The Safety of BFR
In the last blog about BFR, I discussed what BFR is and how it works. In this post, let’s chat about the safety of BFR as there are a bunch of myths out there that need to be dispelled.
Like any other intervention we utilize as clinicians, whether it is an actual tool or a technique - blood flow restriction (training) is NOT for everyone. However, when BFR is used with the proper precautions and safety measures, and by trained and experienced clinicians, it is highly effective at augmenting the physiological adaptations to strength training in populations regardless of age or training status. This is even true in clinical and rehabilitation populations!
As with most things in life, we cannot say that there is no risk at all. A study done by Nakajima, et al. in 2006 found that out of 12,642 patients undergoing BFR, the incidence of side effects was as follows: venous thrombus (0.055%), pulmonary embolism (0.008%) and rhabdomyolysis (0.008%). Clearly, a risk is present but much lower than most people think.
Interestingly, there is also no evidence (admittedly, the literature is limited in number on this) that there is any negative CV or vascular response such as damage to vessel tissue. In fact, there are many studies that have shown improved blood flow post-exercise and increased angiogenesis (new blood vessel formation). This may help explain the reduction in systolic and diastolic pressures that is seen in some individuals after the use of BFR. (Cezar, et al. 2016)
The most common reported side effects from user of BFR are typically delayed onset muscle soreness (DOMS), numbness, dizziness, and bruising. Yet, these responses do not typically last long and can be minimized with proper monitoring and application by a clinician.
What should I monitor?
When utilizing BFR, it is important for clinicians to monitor the responses prior to and after use. Luckily, this is much easier than people think!
There are some general signs and symptoms that typically occur with too high of pressure. Higher pressures do not correlate in the research to higher physiological adaptations - in fact, there is an increased risk with minimal benefit at higher pressure (remember, veins are superficial compared to arteries). 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.
If these are reported by the patient, discontinue BFR and check location and pressure of the band before continuing use:
- Sensation of numbness
- Pins and needles
- Uncomfortable tingling
- Severe discomfort
- Lightheadness or dizziness
Clinicians can also ask patient or clients to rate their perception of the tightness of the cuff on a scale of 0-10. Along this isn’t enough to determine effectiveness, but it does help modify the treatment as needed (similar to RPE). 7/10 perceived tightness has been shown in the literature to be linked to most effectiveness.
How can I avoid potential problems?
Most importantly, a thorough patient history and examination before use will help identify absolute contraindications to BFR. These include history of DVT, Stage III or greater hypertension, higher class arrhythmias, early post-operative period (few days), and acute sickness or fever.
There are also some relative contraindications to be aware of; the more co-morbidities someone has, the more likely that BFR is contraindicated. These include (list is not all-inclusive): pregnancy, Stage II hypertension or lower, BMI > 30 kg/m2, malignancy, and atrial fibrillation.
Location of the BFR band is important as well. For the upper extremity, the band should be placed proximal to the biceps muscle belly, just under the deltoid tuberosity. For the lower extremity, it should be placed as proximal on the thigh near the gluteal fold as possible.
These are the ONLY places that the cuff should be placed. Some have advocated for the use at the forearms or calf but the arteries and nerves are more superficial in this area which substantially increases the risk of injury. I shouldn’t have to say this but...under no circumstances should belts be placed around the neck!
Why Doppler US is Critical for Safety in Clinical Rehab Populations
In addition, as an objective measure, I strongly advocate for the use of Doppler Ultrasound when using BFR in the clinical and rehabilitation populations. Doppler Ultrasound allows the clinician to individualize the pressures for each client or patient by finding their limb occlusion pressure (LOP). Limb occlusion pressure is minimum amount of pressure that occludes blood flow to the limb. Remember, we want to restrict blood flow, not occlude it! The LOP also takes into account the patient’s limb and vessel characteristics as well as the type of cuff that is being utilized.
Therefore, every time a patient comes in and I am going to use BFR, I retake their LOP for that day or limb. Hydration and other factors can slightly alter LOP so it’s best to recheck and monitor. At the very least, make sure to check for arterial blood flow using manual palpation of the radial or brachial artery in the upper extremity, and the dorsalis pedis or posterior tibial artery in the lower extremity.
Check out this video I made that describes the use of Doppler US with BFR!
Conclusion
BFR is safe and effective for a variety of clinical and rehabilitation populations. Proper safety measures help ensure appropriate use. Utilize Doppler US to find limb occlusion pressure to individualize pressures and be aware of relative and absolute contraindications.
Make sure to check out the Modern Strength Training: Blood Flow Restriction live seminar being held August 5-6, 2017 - register here!
Feel free to contact me with any questions!
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References
- Cezar MA, et al. Effects of exercise training with blood flow restriction on blood pressure in medicated hypertensive patients. Motriz. 2016. 22(2): 9-17.
- Nakajima T, et al. Use and safety of KAATSU training: Results of a national survey. International Journal of Kaatsu Training Research. 2006. 2: 5-13.
- Heitkamp, HC, et al. Training with blood flow restriction mechanisms, gain in strength and safety. The Journal of Sports Medicine and Physical Fitness. 2015; 55(5), 9–15.
- Nakajima T. Key Considerations when conducting KAATSU training. Int. J. KAATSU Training Res. 2011; 7: 1-6.
- Loenneke JP, et al. Potential Safety Issues with blood flow restriction training. Scand J Med Sci Sports. 2011; 21(4): 510-518.
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