What is it?
Occlusion training is one of the newest and most touted training methods presently for building muscle, but what exactly is it? The technical term for occlusion training is Blood Flow Restriction (BFR). Simply, it involves medical tourniquets or knee/elbow wraps to restrict the level of blood flow to the working muscles. It is a type of exercise that is undertaken at low intensities that can elicit the same results as high intensity exercise. The aim is to restrict the blood via venous return, but not the delivery of new blood via the arteries. This then leads to a build up of fluid and lactic acid in the working muscles. At this point many of you reading this that have not come across BFR before would be right in thinking that this sounds a little counter intuitive, and conflicts with the standard way for hypertrophy training, which partly focuses on driving as much blood to the muscles as possible. So how exactly does occlusion training help to build muscle if it seems so at odds with current methods?
How it works
There are many mechanisms with how this stimulates muscle growth. The aim of BFR is to ‘moderately’ restrict the flow blood into the muscle by prevent blood from leaving the muscle via the veins, but whilst still allowing blood and nutrient delivery in through the arteries. As stated earlier, this leads to a pooling of fluid and lactic acid in the working muscles. This leaves the muscle cells two options, burst or grow, and so it is forced to do the latter. The swelling and expanding of cell membranes has been theorized to create more room for the muscle cells to growth into.
This pooling of blood and fluid also leads to a build up of lactic acid and other metabolites in the muscle cells. This is very important as it leads a large increase of acidity, which has been shown in many studies to greatly increase the secretion of growth hormone (GH), even as much as 290% over normal levels. As lactate increases, the pH level decreases, which stimulates the pathway responsible for stimulating the release of GH, and as we all know, GH is hugely important in the growth of muscle.
Low intensity occlusion training has also been shown to stimulate the mTOR pathway, the pathway responsible from stimulating muscle protein synthesis. This essentially means that the body is primed to use protein and amino acids to build new and larger muscle fibres as a response to stimulus (training).
The restriction of blood greatly limits the amount of oxygen available to muscles to use as a fuel. This sounds like a bad thing, but it actually works in our favour to build muscle. This is because during low intensity exercise slow twitch muscle fibres will be recruited to do the workload. However, these slow twitch muscle fibres rely on oxygen to fuel them. This means that in the low oxygen environment created by BFR, the fast twitch muscle fibres will very quickly take over the workload. This is beneficial because fast twitch muscle fibres have a much greater capacity for growth and are normally only recruited by high intensity exercise.
How to implement it
Elastic knee wraps, medical tourniquets or small resistance bands can all be used as a device to sufficiently occlude the blood flow to the target muscles. Where the wraps are placed is dictated by the muscle group you are looking to target. Targeting the upper leg muscles (quads and hamstrings) would require the wraps to be at the very top at the leg, just under the hip joint. Targeting the calves requires the wraps to be placed just under the knee. Occluding the upper body is a little trickier when trying to target the larger chest, shoulder and back muscles. Biceps and triceps can be easily occluded effectively you using the wraps just under the arm pit and shoulder joint. However, this same wrap placement can also be effective for chest and back but with slightly different mechanisms. It is thought that occluding the arms during bench press for example, would lead to the triceps fatiguing significantly faster, and thus recruiting a greater number of chest muscle fibres to complete the workload. The same could be said for occluding the biceps for back training. This would also still lead to the increased release in GH as stated previously.
The tightness of the wraps can be tricky to start with and may require some experimentation, but realistically the aim is reach a level of tightness of 7 for the legs and 5/6 for the arms (10 being the tightest you can get them). This should be enough to occlude blow flow out but not blood flow in. Wraps should be left on for the entire duration of the 4 working sets to get the desired effect and fluid build up.
The nature of this training method will also mean that the amount of weight you will be using will be significantly less. You should be working within a range of 20-50% of your 1RM as you will fatigue very quickly, making higher weights impossible (and possibly counterproductive). You should not be going heavy with occlusion at all, if you are doing it right, then a max of 50% of your 1RM should easily be more than enough to elicit the correct response. Some of the studies showed that working with 4 sets of reps at 30-15-15-15 to be the most effective.
Maintaining long periods of high intensity or heavy weight training can be extremely fatiguing on the nervous system, joints and ligaments. With occlusion training you can achieve almost the same stimulus as regular high intensity hypertrophy training without the additional load and stresses on the joints and central nervous system caused by heavy weights. This make occlusion training ideal for maintain high levels of stimulus whilst having a break from heavy loads or regular high intensity training. It also means that it is an excellent way to train around injuries, particularly with very common knee and elbow injuries.
BSc Sports Biomedicine and Nutrition
1. Kacin A, & Strazar K (2011). Frequent low-load ischemic resistance exercise to failure enhances muscle oxygen delivery and endurance capacity. Scand J Med Sci Sports, 21, e231-241.
2. Wilson JM, Lowery RP, Joy JM, Loenneke JP, & Naimo MA (2013). Practical Blood Flow Restriction Training Increases Acute Determinants of Hypertrophy Without Increasing Indices of Muscle Damage. J Strength Cond Res, epub ahead of print.
3. Loenneke JP, Abe T, Wilson JM, Ugrinowitsch C, & Bemben MG (2012) Blood flow restriction: how does it work? Front Physiol, 3, 392.
4. Loenneke JP, Wilson JM, Marin PJ, Zourdos MC, & Bemben MG (2012). Low intensity blood flow restriction training: a meta-analysis. Eur J Appl Physiol, 112(5), 1849-1859.
5. Loenneke JP, Fahs CA, Wilson JM, & Bemben MG (2011). Blood flow restriction: the metabolite/volume threshold theory. Med Hypotheses, 77(5), 748-752.
6. Loenneke JP, Fahs CA, Rossow LM, Abe T, & Bemben MG (2011). The anabolic benefits of venous blood flow restriction training may be induced by muscle cell swelling. Med Hypotheses, 78(1) , 151-154.
7. Loenneke JP, Wilson GJ, & Wilson JM (2010) A mechanistic approach to blood flow occlusion. Int J Sports Med, 31(1) , 1-4.
8. Schoenfeld, BJ (2013). Potential mechanisms for a role of metabolic stress in hypertrophic adaptations to resistance training. Sports Med, 43(3), 179-194.
9. Loenneke JP, Abe T, Wilson JM, Thiebaud RS, Fahs CA, Rossow LM, & Bemben MG (2012) Blood flow restriction: an evidence-based progressive model. Acta Physiol Hung, 99(3) , 235-250.
10. Thiebaud RS, Yasuda T, Loenneke JP, Abe T (2013). Effects of low-intensity concentric and eccentric exercise combined with blood flow restriction on indices of exercise-induced muscle damage. Interven Med Appl Sci, 5, 53-59.
11. Lowery RP, Joy JM, Loenneke JP, Oliveira de Souza E, Weiner S, McCleary S, & Wilson JM (2013). Practical blood flow restriction training increases muscle hypertrophy during a periodized resistance training program. National Strength and Conditioning Conference, J Strength Cond Res supplement.