Occlusion/BFR training

It has always been believed that the only way to elicit muscle growth is by training with high mechanical load in the gym. This involves working in a 6-12 rep range, taking each set to failure throughout the majority of your session, and adding in some high rep/low rest work towards then end of your workout.

However, Occluded training, otherwise known as Blood Flow Restriction training (BFR), has shown more recently that a hypertrophy response (muscle building) is possible with much lower loads than how we would usually train.

Personally, I have used this on and off in my own training as well as with clients over the years, finding it to be moderately successful. But this article isn’t about contesting whether it works or not. The aim of this article is to discuss how BFR training works and the mechanisms by which it helps us add muscle, so that you have a better understanding of it and know how to apply it appropriately to your own training.

What is it?

BFR training is a form of training in which you restrict the blood getting to a muscle and then perform a weightlifting exercise that targets that muscle. This can be done using occlusion bands or a pair of wrist wraps. The tightness you are looking for is roughly an 8/10, whereby 10/10 would be as tight as you could make it.

BFR is most commonly used for training arms and legs. As such, the occlusion bands will most commonly be placed at the either the top of the arms or the top of the legs (Figure 1). As we are lifting, these will restrict oxygen from getting into the working muscle group, but it will also restrict the removal of the metabolic waste products (e.g., lactic acid) that are produced through muscle contraction.

How does it work

When looking at data, it seems that in order to elicit a hypertrophy response, one must be training with a load greater than 65% of your 1 Repetition Max (1RM). However, in bodybuilding we don’t tend to do 1RM work, we simply work in a 6-12 RM range, but the principles are the same. Without getting too complex, if you’re training to failure each set, you’re eliciting a hypertrophy response.With this in mind, what the data on BFR shows is that you can see a hypertrophy response using as little as 20-30% of your 1RM. This means that if your 6-12RM is 100kg on the leg press, you could instead use between 20-30kg and yield a similar muscular response.In practice, I will often program BFR training for one exercise, to be performed in 5 total sets. The first set will have a 20rep target, and the subsequent 4 sets will have a 12-15 rep target. The key here is that rather than resting till recovered, you only take 30s between each set, and keep the bands/wraps on in between.

If you have never done this, here’s a word of caution: the pain can be brutal! This is mainly due to the low oxygen environment created in the muscle, as well as the build-up of those waste products as stated above. By the time you get to set number 3, the burn is intense.

Mechanisms

By now, you know that three key components to building muscle: muscular tension, mechanical load, and metabolic stress. Without these, the addition of new muscle is simply not going to happen. With BFR training, in the absence of high mechanical load (weight on the bar) due to the 20-30% 1RM target for this style of training, we are left with only with muscular tension and metabolic stress as mechanisms to elicit hypertrophy. Interestingly though, this has not been clearly demonstrated by BFR research: that is, although it has been shown to have a potent hypertrophy-effect, the exact mechanisms have not been outlined. Therefore, it has just been assumed and theorised (based on the required change in mechanical load) that the addition of new muscle mass comes from muscular tension and metabolic stress.

What we need to consider is that when training with lighter loads, we can often do a better job of contracting the individual muscle fibres in a muscle group. The more contraction we have, the more metabolic waste products we also have, which shows how these two mechanisms work together. This is key, as many bodybuilders fail to progress their physique because they get trapped in trying to lift heavy yet get minimal recruitment of muscle fibres throughout their working sets. Moreover, with BFR training, due to the low oxygen environment, we can actually also see an increase in the recruitment of type 2 fibres, which are the target fibres for high mechanical load work, and as such, will help add new muscle.

Another added benefit of working at lighter loads is that we don’t see any muscle breakdown. This means that you will not experience much DOMS (delayed onset of muscle soreness) the next day or subsequent days after, so you’ll be able to train those muscle groups more frequently. If you can train more frequently, you will see more of a response because you’ll be increasing your training volume across the week.

Lastly, there are some studies which show an increase in the production of growth hormone and IGF-1 resulting from BFR training. Now, contrary to many beliefs, growth hormone is not directly involved in hypertrophy, but instead, it can serve as a protective role for tendons, ligaments and cartilage. As such, this suggests that BFR can be used as an effective recovery tool for athletes, allowing them to hold onto the muscle they have built, but also aid in increasing recovery.

It’s important to note here that if you are using anabolic steroids, an increase in IGF-1 can have an indirect effect on muscle growth as anabolic steroids will increase IGF-1 receptors in muscle and have a downstream effect on the muscle building pathway (known as MTOR).

Personal experience

Having used BFR training over the years, I stand by its benefits and its place within the sport of bodybuilding. Personally, I used this method back in 2019-2020 to add in more bicep work across the week as they were a lagging body part in my physique. When I compare pictures, they definitely did increase in size and density, but I always feel that there is time limit on how long you’ll see a response from this style of training.

As such, I would recommend using BFR for stints of roughly 8 weeks or so before I just suggest you look at changing your programming up to increase volume in your weaker areas. Looking back now, when using BFR, I was just stubborn and set in my ways, not willing to change how I train, and instead looked to add in more volume for the sake of it. Now in 2021, I train biceps 3 times a week and do one set day for them with zero occlusion training.

I have used it over the years with clients when the pickup an injury. I always find it fascinating how they hold onto the muscle they have and tend to recover quicker than they would do without it (refer back to my earlier point on growth hormone).

In summary, exercise-induced mechanical tension and metabolic stress are theorised to signal a number of mechanisms for the induction of muscle growth from BFR training. These include increased type 2 muscle fibre recruitment, increased levels IGF-1, increased levels of growth hormone and reduced muscle damage. BFR training can be used for an athlete recovering from an injury that isn’t able to load the injured tissue with heavy weights. An athlete already doing a lot of heavy lifting that needs extra hypertrophy work might benefit from this style of training if they can’t tolerate adding more heavy volume to their program.

Vaughan Wilson Bsc Hons

References

https://pubmed.ncbi.nlm.nih.gov/25249278/

https://thebarbellphysio.com/science-blood-flow-restriction-training/

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