5 Myths About Blood Flow Restriction Training

To continue this series on BFR (see Part 1 and Part 2), I will highlight some of the most common questions that I receive from clinicians and my answers.

Certifications exist because a patented device or technique is being utilized or taught. A great example of this is the Graston technique and its associated tools. I get why they would do this from a business standpoint.

But the idea that all clinicians must get a certification in instrument assisted soft tissue manipulation (IASTM) because one company created a certification program to educate clinicians about their specific technique and how to correctly use their tools is absurd.

There is no difference with blood flow restriction training. Given the proper training that is backed by science and focuses on safety and efficacy, any clinician who wants to deploy the principles of BFR should be able to as long as it is covered by their insurance policy and state practice acts.

This is by far the biggest bone of contention with the discussion surrounding BFR. Understanding the definitions of listed, cleared, approved, and 510(k) exempt by the FDA for medical devices, and how they apply to the category which BFR bands fall under, helps bring clarity to this statement. 

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Listing a device is the most basic task required of the manufacturers or distributors of a medical product. Listing is not stringent at all. Essentially, it means that as long as the device meets pre-existing standards for the category which have already been identified as safe, the device is automatically “approved” by the FDA.

There is no extra safety or effectiveness process involved with listing a device. Cleared devices are those new devices identified by the FDA as being “substantially equivalent to another legally marketed device."

They must go through the 510(k) submission process, which requires a manufacturer to notify the FDA of their intent to market at least 90 days in advance. This allows the FDA to determine whether the new device is “equivalent to a device already placed into one of the three classification categories.”

Lastly, approved devices are defined by the FDA as needing a “premarket approval (PMA) prior to marketing” and are generally reserved for high risk devices. Therefore, they must provide “reasonable assurance of the device’s safety and effectiveness” during the initial process.

You can search for cleared and approved devices utilizing the 510(k) Premarket Notification database. Blood Flow restriction devices, regardless of the complexity of the design, are considered by the FDA to be pneumatic tourniquets.

The FDA lists pneumatic tourniquets under the “General and Plastic Surgery Device” category, with all devices under this heading considered “Therapeutic Devices” (see FDA Code of Federal Regulation 878.5910 here)

The FDA defines a pneumatic tourniquet as an “air-powered device consisting of a pressure-regulating unit, connecting tubing, and an inflatable cuff. The cuff is intended to be wrapped around a patient’s limb and inflated to reduce or totally occlude circulation during surgery.” (NOTE: emphasis of underlining is my own). Sounds like a BFR device to me!

In addition, pneumatic tourniquets are classified by the FDA as Class I (general controls) devices. Therefore, the device is exempt from the 510(k) premarket notification procedures discussed above. This means that the device does NOT need FDA review prior to marketing devices.

This is because they are considered low risk by the FDA and therefore, do not need to provide “reasonable assurance of safety and effectiveness.” Thus, they only need to be listed with the FDA. It is disingenuous and spreading a false narrative to say anything else.

In fact, as it currently sits right now, any BFR device that is listed with the FDA and not used during general surgery as the definition of pneumatic tourniquet states, is technically being used off-label. This isn't the devil though as healthcare practitioners can utilize devices off-label with proper safeguards if they feel the patient will benefit.

But being considered 510(k) exempt does not mean it is the wild west. Pneumatic tourniquets aimed for medical use are subject to limitations in FDA Code of Federal Regulation 878.9 (see here), which is a good thing!

• be suitable for their intended use
• be adequately packaged and properly labeled

• have establishment registration and device listing forms on file with FDA (my note here: if they plan on marketing as medical device)
• be manufactured under a quality system (with the exception of a small number of class I devices that are subject only to complaint files and general recordkeeping requirements)

What this means is that as long as a device is not intended for a use different from the “intended use of a legally marketed device in that generic type of device” OR  is not "modified to operate using a different fundamental scientific technology," it does not need pre-market approval and therefore cannot be considered cleared or approved by the FDA.

Yet, let me be very clear: just like anything else, the onus comes back on the clinician to choose the device they are comfortable with and to deploy proper safeguards like Doppler ultrasound (the industry gold standard for identifying limb occlusion pressure or LOP) and confer with their state practice acts and insurance policy coverage.

If you search the 510(k) premarket notification database for approved and cleared devices, there are not any FDA approved or cleared devices for blood flow restriction and certainly not for the clinical rehabilitation population.

Any BFR device that uses the term "FDA approved" is really only LISTED with the FDA because the category of pneumatic tourniquets, which BFR devices fall under, is 510(k) exempt. Just because this category is exempt does not mean general controls are not or should not be present.

Given the ease in listing a device under this category, I suspect it is only a matter of time before we see more devices being listed as pneumatic tourniquets.

The research for the use of blood flow restriction (BFR) training in clinical populations is expanding by the day. And it is very promising! Overall, the literature indicates that while there are some definite contraindications, BFR is safe for use with a wide variety of clients, including post-op, osteoarthritis, and deconditioned patients.

From a post-surgical perspective, during periods of non-weight bearing, BFR has been shown to be highly effective at reducing atrophy and loss of strength and muscle mass which could help quicken the transition to full weight-bearing status assuming the post-op protocol allows it.

What I would like to clarify is that while BFR is deemed safe in clinical populations, proper safeguards must be taken, including the use of Doppler Ultrasound to find the limb occlusion pressure (LOP). This will help dramatically reduce the potential risks associated with BFR use, improve patient compliance, and enhance outcomes.

In addition, the intensity at which you utilize BFR between athlete and clinical populations will be different. Clinical populations may add minimal resistance to exercises depending on their phase of rehabilitation, but nothing compared to athletes. See Myth #5 for an expansion on this topic.

This is absolutely, 100% false! The goal of BFR is to create an optimal anabolic environment, without inducing muscle breakdown as seen with traditional strength training. Higher pressures do not correlate in the research to higher or quicker physiological adaptations - in fact, there is an increased risk with minimal benefit at higher pressure.

Therefore, whenever you are in doubt or the client/patient cannot tolerate high pressure, it is more about the consistency of use and time under this anabolic environment that produces results.Think of this as anything else that we prescribe - what is the minimum effective dose (MED)?

Furthermore, a higher pressure increases the risk for injury. Because veins are more superficial than arteries and nerves, a moderate pressure with BFR will restrict venous return but not affect arterial or nerve function.

The same pressure on everyone creates a different stimulus. It may produce the same muscular adaptations but cardiovascular response may be different. BFR pressure should be set individually, where at the very least, the subject’s limb circumference, arterial blood pressures, and cuff design (width and shape) are to be taken into the account.

Doppler US is the gold standard to identify limb occlusion pressure, which factors in the aforementioned items.

Principle: Kiss it simple, stupid! As stated above, if we know the goal of BFR is create an optimal anabolic environment through disturbance of homeostasis, while limiting muscle breakdown, this is a perfect example of where “less is more."

When I utilize BFR with my patients, I tend to utilize the non-sexy exercises which we have all grown to hate because they don’t seem to be effective in the clinic - SLR, bridges, TKE, calf raises, bodyweight squats/lunges. But low intensity resistance exercises (LIRE) are not higher enough in intensity to be effective at inducing physiological adaptations.

Remember, we are looking to get a systemic response so adding extra weight or more complex exercises doesn’t increase the response. But with BFR, these "basic" exercises become more effective. Higher reps and sets is the name of the game!

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