When you’re recovering from injury or surgery, it’s common to experience muscle atrophy (wasting) and associated weakness. Both these two factors pose significant hurdles to returning to your pre-injury condition and function as soon as possible. Part of our role as physiotherapists in the early stage of injury or post-surgical recovery is work to address these through targeted and tailored rehabilitation to improve strength and achieve muscle growth. We know that the best way to do this is through high load (weight) resistance training, usually at greater than 70% of our 1 rep maximum (the most weight we can lift only once!).
What problem does blood flow restricted training help to solve?
The issue with certain conditions or population groups who require muscle strengthening is that not all are suited to lifting heavy weights (post-operative, elderly, people with other health conditions etc.). This is one of the benefits of blood flow restriction training – it allows us to combine lighter, less intense weights or exercises with blood flow restriction to achieve similar results to higher weight, more intense exercise.
How does it work?
By placing a cuff around the limb, we reduce the ability for blood to be pumped back to the heart from that limb. Basically, we’re Increasing the demand for oxygen within that muscle, making the muscle work harder to contract than it would otherwise. In doing so, the body releases hormones, cells within the muscle start to swell and we get the production of lactic acid amongst other things like we would as if we were lifting heavy weights! Basically, blood flow restriction training causes muscle stress at weights that wouldn’t normally allow us to do so. Make sense?!
What does science tell us?
It’s REALLY effective…
- Low intensity blood flow restricted training results in greater muscle growth when compared with normal low intensity exercise. (Hamilton et al. 2009)
- Blood flow restricted training speeds up the recruitment of fast-twitch muscle fibres, fibres that are difficult to recruit without heavy loads. (Spranger et al. 2015)
- Short lived, low intensity blood flow restricted training for approximately 4-6 weeks has been shown to cause a 10-20% increase in muscle strength. (Spranger et al. 2015)
One particular research paper from 2016 compared the following:
- High intensity strength training
- Low intensity strength training
- High and low intensity strength training with the addition of blood flow restriction via a cuff
- Low intensity strength training with the addition of blood flow restriction via a cuff
The results? While all 4 strength training regimes produced increases in torque, muscle activations and muscle endurance over a 6 week period – the high intensity (group 1) and BFR (groups 3 and 4) produced the most significant improvements, all of which were comparable to each other.
Is it safe?
In short, when performed safely and with the correct technique, the answer to this question is yes.
Thorough screening should be performed to ensure you’re the right candidate to undertake BFR training.
There are three concerns that have been examined in reference to the safety of BFR.
- Firstly, could placing a tourniquet around a limb and restricting someone’s blood flow increase clotting risk?
Studies have shown no increases in clots when BFR training programs are implemented (Hylden 2014) Interestingly, both blood flow restriction training and heavy resistance training are associated with the release of several anti-clotting factors (Jarrett 2004).
2. Are we unnecessarily stressing the heart and blood vessels with BFR?
We are stressing the cardiovascular system, yes, but much less than when lifting heavy weights, where blood pressure values reach as high as 480/350mmHG.
While BFR training also increases blood pressure, research has shown blood pressure readings to only increase to 180/100mmHG, considerably lower than that seen with heavy weight training.
3. Are we damaging the muscle?
BFR absolutely stresses the muscle in order to achieve the benefits we’re going for. However, like normal resistance training delayed onset muscle soreness should resolve within 2-3 days at a maximum.’
It’s just another tool in our tool belt, and something we’ll continue to keep up to date with over the next few years. Ultimately, we think the research is too good to ignore! For individuals without any health conditions where they’ve been thoroughly screened, BFR can be used as a bridge to heavier lifting for individuals that are capable of lifting heavier loads. We see this being particularly useful in the post-operative population for minimising atrophy and improving strength quicker than we could potentially otherwise.
Hamilton, David & MacKenzie, Matthew & Baar, Keith. (2009). Molecular mechanisms of skeletal muscle hypertrophy Using molecular biology to understand muscle growth. Accessed fromhttps://www.researchgate.net/publication/235702201_Using_molecular_biology_to_understand_muscle_growth/stats
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.
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
VanWye WR, Weatherholt AM, Mikesky AE. Blood flow restriction training: Implementation into clinical practice. International journal of exercise science. 2017;10(5):649.