What is BFRT? (Blood Flow Restriction Training)

Training based on flow restriction or BFRT (Blood Flow Restriction Training), is a method that consists of using cuffs or bands to restrict muscle blood flow during low-intensity resistance exercise with the aim of stimulating hypertrophy. But how does this affect muscle?

The hypertrophic mechanisms of blood flow restriction are associated with metabolic stress through the accumulation of metabolites. Arterial blood flow to the muscle is moderately  restricted, but it will be the flow of venous blood from the muscle itself that will be totally restricted. This will cause a situation of intracellular hypoxia, reducing the amount of oxygen that reaches the muscle, increasing metabolic waste (AMP, Lactate). When this happens, the fast-twitch fibers, which have the greatest growth potential, are recruited to a greater extent in addition to activating the satellite cells.

KAATSU Method

This type of training emerged in 1966, with the KAATSU method (KA: Additional, ATSU: Pressure), created by Dr.  Yoshiaki  Sato. The BFRT consists of surrounding a limb in its upper part and occluding the veins to prevent venous return, that is, that the blood returns to the heart again, therefore, our muscle will be full of blood.

The advantage of blood flow restriction training is that it allows the person to exercise with less intensity, but still get the benefits of high-intensity training. Multiple series of low-intensity BFR (20-40% 1RM) provide a metabolic stimulus similar to the classic hypertrophy stimulus (70-80% 1RM)

As for the material, it would be ideal to have compression sleeves, with which we can perfectly control the pressure we need in each of our needs. If we have compression sticks like those of Bstrong, through  app.gobstrong.com,  we can control the pressure we exert. In addition, it has numerous videos that can serve as a guide to learn more about the BFRT.

Even so, we can also use more affordable material such as compression bands, usually cotton and elastic with Velcro that fulfill a very similar function although it does not allow us to control the real pressure exerted. We can use the perceived pressure value to control the intensity. It is recommended to exercise 6/10 arms and 7/10 on legs

If we begin to notice tingling in the extremities, whitish fingers or that our arm falls asleep, it will mean that we have tightened excessively and we must remove the compression band immediately. It will always be better to squeeze less than to squeeze too much.

Figure 1. Example of an occluded arm with a compression band

How can I get started with the BFRT?

It is recommended to surround the proximal area of our limbs, that is, in the closest area of the groin in legs and the closest area of the armpits in arms. Never surround joints, since the effectiveness would not be appropriate. It is also very important to note that our goal is to prevent venous return and as we already know, the veins are in a more superficial area than the arteries. If we squeeze our limbs excessively, we will be preventing the arterial flow and that would be very harmful to our body.

On the other hand, we must talk about that not only the occluded muscles benefit but also have improvement in the muscles near them. The nervous system locates enormous fatigue in the restricted muscles, so it exerts a compensation strategy by activating to a greater extent the muscles that participate in the movement but are not in a state of occlusion.

In the study of Yasuda et al (2010) it was observed that in the realization of bench press with occlusion in both arms, the pectoral was activated 16% more than without flow restriction.  Even so, the evidence tells us that it is better to perform compound exercises intensively and leave for mono articular or isolation exercises the flow restriction.

How do I apply it to my Workouts?

The main objective of this type of training is basically to increase our muscle hypertrophy using much lower loads than we usually use (20-40% 1RM). Through occlusion, an imbalance is created in the homeostasis of the muscle that is contracting, stimulating local and systemic anabolic mechanisms.

The general recommendations are usually to perform 50-80 repetitions per exercise divided into 4 sets of 15-30 reps with low loads as we have mentioned above. Being an exercise with a much lighter load, which will not involve an excessive effort in terms of mechanical tension, it is important to perform the exercise with a  complete ROM and take advantage to focus the mind-muscle connection, that is, we will seek to focus our attention thinking about moving the external load and feel the contraction of the muscle. It is not necessary to reach muscle failure.

As for rest, it is recommended to leave 30″-45″ between sets and 1′ between exercises in order to achieve more pumping and more lactic acid, thus increasing metabolic stress.   It is very important not to remove the cuffs or bands during the interseries recovery periods to favor a sufficient accumulation of venous blood.

If you are a beginner in this type of training, it is better to start with 1 day per week and gradually increase the days to 3 days per week.

Figure 2. Example of legs occluded with a compression band

Can I replace a classic workout with BFRT?

When both protocols (with and without occlusion) are taken to maximum fatigue, no differences are found between one and the other (Farup et al., 2015) because the mechanical stress generated is the same. The mechanism may not be the increased induction of metabolites, but the fact that occlusion techniques decrease the number of repetitions needed to reach muscle failure (Loenneke et al., 2012).

Although it sounds like the ideal workout to achieve muscle hypertrophy, the answer to this question is no. This type of training is just one more tool that we can use in our planning, but it is not recommended to do more than 3 times a week.

        Figure 3. Main mechanisms of hypertrophy (@rubrs_go)

Is this type of training for everyone?

Of course, like all training, they have certain contraindications that we must take into account. Occlusion increases blood pressure and may be counterproductive with patients  diagnosed with hypertension. Therefore, if you are a person who suffers from heart failure, hypertension, pregnancy or bleeding disorders, this type of training is not for you.

Bibliography

• Schoenfeld, BJ (2013). Potential mechanisms for a role of metabolic stress in hypertrophic adaptations to resistance training. Sports Med, 43(3), 179-194.
• Scott, B. R., Loenneke, J. P., Slattery, K. M., & Dascombe, B. J. (2015). Exercise with blood flow restriction: an updated evidence-based approach for enhanced muscular development. Sports medicine (Auckland, N.Z.), 45(3), 313–325.  https://doi.org/10.1007/s40279-014-0288-1
• Yasuda, T., Fujita, S., Ogasawara, R., Sato, Y., & Abe, T. (2010). Effects of low-intensity bench press training with restricted arm muscle blood flow on chest muscle hypertrophy: a pilot study. Clinical physiology and functional imaging, 30(5), 338–343. https://doi.org/10.1111/j.1475-097X.2010.00949.x
• Centner, C., & Lauber, B. (2020). A Systematic Review and Meta-Analysis on Neural Adaptations Following Blood Flow Restriction Training: What We Know and What We Don’t Know. Frontiers in physiology, 11, 887.  https://doi.org/10.3389/fphys.2020.00887
• Nascimento, D., Petriz, B., Oliveira, S., Vieira, D., Funghetto, S. S., Silva, A. O., & Prestes, J. (2019). Effects of blood flow restriction exercise on hemostasis: a systematic review of randomized and non-randomized trials.  International journal of general medicine, 12, 91–100.  https://doi.org/10.2147/IJGM.S194883