Blood Flow Restriction Training

Guide and Uses of Blood Flow Restriction Training

Blood Flow Restriction training (BFR) is a technique widely used in the gym to potentiate increase in muscle mass. You may have seen it of even try, but does it work? In this post we'll go through the science and biochemistry behind all this, to later conclude wether it works or is a waste of money and time.

WHAT IS BLOOD FLOW RESTRICTION?

As its name may suggest from a start point, Blood Flow Restriction is a training technique performed using low loads in combination with blood flow oclusion. It aims to simulate the hypertrophyic effect of high loads (source). The combination of higher loads and lower loads using Blood Flow Restriction seems to potentiate muscle hypertrophy, therefore improving the process (study).

This technique was postulated and later patented by a Japanase ex-footballer called Yoshiaki Sato. He found out that using occlusion strategically could benefit his recovery from an ankle injury and minimize potential muscle loss.

The occlusion bands are mainly used in the upper and/or lower limbs. By doing these, less blood is pumped through and there's less oxygen available in the muscle being contracted (source). Not only that, but there are some other mechanisms behind blood flow restriction by which it could be used as a protocol to potentiate muscle gains.

SCIENCE BEHIND BLOOD FLOW RESTRICTION

INDUCES METABOLIC STRESS

This training technique is mainly known for the restricted oxygen available in the muscle being contracted. But this is not all. Because arteries are stronger and more resistant than veins, the occlusion bands will "close" blood flow back to the heart, while some blood will keep flowing to the peripherical tissues. This simply leads to oxygen accumulation and higher metabolite accumulation.

As we discussed in an earlier post about metabolic stress (click HERE), blood flow restriction can potentiate it by inducing the accumulation of metabolites in muscle cells. The accumulated species, consequence of resistance training in combination with limb occlusion , will regulate different pathways and hormones to potentiate muscle hypertrophy.

INCREASE MUSCLE ACTIVATION

Blood flow restriction protocols and metabolic stress have shown to increase muscle fibre recruitment (study). More fast-twitch fibres are activated by inhibiting alpha motoneurons, supplying the action of slow-twitch fibres. If there are more fibres recruited and activated, muscle contraction is enhanced and the ability of perform the exercise to a great intensity is also potentiated. However, this novel strategy still needs of more research.

POTENTIATES ANABOLIC PATHWAYS

One of the pathways being regulated in mTORC1, highly associated with muscle protein synthesis and anabolic functions (study)(study). Intracellular hydration down-regulates mTOR, and blood flow restriction seems to improve hydration (study). In addition to that, blood flow restriction also potentiates myogenic pathways involved in satellite cells proliferation and addition of new muscle cells to muscular structures (study).

Blood flow restriction is also associated with a lower gene expression of myostatin (study). This protein negatively regulates muscle growth, and its down-regulation can potentiate muscle hypertrophy.

INDUCES HYPOXIC CONDITIONS

Hypoxia is induced by the use of blood flow restriction strategies. It has been associated with higher mitochondrial biogenesis and msucle hypertrophy (study). Not only that, but it may also potentiate the sympathetic neural activation of muscle, creating higher neural adaptations (study).

Although hypoxic conditions may improve muscle hypertrophy, there are some aspects we should consider. It has also been suggested the negative effect it may have on muscle fatigue. The restricted oxygen makes the exercise harder to be performed in terms of energetic availability. In this study, they found that blood flow restriction negatively affects muscle fatigue (study)

Blood Flow Restriction Training

DOES BLOOD FLOW RESTRICTION WORK?

So far we have seen that theoretically blood flow restriction training protocols may work to take muscle hypertrophy to a higher extent. But what happens in real life?. In this section we'll cover some of the studies investigating practical applications of blood restricted protocols in humans.

In this meta-analysis (meta-analysis), the authors collected all the literature available related to blood flow restriction and muscle size. The conclusions, for our luck, were surprisingly consistent. When compared to low training, the addition of blood restriction induced higher increase in muscle size. In addition to that, the called Kaatsu walk (walking with the occlusion bands) got better results in muscle size than walking alone.

In this calisthenic group using blood flow restriction, increases of muscle size were higher when compared to control. They also investigated plasma concentrations of growth hormone in both groups, finding considerably higher concentrations in the flow restricted group (study)

There is also some evidence supporting the cross transfer effect of interconnected muscles (study). Subjects using blood flow restriction showed higher muscle hypertrophy when performing a biceps curl (50% RM) and leg extension (30%RM). While both groups performed the biceps curl without occlusion, leg extension was performed both with and without it. The group with occlusion showed higher muscle increase in the biceps, suggesting the cross transfer effect priorly mentioned.

The sciene available to date shows Blood Flow Restriction training to be a feasible strategy to potentiate muscle hypertrophy. To recapulate how blood flow restriction works, it induces muscle hypertrophy by providing an hypoxic environment, increase muscle activation and potentiate metabolic stress and anabolic pathways.

TAKE-HOME MESSAGES:


  • BFR is performed using low loads of 25-50% RM and low rest times between sets

  • The limited oxyegn provides hypoxic conditions and induces muscle adaptations

  • Sleep deprivation is associated with lower muscle recovery and suboptimal muscle hypertrophy

  • Fiber type I are highly activated during BFR, simulating the use of heavy loads

RECOMMENDED USE

This training technique is not for everyone. We saw that this strategy mainly enable us to induce muscle adaptations without the need of using high loads, but that doesn't mean adaptations are higher than with high loads. With than information you may guess who can benefit the most from this protocol, but we'll go through it anyways.

Injured or bedridden subjects trying to mantain muscle mass could potentially benefit by 1) walking and doing normal activitities with the occlusion bands, and 2) accelerating the recovery process by doing rehabilitation with occlusion bands.

Advanced trained subjects could also benefit from the use of Blood Flow Restriction, but it shouldn't be used all the time. This strategy requires high amounts of energy and muscle fatigue, being possibly conterproductive if done in excess.

During the performance of multi-joint exercise such as bench press or squat, the cross transfer effect of blood flow restriction training could potentiate the exercise (study)

Lastly, blood flow restriction could be used during the warmup of our sessions. The use of BFR could increase local blood flow on the muscle of interest and muscle oxygenation (study).

Uses of blood flow restriction training

PRACTICAL APPLICATIONS

Now we know what blood flow restriction training does, how it can influence muscle adaptations and who could potentially benefit from it. But how do I do it correctly?

The use of occlusion bands require of practice and a bit of experience. At first it might feel weird and even uncomfortable, but as you use them you will get used to it.

Blood Flow Restriction training is traditionally performed using low loads (25-50%RM) with low rest time between sets (30-60"). Not being totally an advanced-technique like dropsets, the goal of blood flow restriction is to accumulate metabolites and feel that 'muscle-burning'.

HOW TO USE THE OCCLUSION BANDS

The occlusion bands are used on the limbs, both upper (arms) and lower (quadriceps). Since there's no objectivity on the pressure exerted by the occlusion bands, you'll have to play around and get them tightly enough. In a scale of 1-10, aim for 6-7 in both limbs. However, legs are more likely to be under slightly higher pressure due to the bigger muscle size. So take that into consideration.

Muscle-burning and soreness after blood flow training is usual and you shouldn't be afraid of that. In fact, if there's no soreness at all after your first session, that indicates you haven't put enough pressure on your limbs.

TYPES OF BANDS

Personally, I have only used this technique training once before, and I cannot recommend any occlusion bands based on my experience. But that's where Google and other blogs can help us. After doing some 'surfing' on the web, I found two main types of occlusion bands:

  1. Elastic bands
  2. Belt bands

What are the pros and cons of each ones? Again, my experience is not enough to recommend one or another, but based on this website (post) we can discuss which one might be for you.

While elastic bands are more adaptable and easier to set up, they may lose tightness over time. Since you have no control over the pressure, they are sightly less accurate.

Belt bands, on the other hand, are more accurate since you can adjust them to your desired pressure. But the presence of the belt and the buckle might be uncomfortable and pinch your arm/leg once in a while

PERIODIZE THE USE OF BFR

As we said before, blood flow restriction shouldn't be used all the time.  It should be see as another tool of our 'tool box' to induce muscle gains. If we use it too much, muscle adaptations may take place and the benefits will be lower.

It's recommended to use it at the end of the session, when the high muscle fatigue produced doesn't compromise the rest of the session. Also, start with bfr from the first session of your mesocycle is quite abussive. Leave it for later on the progression and leave that bullet for when you really need it.

TAKE-HOME MESSAGES:


  • BFR is not for everyone and shouldn't be used abusively

  • During warm-up, BFR could be used to potentiate muscle activation

  • The use of occlusion bands require of practice and experience

  • End of the session and/or late on the mesocycle are recommended for the use of BFR

CONCLUSION

In this post we have seen what Blood Flow Restriction training is and why it works. Scientific evidence behind concludes this strategy to be useful and feasible for muscle hypertrophy. However, not everyone should use them. Recommended use are mainly for advanced trained subjects, bedridden, or going through a muscle recovery.

I hope after reading this post you are now able to explain and understand what's blood flow restriction and the interaction with different mechanisms to induce muscle hypertrophy. If there's any doubts regarding this post, feel free to leave it below in the comments section.

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