One of the hardest challenges when recovering from an injury, surgery, or while in constant pain is the ability to maintain strength and avoid muscle atrophy (muscle loss). Any one of these situations can limit our ability to train due to the risk of causing further injury, or simply because normal training hurts too much. The solution is blood flow restriction (BFR) training. This form of training has gained a lot of popularity in recent years, and the research surrounding it continues to show major benefits. If you’re worried that your injury is going to hold you back or undo all of your hard work then keep reading because this might be a valuable solution for you.
So you are probably asking yourself what exactly is BFR, how does it work, and is it safe to use? All fair questions, and especially the last one given that the name suggests that we are going to be restricting blood flow. This might sound a little frightening on the surface, but let me dive in a little deeper.
Building Muscle and Strength
Let’s start with a little bit of background on building muscle and strength. Current and past research has shown time and time again that higher training loads are required in order to achieve meaningful muscle hypertrophy and increases in strength. The American College of Sports Medicine has provided guidelines for strength and hypertrophy training and recommends loads ranging from 60% to 100% of our 1 repetition maximum (1RM) depending on experience level.5 The table below gives some very general guidelines on training loads based on different training goals.
What is Blood Flow Restriction Training?
BFR training provides an alternative way to maintain muscle mass and strength while our body recovers from an injury
This is obviously very problematic if you are in a lot of pain or have an injury that doesn’t allow heavier loads without the risk of further injury. This is where BFR training comes in and provides an alternative way to maintain muscle mass and strength while our body recovers.
Research has shown that low-load resistance training with BFR at between 20-40% of our 1RM can produce similar hypertrophy effects and strength gains as high load resistance training, and oddly enough BFR showed less muscle and strength loss after surgery or immobilization without any exercise at all.1,3
As you can see in the table above under normal circumstances training with loads this low would normally improve muscular endurance, but not with BFR. Now some of this sounds too good to be true and to no surprise, high load resistance training still comes out on top. However, this is one way we can ensure that all of your hard work isn’t just thrown away after an injury.
What does BFR look like?
So what does BFR look like? Well it involves the use of an inflatable cuff around your arm or leg which restricts, but does not fully prevent blood flow to the arm or leg.1 So as you can see it’s not quite as terrifying as it sounds as we are only limiting the amount of blood flow reaching the muscles, not cutting it off completely. I would compare it to the feeling of wearing a blood pressure cuff at a doctors appointment, but not quite as snug.
Here’s what it looks like:
Why use BFR Training?
The reason we are doing this is to create a hypoxic (lacking in oxygen) environment in the muscles as it is believed that this achieves increased metabolic stress and mechanical tension when paired with exercise to create an optimal environment for muscle growth.1
Is it safe for everyone to use?
So all of this sounds great, but is it safe for everyone to use? Generally speaking yes, BFR training is safe to use in just about everyone. There are, of course, some exceptions and some concerns that have been raised with the growing popularity of this form of training so let’s get into them.
The common concerns brought up with BFR training include:
- Blood clots
- Excessive muscle damage
- Nerve damage
- Abnormal exercise pressure reflex.4
Research focused on low load BFR training has shown little to no risk of blood clot formation in healthy adults, older adults with cardiovascular disease, and post operative individuals.4 Surveys of individuals using BFR have reported extremely low rates of blood clots in less than 0.06% of those surveyed.2,4 Similar results were found for muscle damage with rates of less than 0.01% reported for excessive muscle damage resulting in rhabdomyolysis4, but delayed onset muscle soreness was common in untrained individuals as is expected with any form of unaccustomed exercise. While adverse effects are rare, caution should be used for individuals with heart failure, high blood pressure, or peripheral artery disease. Appropriate screening, monitoring, and conservative cuff pressures should be used if considering BFR training for these individuals.4
Some other potential side effects of BFR training include temporary numbness and delayed onset muscle soreness (DOMS), but we can address this by reducing cuff pressure and reducing training load, especially for those who are new to BFR or new to resistance training.
Some of the parameters for BFR are still in the early stages in the research, but here are some general guidelines and principles for anyone out there interested in using BFR on their own or with clients:1,2,4
- Less is more – most beneficial when used 2-3 times per week
- High volume is ideal – standard protocols include 75 repetitions over 4 sets (i.e. 30/15/15/15) with 30 second break intervals
- 20% of 1RM minimum
- Early hypertrophy in less than 4 weeks is common! – hypertrophy often occurs before strength gains which is the reverse of what we see in regular resistance training
- Cuff pressures between 40-90% of arterial occlusion pressure are the most common application- feel for loss of distal pulse (i.e. wrist, ankle) to estimate arterial occlusion pressure
- Wider cuffs are safer and require less cuff pressure
So in summary, BFR training is quite safe to use and with appropriate screening the chance of adverse events is extremely low. It provides an alternative training method both in everyday training and in rehabilitation settings where higher training loads are unsafe or inaccessible.
If this describes your current situation and you’re looking for physiotherapy tailor-made to your current needs and goals, check out Pivotal’s High Performance Centre and give blood flow restriction training a try!
Byron Turba, MScPT
Physiotherapist at Pivotal Physiotherapy
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1McEwan, J.A., Owens, J.G., & Jeyasurya, J. (2019). Why is it crucial to use personalized occlusion pressures in blood flow restriction (BFR) rehabilitation? Journal of Medical and Biological Engineering, 39, 173-177.
2DePhillipo, N.N., Kennedy, M.I., Aman, Z.S., Bernhardson, A.S., O’brien, L., & LaPrade, R.F. (2018). Blood flow restriction therapy after knee surgery: indications, safety considerations, and postoperative protocol. Arthroscopy Techniques, 7(10), 1037-1043.
3Hughes, L., Paton, B., Rosenblatt, B., Gissane, C., & Patterson, S.D. (2017). Blood flow restriction training in clinical musculoskeletal rehabilitation: a systematic review and meta-analysis. British Journal of Sports Medicine, 0, 1-11.
4Vanwye, W.R., Weatherholt, A.M., & Mikesky, A.E. (2017). Blood flow restriction training: implementation into clinical practice. International Journal of Exercise Science, 10(5), 649-655.
5ACSM. (2009). American College of Sports Medicine position stand. Progression models in resistance training for healthy adults. Medicine and Science in Sports and Exercise, 41, 687–708.