illustration of a BFR spaceship docked at the International Space Station. SpaceX/YouTube

Cáceres said each BFR launch might cost in the tens of millions, give or take, with most of that going toward fuel (since the system is designed to be reused many times). By comparison, the Falcon Heavy rocket costs close to $100 million per launch but can carry about half the payload of a BFR spaceship.

However, Cáceres’ estimate doesn’t include the capital needed to build and test the BFR in the first place.

“If I had to venture to guess, I would say it would be somewhere in the $4 billion to $5 billion range,” Cáceres said of those development costs, adding that if Musk “is really unlucky and there continue to be setbacks, it could be more than that.”

Musk confirmed Cáceres’ guess on Monday, saying the BFR development program should cost about $5 billion, but may cost as much as $10 billion.

Delays can add enormously to the final bill, Cáceres said.

“That’s why so many government space programs tend to be so expensive — because they just go on and on, forever and ever, for technical reasons as well as budgetary and political reasons,” he said. “When I look at NASA and DoD estimates, I look at them with skepticism because they’re looking at cost under ideal conditions. So I usually multiply by a factor of 10.”

SpaceX’s rendering of a Big Falcon Rocket spaceship carrying a passenger around the moon. SpaceX/Twitter

SpaceX raised $507 million in a recent round of series-I funding, a large chunk of which may go toward the BFR project.

Space tourism also appears to be a viable revenue stream. Musk said that an undisclosed sum paid by Maezawa will go toward BFR’s development. However, it’s not clear if and how much of Maezawa’s down payment was part of SpaceX’s recent round of fundraising.

Cáceres expects that if SpaceX shows enough progress, NASA could become interested and invest in the system’s development, further helping to offset the company’s costs.

“Ultimately, BFR could become a joint US government–SpaceX program,” Cáceres said. “That would be my guess, eventually, because as much as I admire the success of SpaceX, this just seems like something too massive and too complicated for one company alone to handle.”

If SpaceX successfully flies a tourist around the moon, it could serve as an audacious advertisement to NASA and lawmakers who control the government’s purse strings: “Buy me,” it would say.

‘Rockets are going to explode, and people are going to die’

An illustration of SpaceX’s Crew Dragon spaceship, also known as Dragon 2 or Dragon V2, orbiting Earth. Kennedy Space Center/SpaceX via Flickr

Before BFR is built and a passenger is launched toward the moon, SpaceX must ace a more immediate task.

For the first time in its 16-year existence, the company is about to launch NASA astronauts to the International Space Station.

“If BFR is going to work, then using Falcon 9 or Falcon Heavy rockets to launch a crewed capsule has to be successful,” Cáceres said. “SpaceX has got to get into a rhythm where launching people to the space station becomes a matter of habit.”

Nine astronauts will fly the first four crewed missions inside SpaceX and Boeing’s new spaceships for NASA, called Crew Dragon and CST-100 Starliner, respectively. David J. Phillip/AP

But even if those crewed flights go smoothly, the world must be prepared for an uncomfortable and inevitable moment: death on, or en route to, Mars and the moon.

“To be clear, this is dangerous. This is no walk in the park,” Musk said of the planned BFR moon mission on Monday. “When you’re pushing the frontier, it’s not a sure thing. It’s not like taking an air flight somewhere — there’s some chance that something could go wrong.”

When Musk presented his plan to reach Mars to the International Astronautical Congress in 2016, an audience member asked who the first people to go on SpaceX’s Mars mission should be.

“The first journey to Mars is going to be really very dangerous. The risk of fatality will be high; there’s just no way around it,” Musk said, adding unequivocally, “It would be basically: Are you prepared to die? And if that’s OK, then you’re a candidate for going.”

Cáceres, who was watching the presentation, said he was struck by Musk’s honesty.

“I immediately thought: That’s not something that any representative, any CEO from a company, or any NASA administrator would say,” Cáceres said. “That’s about as blunt as you can be, and I think he was being very truthful.”

Is Earth ready for a trail of death leading to the red planet?

Mars is about 140 million miles from Earth. ISRO/ISSDC/Emily Lakdawalla (CC BY-NC-SA 3.0)

A significant chunk of the US population now considers sending people to the space station to be somewhat routine and fairly safe, minus two deadly space shuttle accidents, Cáceres said. But the early days of the commercial railroad, automobile, and aviation industries were very deadly.

Cáceres said we should expect a similar outcome if SpaceX is to achieve its goal of making interplanetary travel similarly commonplace.

“SpaceX is going to fail in the future — rockets are going to explode, and people are going to die,” he said. “That is what everyone has to totally understand.”

Chris Hadfield, a retired astronaut, has compared the dangers of using current technologies to reach Mars to an even earlier period of human history, when explorers circumnavigated Earth on perilous, yearslong ocean voyages.

“The majority of the astronauts that we send on those missions wouldn’t make it,” Hadfield told Business Insider of attempts to reach Mars. “They’d die.”

Seasoned astronauts would be likely to attempt the trip regardless. But Cáceres wonders how deep our own enthusiasm for reaching toward the stars actually runs.

“If we want to actually open space to average people rather than government astronauts, then we’ve got to accept that there’s going to be a lot of fatalities,” he said. “We can either decide that that’s acceptable or it’s not, in which case we don’t explore space any more than we have already.”

Are you a current or former SpaceX employee with a story to share? Send Dave Mosher an email or consider more secure options listed here.

Correction: A previous version of this story misstated SpaceX’s planned location for BFR hop tests. A coastal site in Boca Chica, Texas, is the current location being eyed for these launches, not the company’s inland test facility in McGregor.

The Best Blood Flow Restriction Bands and Devices

17 Aug The Best Blood Flow Restriction Bands and Devices

Posted at 21:11h in Exercises, Injury Prevention, Physical Therapy by zlongdpt

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The Best Blood Flow Restriction Bands

I am frequently asked about the best devices for performing blood flow restriction training. As with any trend in the fitness world, many manufacturers have come out with products recently. And like most fitness tools, the best device is highly related to your goals. Unfortunately, some devices on the market have the potential to cause more harm than good, so choosing the appropriate device is needed for both your health and for consistency of performance.

Download The Blood Flow Restriction Guide

Download the e-book that teaches you how to implement blood flow restriction training now!

In this, the first of three articles coming out on blood flow restriction training we will cover the first step in BFR…choosing the right device. Choosing the right device based on your goals and safety needs is the first and most important step in implementing BFR into your training or rehab program.

Disclosure: some of the below links are affiliate links. No products inclusion decisions were made based on affiliation.


First up, and most commonly used are various compression bands to occlude blood flow. These bands have one really great advantage in that they are very cheap (or even free if you have some lying around). The athlete wraps his or her extremity with a compression band at 4-5/10 intensity for the upper arm or 6-7/10 intensity for the legs is most commonly prescribed.

The major drawback of these compression bands is that they cannot be reliable performed in multiple workouts at the exact same level of occlusion. It makes standardizing the level of pressure very difficult. Thus, one workout may be super intense at the prescribed weight and reps while the next may be unbelievably easy.


Up next, you’ll find various commercially sold blood flow restriction bands. Again, these are a cheap option but have two bid drawbacks. The level of occlusion with these again cannot be reliably reproduced. More importantly, many of these bands are very thin. Thus, the pressure of the band is put through a much smaller area, risking injury to the underlying nerves. In fact, on several occasions, these bands have create nerve paralysis. So, if you are buying one of these bands, please choose one that is thick, preferably covering about ¼ to 1/3 of the extremity.

The Edge BFR Device

The Edge BFR System has been recently released and does a great job of addressing the above problems. It is essentially a specialized blood pressure cuff designed for blood flow restriction training for home use. At only $99 it’s a great deal given that the sphygmamometer on the device allows the individual to measure the level of pressure. This means workouts will be more standardized to the individual and the same amount of pressure can be applied at different workouts.


The gold standard blood flow restriction training device is the Delphi Personal Tourniquet System from This device contains a Doppler ultrasound within the blood flow restriction cuff. This means we have the most accurate way possible to measure blood flow in the extremity and can precisely occlude the appropriate amount of flow. Safety features within the device include rapid shut offs, automatic times, and the Doppler are amazing features.

Most importantly for those in the medical community, the Delphi Blood Flow Restriction device is and FDA-listed device for BFR. The FDA defines full or partial vascular occlusion under “tourniquets” and is regulated that way. Thus, if a patient were to have a negative side effect during BFR training while using a Delphi unit, you can feel legally safe. Using other devices opens you up to litigation because a non-FDA approved device is being used to restrict blood flow.

So, What’s The Best?

There are two winners:

First, the Edge BFR Device is the clear best for athletes, strength coaches, and personal trainers. Its ability to measure pressure to accurately reproduce pressure between workouts is great. At a price tag of $99, it meets most people’s budgets as well.

For the rehab professional, the Delphi unit wins. This machine is fantastic, with doppler ultrasound and safety features built in. The FDA-approval also makes it the best option from a legal standpoint.

Smart Cuffs: How Blood Flow Restriction Training Is The Next Big Fitness Trend

From time to time, we’ll hear of “the latest innovation in fitness” that claims to change the way we’ll workout forever.

More often than not, these cutting-edge developments either never come to fruition, or don’t really catch on – even if they do make it to market.

BFR is said to be the next big thing in fitness to help build muscle faster and stronger in a shorter amount of time photocredit: Getty

However, there’s always one that’ll manage to prove itself and break through, and once it’s been identified as a game changer, will spread like wildfire among the boutique studios and more exclusive gyms before eventually making its way to the mainstream, sometimes even years after its debut.

Well, I have found what I believe to be one of those right here; a new, innovative way to workout that’s just on the verge of becoming the next big thing in fitness. It’s called Blood Flow Restriction training, or BFR.

While the theory is by no means new, and the idea behind it has been kicking around for some time, it’s only now that we are starting to see it become recognized by small studios – especially in the States – as a potentially accessible way to build muscle, faster and with better recovery time.

What exactly is BFR?

Also known as occlusion training, BFR training is essentially a strategy that involves the use of cuffs or wraps placed around a limb during exercise. The aim of this is to safely restrict venous blood flow from a working muscle while allowing arterial blood flow, which is usually done with low-intensity resistance training. Since the ability of that blood to escape is dramatically reduced, metabolic stress and cellular swelling are greatly increased. As a result, increased growth hormone, muscle hypertrophy, and muscle strength (are said) to occur.

If that doesn’t sound so clear in terms of how it works in a fitness studio, let me explain further, and eventually from a first-person perspective. I got to try out BFR in the form of Smart Cuffs at No1 Fitness in Tower Bridge, London along with Nick Kirk, a chiropractic sports physician who works internationally with the top performance practitioners in sports medicine, nutrition, psychology, and strength and conditioning.

I had a go using Smart Cuffs, one of few brands to bring BFR to the UK

Kirk told me that the reason BFR has been gaining traction now in the rehab and therapy world is that it allows us to achieve similar changes in strength and muscle growth without having to use higher loads.

“This obviously allows us to initiate training and rehabilitation earlier,” Kirk tells me.

“The benefits of BFR have long been known, however, it is only recently that professional therapists and trainers have been more widely implementing its use. It’s safe, effective and easily used when following the right protocols.”

The maker of Smart Cuffs, Smart Tools Plus, refers to BFR as “a game changer in the world of rehab”.

“Before now, it would take weeks, if not months, for post-surgical patients to begin rehab at 70-80% of their 1 rep max,” the company says. “However, the firm claims that BFR enables the patient to get those same results, but at 30-40% of their 1 rep max. Due to this, the patient can begin rehab much sooner, regain their strength to prevent atrophy, and ultimately get them back to functioning in a fraction of the traditional time.”

But, as Kirk mentions, BFR can be used safely in training as well as recovery*.

Why use BFR in training?

Because we are not loading close to our maximum capacity, we can theoretically accomplish similar benefits to heavy resistance training without the strain that lifting close to our maximum levels requires. Kirk explains that this means less strain on the joints and additionally, less time to achieve similar results.

“It acts as a bridge from early rehabilitation after, for example, an ACL surgery to returning to heavy lifting,” he adds. “It can also be used in aerobic training, with similar changes in muscle size and strength seen in shorter bouts of exercise when compared to exercising without the cuffs.”

I started using Smart Cuffs at the top of my arms. A 2kg dumbbell feels like 15kg

How does it feel?

I was somewhat apprehensive about how it would feel training with BFR, mainly because I didn’t know what to expect and with the words “blood restriction” in the name, I did worry it would be a little too intense. But actually, in a weird way, it rather pleasant. First off, the cuffs were placed on the uppermost portion of each limb (in this case, my arms) and my blood pressure was measured to ensure the straps were applied with the right amount of pressure to be safe. Once this was discerned, I was ready to work out.

Next, I was given very light weights, which felt a lot heavier than they were as I lifted them. This is because by restricting the veins and not the arteries, blood can keep pooling into the working muscle and stays trapped there, making it feel like a balloon filled with water to maximum capacity. By bringing all that blood to the muscles without letting it leave, two main things happen: firstly, you get a crazy pump as your muscles swell and feel super-sized due to the cellular swelling which shocks the muscles into growth, and secondly, it burns like hell. This is because your muscles quickly become oxygen deprived, creating a lot of metabolic stress – one of the three major mechanisms of muscle growth. As a result, using BFR during resistance training is said to not only increase strength but also boost muscle size, achieving the volume you’d expect from normal training of 12 weeks, in only four. Now you can probably understand why this technique is really taking off.

The Smart Cuffs also work on the lower limbs (legs) as shown above, and can be used while working out on a TRX system.

While I could feel a lot of tension in my muscle while lifting the weights, it didn’t hurt; it simply felt like my muscles had reached overload much more quickly, and with much lower weight than they would normally. You do feel a little like your muscles are going to pop towards the end of the set, but it’s a good feeling – almost like good old Arnie pumping some iron in a Gold’s Gym. The cuffs also work on the lower limbs (legs) as shown above, and can be used while working out on a TRX system.

The next big thing?

So now we know the potential benefits, what exactly makes it the next big thing in fitness? Well, there may also be systemic effects potentially from using BFR. Kirk explains:

“There are still unknowns about the effect of BFR on growth hormone circulation, but as work continues to be done on both athletic and ‘load compromised’ individuals (post surgery/injury).

“It might also have an effect on circulating hormone levels. There is some evidence that by inducing anaerobic or ischemic environments the body upregulates protein synthesis (muscle repair/growth), and so the use of BFR prior to intense exercise may also provide a protective effect, known as ischemic preconditioning – resulting in less damage during exercise and therefore a shorter recovery time. There may even be an analgesic effect which potentially is good for chronic pain or those trying to return to a more active life.”

He adds: “Obviously, it’s not a panacea, but it’s here to stay and is only going to become more and more prevalent in the rehab and performance world.”

Smart Cuffs has only just hit the UK, and I was told Tom Daley’s physio was one of the first to order it, so if that doesn’t speak volumes in how big this trend is going to get, I don’t know what does!

*Disclaimer: Please note, while Kirk mentions the potential benefits of BFR training, he adds that, as with any procedure or protocol that influences blood flow, it “should be done in the absence of any contraindications and under supervision of a trained professional”.

There are companies offering training to suitably qualified professionals, he says, including Owensrecoveryscience, which offers courses in the UK and Europe, and in the States.

Is Blood Flow Restriction Training Safe?

19 Jun Is Blood Flow Restriction Training Safe?

Posted at 18:00h in Exercises, Physical Therapy by zlongdpt

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Blood flow restriction training has emerged in the fitness and rehab worlds as the latest modality to help patients get their strength and muscle mass back faster than ever. A huge amount of research has shown that hypertrophy (muscle mass) gains can be achieved at very low loads (20-30% of an individual’s one-rep max) versus conventional training requiring loads at 75% or more.

This obliviously has HUGE implications in the rehabilitation world as it can help us get patients stronger without loading injured muscles, tendons, ligaments, and joints to the point where we further damage the tissues.

For the sports performance world, the ability to create muscle strength & hypertrophy at low loads, without the breakdown of muscle proteins, also makes it a possible addition to training programs.

I’ve reviewed this research previously in the following articles, but today, we’ll focus on the question of “Is Blood Flow Restriction Training Safe?” as there are several dangerous myths around the use of BFR.

The Science of BFR

Application of BFR

The Best BFR Devices

Does BFR Cause Blood Clots?

This is the first and most obvious concern with the implementation of BFR. Does placing a tourniquet and restricting blood flow increase-clotting risk?
Fortunately several studies have examined these questions and all support that BFR does not increase clot risk. In fact, both blood flow restriction training and heavy resistance training are associated with the release of several anti-coagulation factors (Jarrett 2004) and studies have shown no increases in clots when BFR training programs are implemented (Hylden 2014).

Is Blood Flow Restriction Safe on the Cardiovascular System?

This is the second concern with the use of BFR…are we potentially damaging the heart and / or blood vessels with BFR?

Let’s start with the incredibly amount of stress that heavy resistance training places on the body. During high intensity training, blood pressure values as high as 480/350mmHG during heavy lifting (80%1RM) and 255/190mmHG during simple bicep curls are seen (McDougal 1985)! And heart rates have been shown to reach 170BPM.

In contrast, while BFR training does increase both of these markers, research has shown blood pressure readings to only increase to 180/100mmHG and heart rate values to 110BPM (Takano 2005). Both considerably lower than that seen with heavy resistance training.

Other research has shown either no change or improvements in arterial compliance and stiffness with BFR (Kim 2009, Fahs 2011, Ozaki 2013, Ozaki 2011). Hunt (2013) found improvements of 14% in capillarity vs no changes in work matched controls.


The biggest risk factors come from a few variables: improper tourniquet width, too much tourniquet pressure, and improper placement of the tourniquet.

First up we’ll tackle tourniquet width, which has been improperly interpreted by many in the fitness world. BFR works through the partial occlusion of blood flow. According to multiple research studies, WIDER CUFFS DECREASE THE PRESSURE NEEDED TO RESTRICT BLOOD FLOW. This means that the small cuffs sold by many “BFR” manufacturers actually increase the risk of soft tissue damage. You MUST use a wider tourniquet to minimize this.

The next risk factor is too much pressure, which has already been partially covered. In the BFR certification courses I teach, we discuss LIMB OCCLUSION PRESSURE which is the MINIMAL amount of pressure needed by a specific patient, on a specific limb, on a specific day, needed to occlude the proper amount of blood flow.

Think of this as working hard for the same amount of money…you’d NEVER do that right? So we only want to use the MINIMAL amount of pressure necessary to make our strength & hypertrophy goals happen.

This is where the Delphi PTS system comes in for medical professionals, it takes care of almost all the safety concerns with BFR (and is the only device listed as approved by the FDA for use on patients – ALL OTHERS ARE SIGNIFICANT LEGAL LIABILITIES).

Finally, placement of the BFR device is incredibly important. There are only two places where a BFR device should be placed. That is the upper arm and upper thigh. This will minimize the risk on nerve damage. Placement of tourniquets in other areas has been known to cause nerve damage issues including nerve palsy’s such as drop foot.


There are several contraindications of BFR training that must also be observed for safe training. I won’t go through a full description of each (I suggest attending the ORS course for more on this) but be cautious and screen potential BFR users with the following conditions:


In summary, when performed CORRECTLY, blood flow restriction training seems to be as safe as conventional training. If you want to learn more about BFR rehab for the medical professional, visit

If you are a recreational athlete, read my article “The Best BFR Devices” for your options and download my BFR Training Guide.

Download the e-book that teaches you how to implement blood flow restriction training now!

Blood Flow Restriction Training

Original Editor – Vidya Acharya

Top Contributors – Vidya Acharya, Mandy Roscher, Tarina van der Stockt and Kim Jackson


Muscle weakness commonly occurs in a variety of conditions and pathologies. High load resistance training has been shown to be the most successful means in improving muscular strength and obtaining muscle hypertrophy. The problem that exists is that in certain populations that require muscle strengthening eg Chronic Pain Patients or post-operative patients, high load and high intensity exercises may not be clinically appropriate. Conditions that result in loss of muscle mass such as cancer, HIV/AIDS, diabetes and COPD could potentially benefit from muscle strengthening and muscle hypertrophy but cannot tolerate high intenstity/ loaded exercises. Blood Flow Restriction (BFR) training is a technique that combines low intensity exercise with blood flow occlusion that produces similar results to high intensity training. It has been used in the gym setting for some time but it is gaining popularity in clinical settings.

Blood Flow Restriction (BFR) Training

BFR training was initially developed in the 1960’s in Japan and known as KAATSU training. It involves the application of a pneumatic cuff (tourniquet) proximally to the muscle that is being trained. It can be applied to either the upper or lower limb. The cuff is then inflated to a specific pressure with the aim of obtaining partial arterial and complete venous occlusion. The patient is then asked to perform resistance exercises at a low intensity of 20-30% of 1 repetition max (1RM), with high repetitions per set (15-30) and short rest intervals between sets (30 seconds)

BFR and Strength Training

Understanding the Physiology of Muscle Hypertrophy.

Muscle hypertrophy is the increase in diameter of the muscle as well as an increase of the protein content within the fibres. An increase in cross-sectional area of the muscle directly correlates with an increase in strength.

Muscle tension and metabolic stress are the two primary factors responsible for muscle hypertrophy.

Mechanical Tension & Metabolic Stress

When a muscle is placed under mechanical stress, the concentration of anabolic hormone levels increase. The activation of myogenic stem cells and the elevated anabolic hormones result in protein metabolism and as such muscle hypertrophy can occur.

Release of hormones, hypoxia and cell swelling occur when a muscle is under metabolic stress. These factors are all part of the anabolism of muscle tissue.

Activation of myogenic stem cells

Myogenic stem cells, are found between the basal lamina and plasma membrane of myofibres. They are normally inactive and become activated in response to muscle injury or increased muscle tension. These cells are responsible for both repair of damaged muscle fibres and also the growth of the fibres themselves.

Release of hormones

Any exercise, resistance or aerobic, brings about a significant increase in growth hormone. Insulin-like growth factor and growth hormone are responsible for increased collagen synthesis after exercise and aids muscle recovery. Growth hormone itself does not directly cause muscle hypertrophy but it aids muscle recovery and thereby potentially facilitates the muscle strengthening process. The accumulation of lactate and hydrogen ions (eg in hypoxic training) further increases the release of growth hormone.

High intensity training has been shown to down regulate myostatin and thereby provide an environment for muscle hypertrophy to occur. Myostatin controls and inhibits cell growth in muscle tissue. It needs to be essentially shut down for muscle hypertrophy to occur.


Resistance training results in the compression of blood vessels within the muscles being trained. This causes an hypoxic environment due to a reduction in oxygen delivery to the muscle. As a result of the hypoxia hypoxia-inducible factor (HIF-1α) is activated. This leads to an increase in anaerobic lactic metabolism and the production of lactate.

Cell Swelling

When there is blood pooling and an accumulation of metabolites cell swelling occurs. This swelling within the cells causes an anabolic reaction and results in muscle hypertrophy. The cell swelling may actually cause mechanical tecnsion which will then activate the myogenic stem cells as discussed above.

Effects of Blood Flow Restriction on Muscle Strength

The aim of BFR training is to mimic the effects of high intensity exercise by recreating a hypoxic environment using a cuff. The cuff is placed proximally to the muscle being exercise and low intensity exercises can then be performed. Because the outflow of blood is limited using the cuff capillary blood that has a low oxygen content collects and there is an increase in protons and lactic acid. The same physiological adaptations to the muscle eg release of hormones, hypoxia and cell swelling, will take place during the BFR training and low intensity exercise as would occur with high intensity exercise.

Low intensity BFR training results in greater muscle circumference when compared with normal low intensity exercise. (1)

Low intensity BFR (LI-BFR) results in an increase in the water content of the muscle cells (cell swelling). It also speeds up the recruitment of fast-twitch muscle fibres. It is also hypothesised that once the cuff is removed a hyperemia (excess of blood in the blood vessels) will form and this will cause further cell swelling. 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

A study comparing (1) high intensity, (2) low intensity, (3) high and low intensity with BFR and (4) low intensity with BFR. While all 4 exercise reigmes produced increases in torque, muscle activations and muscle endurance over a 6 week period. The high intensity and BFR groups (1,3 and 4) produced the greatest effect size and were comparable to each other.


BFR Cuff

BFR requires a tourniquet to be placed on a limb. The cuff needs to be tightened to a specific pressure that occludes venous flow while still allowing arterial flow whilst exercises are being performed.

Simple pieces of equipment such as surgical tubing or elastic straps have been used in gym settings to achieve this result. These are not advisable as you are unable to monitor the amount of blood flow occlusion. A thin diameter may also cause too much local pressure and result in tissue damage.

BFR Cuff Width

A wide cuff is preferred in the correct application of BFR. 10-12cm cuffs are generally used. A wide cuff of 15cm may be best to allow for even restriction. Modern cuffs are shaped to fit the natural contour of the arm or thigh with a proximal to distal narrowing. There are also specific upper and lower limb cuffs that allow for better fitment.

BFR Cuff Material

BFR cuffs can be made from either elastic or nylon. The narrower cuffs are normally elastic and the wider nylon. With elastic cuffs there is an initial pressure even before the cuff is inflated and this results in a different ability to restrict blood flow as compared with nylon cuffs.

Elastic cuffs have been shown to provide a significantly greater arterial occlusion pressure as opposed to nylon cuffs.

BFR Cuff Pressure

Different blood flow restriction cuff pressure prescription methods:

  1. a standard pressure (used for all patients) for e.g. 180 mmHg;
  2. a pressure relative to the patient’s systolic blood pressure, for e.g. 1.2- or 1.5-fold greater than systolic blood pressure;
  3. a pressure relative to the patient’s thigh circumference.

It is the safest to use a pressure specific to each individual patient, because different pressures occlude the amount of blood flow for all individuals under the same conditions.

A Doppler ultrasound or plethysmography can be used to determine the blood flow to the limb. The cuff is inflated to a specific pressure where the arterial blood flow is completely occluded. This known as limb occlusion pressure (LOP) or arterial occlusion pressure (AOP). The cuff pressure is then calculated as a percentage of the LOP, normally between 40%-80%.

Using this method is preferable as it ensures patients are exercising at the correct pressure for them and the type of cuff being used. It is safer and makes sure that they are exercising at optimal pressures, not too high to cause tissue damage and also not too low to be ineffective.

The pressure of the cuff depends upon the width of the cuff as well as the size of the limb on which the cuff is applied.

The key to BFR is that the pressure needs to be high enough to occlude venous return and allow blood pooling but needs to be low enough to maintain the arterial inflow Perceived wrap tightness, on a scale of 0-10 has also been used to conduct BFR training. Wilson et al (2013) found that a perceived wrap tightness of 7 out of 10 resulted in total venous occlusion but still allowed arterial inflow.

Clinical Application

BFR has been used in athletes and recreational training to obtain muscle hypertrophy. It can also be used in clinical populations that cannot perform high intensity exercises because of the stage of their condition or pathology involved. . Examples of BFR training in the clinic:


Upper Limb: The tourniquet is placed on the upper arm. The cuff is inflated to resrict 50% of the arterial blood flow and 100% of the venous flow. Lower limb: The tourniquet is placed on the upper thigh. The cuff is inflated to restrict 80% of the arterial blood flow and 100% of the venous flow. With the cuff inflated to the correct pressure normal exercises are performed at about 20-30% of 1RM.

Exercise Prescription

1. Training Frequency

In theory, strength training with BFR can be done daily and in some studies, Nielsen et al suggest that it has been done twice a day. Several studies looking at Endurance training and BFR has shown effects with 4 – 6 days of training.

2. Training Duration

The effect’s size for training duration demonstrates that longer duration up to 10 weeks has the largest effect size. Early hypertrophy is observed with BFR and this may be from increased satellite fusion and resultant hypertrophy. It is common that the patient notices hypertrophy within the first 2 weeks of BFR training.

3. Rest Periods

The largest effect size is seen with rest periods of 30 seconds. It is important to keep the cuff inflated during the rest periods to capture the metabolites.

4. Tourniquet Cuff Pressure

The amount of pressure needed to occlude blood flow in the limb depends on the limb size, underlying soft tissue, cuff width and device used.

5. Limb Occlusion Pressure

It is the minimal amount of pressure needed to occlude arterial blood flow. 3rd Generation Tourniquet System features a built-in system to measure vascular flow, which allows personalised tourniquet pressure for each individual patient and eliminates the need to account for cuff width, limb size or blood pressure. A pressure of 80% occlusion for lower extremities and 50% for the upper extremities is recommended.

6. Training Intensity

A load of 15-30% 1RM has the largest size effect. A Higher load may have actually pumping effect to eliminate the metabolites and blunt the response. Lower intensities such as cycling, walking and isometrics have a lower response than 15-30% load.

7. Exercise Selection

BFR is typically a single joint exercise modality for strength training or low-level cardio exercise.

  • The standard repetition scheme used in BFR is a set of 30 repetitions followed by a 30-second rest followed by 3 more sets of 15 with 30 second rests in between (30/15/15/15). This gives us the target 75 repetitions. The first set of 30 can be seen as the priming load to begin the Cori cycle or the Lactic acid cycle. This first set is typically tolerated well by the patient and they often feel like it is too easy. The tourniquet is left inflated during the rest period, this is very important in order to trap metabolites.

  • The following 3 sets and rest periods will feel very difficult because of the subsequent lactate build up. The RPE is closely related to lactate accumulation. Also, the patients may feel their heart rate raise somewhat during the exercise. This is normal because of the reduced venous return, subsequent decreased stroke volume and increased HR to maintain cardiac output. If at anytime the patient becomes faint, dizzy has moderate to severe pain under the tourniquet cuff or begins to feel numbness or paresthesia in the limb stop the exercise session.
  • Once the patient finishes the exercise session the reperfusion of blood into the limb flushes out the lactate and the lactate “burn” in the limb generally goes away relatively quickly. They do often feel very fatigued in the limb and studies measuring force production immediately after BFR even at low loads have demonstrated significantly reduced force. Because of this high intensity exercises such as olympic lifts, plyometrics, agility work should not be done immediately after BFR. These same exercises should also not be done while using BFR. However, there will be times when the patient is unable to hit the target volume. Remember volume is key for strength and hypertrophy in BFR training.
  • Exercises:

Upper extremity: Upper body ergometer, isometrics, scapular rows, serratus punches, shoulder exercises, proprioceptive neuromuscular facilitation (PNF) patterns, bench press, push-up, elbow flexion, elbow extension, elbow supination, elbow pronation, wrist and all hand gripping exercises.

Lower extremity: Walking, cycling, isometrics, leg extension, hamstring curl, straight leg raises, terminal knee extension, hip range of motion exercises, leg press, squat, lunge, ankle and all Foot Exercises.

8. Exercise Progression

Below are guidelines to follow concerning exercise progression and difficulties with volume achievement: Load: 20-30% 1RM (Determined, Estimated). If the patient achieves:

75 Repetitions = Continue with training, re-assess 1RM within 1-3 sessions. Reestablish new 20-30% range as strength improves.

60-74 Repetitions = Continue with training, but extend rest period between sets 3 and 4 to 45 seconds. Until 75 repetitions is completed.

45-59 Repetitions = Continue with training, but extend rest period between all sets to 45- 60 seconds.

<44 Repetitions = Reduce the load by approximately 10% until 75 repetitions are achieved.

Forced to stop before 75 repetitions because of undue pain, soreness or general uncomfortable feeling underneath the tourniquet cuff = Reduce tourniquet pressure by 10mmHg at each training session until cuff tolerance is achieved. Ramp cuff pressure back up 10 mmHg to target limb occlusion pressure if patient can tolerate.

9. Rehabilitation Guidelines
  • Early phase rehab- prevent muscle atrophy and promote healing. BFR training would consist of low intensity isometrics with or without electrical stimulation, easy mat exercises or even no exercise with only BFR. Researchers in the UK are beginning a study using BFR in the ICU to decrease muscle atrophy.
  • Sub-acute stage- BFR can be used for slightly higher loads such as walking and cycling. This has been shown to increase strength, hypertrophy and endurance. As the patient can tolerate additional load, he can move into isotonic exercises with a 15-30% load. This will produce even more substantial gains.
  • Later phases of rehab- a typical transition to BFR and HIT training on alternating days can be made. This has demonstrated even larger gains than BFR alone. This also acts as a bridge for the patient to discharge to a home strengthening program consisting of just HIT training.
  • BFR can also be used as a form of strength and endurance training to supplement the patient while they are working on a higher-level program such as plyometrics, running and agility into the late phases of rehab.
  • In cases of setbacks due to reinjury, BFR is a great modality to start back up during these times to diminish the losses the patient might have during this setback. The patients really appreciate the fact that they are maintaining or increasing their strength while they are recovering instead of meds and RICE while they watch their gains atrophy daily.

Side Effects

Reported side effects while performing BFR exercises are fainting and dizziness, numbness, pain and discomfort, delayed onset muscle soreness.

All patients should be assessed for the risks and contraindications to tourniquet use before BFR application. Patients possibly at risk of adverse reactions are those with poor circulatory systems, obesity, diabetes, arterial calcification, sickle cell trait, severe hypertension, or renal compromise. Potential contraindications to consider are venous thromboembolism, peripheral vascular compromise, sickle cell anaemia, extremity infection, lymphadenectomy, cancer or tumor, extremity with dialysis access, acidosis, open fracture, increased intracranial pressure vascular grafts, or medications known to increase clotting risk.

Safety Implication

  1. Thrombus Formation

Although speculative, an initial safety concern regarding LL-BFR training included thrombus formation (i.e., blood clot). Research examining LL-BFR training with healthy individuals and older adults with heart disease found no change in blood markers for thrombin generation or intravascular clot formation. Furthermore, data from two surveys of nearly 13,000 individuals utilizing BFR training found that the incidence of deep venous thrombosis was <.06% and pulmonary embolism was <.01%. The systematic review to examine the safety along with short- and long-term effects of BFR exercise on blood hemostasis in healthy individuals and patients demonstrate that short-term BFR exercise does not exacerbate the activation of the coagulation system nor enhance fibrinolytic activity in young healthy subjects. The findings posit that BFR would be relatively safe for adults considered young and healthy, those who are middle-aged with stable ischemic heart disease, and older healthy adults. But the review also suggests the need to verify the effects of BFR exercise on hemostasis and its safety of BFR exercise on hemostasis as there is limited evidence available.

2. Muscle Damage

Data from the aforementioned surveys found the incidence of excessive muscle damage (i.e., rhabdomyolysis) to be <0.01%. The amount of muscle damage associated with BFR training is conflicting; however, a comparison between maximal eccentric actions and LL-BFR training to exhaustion in untrained individuals revealed comparable amounts of exercise-induced muscle damage. However, performing LL-BFR training to exhaustion in clinical populations is not recommended, therefore, it appears the risk of LL-BFR training resulting in excessive muscle damage is minimal. In general, it is well established that unaccustomed exercise results in muscle damage and delayed onset muscle soreness (DOMS), especially if the exercise involves a large amount of eccentric actions. DOMS is normal after unaccustomed exercise, including after LL-BFR training, and should subside within 24–72 hours.

3. Central Cardiac Responses

Research studies suggest that the cardiovascular system during exercise does not experience higher overload, which could be a risk factor for cardiac patients and physically inactive persons. This type of exercising could be considered safe.

4. Peripheral Vascular Changes

The effects of exercise on peripheral vascular changes are mixed. With ageing, the arterial compliance decreases and the resistance exercise may increase arterial stiffness in the elderly. Ozaki et al (Ozaki 2011) found significantly improved arterial compliance after 10 weeks of BFR walking in the elderly population. Clark et al (Clark 2011) found no change in arterial stiffness after 4 weeks of BFR training.

5. Tourniquets

By using the 3rd generation system the risk of tourniquet complication is very low, ranging from 0.04% to 0.8%. However, there is an inherent risk to tourniquet use. Some of the common complications are:

  • Nerve injury: Mechanical compression and neural ischemia play an important role. Nerve injury can range from mild transient loss of function to irreversible damage and paralysis.
  • Skin injury
  • Tourniquet pain
  • Chemical Burns
  • Respiratory, Cardiovascular, Cerebral circulatory and haematological effects caused by prolonged ischaemia
  • Temperature changes

BFR training can be viewed as an emerging clinical modality to achieve physiological adaptations for individuals who cannot safely tolerate high muscular tension exercise or those who cannot produce volitional muscle activity. However, continued research is needed to establish parameters for safe application prior to widespread clinical adoption.

Additional Resources

  1. Hamilton, David & MacKenzie, Matthew & Baar, Keith. (2009). Molecular mechanisms of skeletal muscle hypertrophy Using molecular biology to understand muscle growth. Accessed from
  2. 2.0 2.1 2.2 2.3 VanWye WR, Weatherholt AM, Mikesky AE. Blood flow restriction training: Implementation into clinical practice. International journal of exercise science. 2017;10(5):649.
  3. Loenneke JP, Fahs CA, Rossow LM, Sherk VD, Thiebaud RS, Abe T, Bemben DA, Bemben MG. Effects of cuff width on arterial occlusion: implications for blood flow restricted exercise. European journal of applied physiology. 2012 Aug 1;112(8):2903-12.
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  6. 6.0 6.1 Bonnieu A, Carnac G, Vernus B. Myostatin in the pathophysiology of skeletal muscle. Current genomics. 2007 Nov 1;8(7):415-22.
  7. 7.0 7.1 Luke O’Brien. Blood Flow Restriction Therapy Course. Physioplus. 2019
  8. 8.0 8.1 8.2 8.3 8.4 8.5 Johnny Owens. Owens Recovery Science. Blood Flow Restriction Rehabilitation Accessed from
  9. 9.0 9.1 de Freitas MC, Gerosa-Neto J, Zanchi NE, Lira FS, Rossi FE. Role of metabolic stress for enhancing muscle adaptations: practical applications. World journal of methodology. 2017 Jun 26;7(2):46.
  10. Wideman L, Weltman JY, Hartman ML, Veldhuis JD, Weltman A. Growth hormone release during acute and chronic aerobic and resistance exercise. Sports medicine. 2002 Dec 1;32(15):987-1004.
  11. 11.0 11.1 11.2 Wilson JM, Lowery RP, Joy JM, Loenneke JP, Naimo MA. Practical blood flow restriction training increases acute determinants of hypertrophy without increasing indices of muscle damage. The Journal of Strength & Conditioning Research. 2013 Nov 1;27(11):3068-75.
  12. 12.0 12.1 Spranger MD, Krishnan AC, Levy PD, O’Leary DS, Smith SA. Blood flow restriction training and the exercise pressor reflex: a call for concern. American Journal of Physiology-Heart and Circulatory Physiology. 2015 Sep 4;309(9):H1440-52.
  13. Sousa, Jbc et al. “Effects of strength training with blood flow restriction on torque, muscle activation and local muscular endurance in healthy subjects.” Biology of sport vol. 34,1 (2016): 83-90. doi:10.5114/biolsport.2017.63738
  14. McEwen JA, Owens JG, Jeyasurya J. Why is it Crucial to Use Personalized Occlusion Pressures in Blood Flow Restriction (BFR) Rehabilitation?. Journal of Medical and Biological Engineering. 2019 Apr 2;39(2):173-7.
  15. 15.0 15.1 15.2 15.3 Bond CW, Hackney KJ, Brown SL, Noonan BC. Blood Flow Restriction Resistance Exercise as a Rehabilitation Modality Following Orthopaedic Surgery: A Review of Venous Thromboembolism Risk. journal of orthopaedic & sports physical therapy. 2019 Jan;49(1):17-27.
  16. Loenneke JP, Fahs CA, Rossow LM, Thiebaud RS, Mattocks KT, Abe T, Bemben MG. Blood flow restriction pressure recommendations: a tale of two cuffs. Frontiers in physiology. 2013 Sep 10;4:249
  17. Buckner SL, Dankel SJ, Counts BR, Jessee MB, Mouser JG, Mattocks KT, Laurentino GC, Abe T, Loenneke JP. Influence of cuff material on blood flow restriction stimulus in the upper body. The Journal of Physiological Sciences. 2017 Jan 1;67(1):207-15.
  18. Loenneke JP, Kim D, Fahs CA, Thiebaud RS, Abe T, Larson RD, Bemben DA, Bemben MG. Effects of exercise with and without different degrees of blood flow restriction on torque and muscle activation. Muscle & nerve. 2015 May;51(5):713-21.
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  26. DePhillipo NN, Kennedy MI, Aman ZS, Bernhardson AS, O’Brien L, LaPrade RF. Blood Flow Restriction Therapy After Knee Surgery: Indications, Safety Considerations, and Postoperative Protocol. Arthroscopy techniques. 2018 Oct 1;7(10):e1037-43.
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What You Should Know About Blood Flow Restriction Rehabilitation

Blood Flow Restriction (BFR) is a hot topic in physical therapy right now. Even though it has been around since the 1960s, there has recently been a surge in BFR research that supports how this technique can improve patient outcomes.

History of BFR

In 1966, 18-year-old Yoshiaki Sato had an epiphany after standing up from a “seiza” position at a funeral – his legs felt as if they had been through a fatiguing workout. After a catastrophic ankle injury skiing in 1973, he was in a long leg cast for six weeks. During his immobilization, Sato initiated the first “blood flow restriction training” by using belts and performing isometric exercises. Doctors were shocked when his leg was not atrophied or tender when the cast was removed. Throughout the 1970s, Sato investigated restriction training on himself and other Japanese body builders. During the 1980s, Sato started his own personal training clinic, introducing “occlusion training,” quickly catching on with European body builders as well. In the 1990s, Sato started doing formal research and developed “KAATSU” pneumatic bands. “Ka” means “additional” and “Atsu” means “pressure.” Use of Sato’s formal KAATSU equipment requires formal apprenticeship in Japan, so many Westerners have made use of various wraps, straps, bands, belts, blood pressure cuffs and surgical tourniquets in attempt to replicate Dr. Sato’s results.

BFR rehabilitation has gained more wide-spread popularity as it started being used for military personnel who were struggling to improve muscle strength and size in their injured limbs after blast injuries, amputations and limb salvage procedures. When attempting to lift heavy weights, they were significantly limited due to pain and weakness. With the help of BFR training, they were able to achieve their strengthening goals using lighter weights. Olympic athletes have since caught on to BFR taking workouts to the point of fatigue without the heavy lifting. Now BFR is becoming more popular in outpatient physical therapy as well, as it can help minimize the effects of limited extremity use.

What is BFR?

During BFR training, a patient or athlete works out with a narrow, elastic band around the upper portions of the exercising arm or leg. This band partially restricts venous blood flow but does not affect arterial inflow to the extremity. Doing this produces a systemic response comparative to heavy weight training. Performing high repetitions of a particular exercise while wearing the elastic band and using light weights will allow the patient to receive the strengthening benefits of heavy lifting without the stress to tissues that may be healing from a recent injury or surgery.

How Does This Work?

In a nutshell, exercising with lighter weights while using blood flow restriction causes a local disturbance of homeostasis, as the working muscle does not receive enough blood flow to sustain contractions. This creates a release of autonomic and anabolic hormones that move throughout the body. This systemic response augments the local response, causing increased protein synthesis. Because little damage is done to the soft tissue by avoiding heavy weight lifting, improvements in strength and endurance can come quickly. All tissues both proximal and distal to the blood flow restriction bands can benefit from these effects.

Who Benefits from BFR?

BFR training can be performed in a regular fitness routine, but can also be safely performed under the supervision of trained professionals in outpatient physical therapy clinics. BFR can safely be used on patients in the acute phase of rehabilitation following most upper or lower extremity surgeries, including ACL reconstruction, meniscectomy, hip/knee replacement, rotator cuff repair or any tendon repair. Research has shown BFR can minimize loss of muscle mass and decrease bony healing time during the early immobilization phases, allowing patients to improve both muscle size and strength without the stress of heavy lifting on healing soft tissue. Patients with osteoarthritis, rheumatoid arthritis, osteopenia or osteoporosis may also benefit from BFR. Additionally, BFR has been utilized after strokes or spinal cord injuries and with athletes who want to improve performance.

Is BFR Safe?

Research has shown that BFR is not only comfortable for the patient, but also safe and effective when exercises are performed appropriately and when equipment is monitored by a trained blood flow restriction professional. This service is now available to be performed by trained clinicians at select Athletico clinics. If you are interested in learning more about BFR, click the button below to request an appointment.

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The Athletico blog is an educational resource written by Athletico employees. Athletico bloggers are licensed professionals who abide by the code of ethics outlined by their respective professional associations. The content published in blog posts represents the opinion of the individual author based on their expertise and experience. The content provided in this blog is for informational purposes only, does not constitute medical advice and should not be relied on for making personal health decisions.

Blood flow restriction training

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