Blood Flow Restriction Training (BFR): The next big training innovation or just a fad?

If you've ever wondered whether there's anything to the concept of Blood Flow Restriction Training and whether it's something that could be a valuable addition to your training plan, then hopefully this article will be of some help.

Note: Please consult a doctor before starting a training program that includes Blood Flow Restriction Training techniques, especially if you suffer from cardiovascular disease or problems with blood vessels or circulation.

What is the concept of Blood Flow Restriction Training?

To fully understand the theory behind Blood Flow Restriction Training - BFR for short - it is important to first take a look at how blood flows through your body. The circulatory system is a closed cyclical system with the heart at the center. Oxygen-enriched blood enters the heart and is pumped with great force into the arteries. The arteries transport the oxygen-rich blood to all the tissues of the body, including muscle tissue.

For the sake of simplicity, let's use the biceps as an example. As the arteries approach the muscle, they become thinner and thinner until they become so thin that the nutrients and oxygen diffuse through the walls of the blood vessels into the surrounding tissue. These super-thin blood vessels are called capillaries.

After the blood has released its nutrients and oxygen, it is taken up by more capillaries, which transport this blood into larger blood vessels called veins. The veins passively transport the now deoxygenated blood back to the heart. Once back in the heart, the deoxygenated blood is pumped into the lungs, where it is re-oxygenated before returning to the heart, from where it is pumped back into the arteries to start the whole cycle again.

The force of the heart's initial surge is sufficient to move the blood from the heart, through the arteries, through the capillaries, into the veins and back into the heart, while overcoming all other obstacles such as gravity, constriction of blood vessels by plaques, etc.

From this description, it is easy to see that the blood flow velocity in the arteries is much higher than in the veins. Imagine that you are pushing a toy car across the floor. The initial push (the heartbeat) gives the car a useful amount of acceleration, but the further the car moves away from you, the slower it will become.

What is Blood Flow Restriction Training?

The goal of BFR training - which is also known as occlusion training - is to maintain arterial blood flow while restricting the venous return of blood to the heart: we want nutrients, hormones and oxygenated blood to reach the muscle while delaying the outflow of blood.

This is achieved by using a blood pressure cuff, a knee bandage or anything else that can be placed tightly around the arm or leg close to the attachment point on the trunk. If we use the arm muscles as an example, then the bandage would be placed tightly around the upper arm as close to the shoulder joint as possible to create a congestion of blood in the arms.

This is believed to have a positive effect on hypertrophy while allowing much lighter weights to be used than in conventional training.

How is it possible to restrict venous return of blood without restricting arterial inflow to the muscle?

Let's think back to the description of blood circulation for a moment. The blood in the arteries flows at a much higher speed and pressure than the blood in the veins. Restricting arterial blood flow therefore requires a much higher pressure than is needed to restrict venous blood flow, as blood flow in the veins is much less powerful. Think of one of those movies where someone suffers an injury and the blood gushes out in pulsating streams. This represents an arterial injury where the blood behaves accordingly due to the high pressure. If a vein is injured instead, the blood flows slowly and evenly out of the wound.

How does BFR training work?

The exact mechanisms by which BFT training works are still unclear, but the most likely theory agreed upon by most experts is that it has something to do with increased metabolic stress.

Muscles release growth factors and metabolic waste products such as lactic acid (lactate) into the bloodstream in response to resistance training. These growth factors and metabolic by-products are usually removed quickly by the normal blood circulation. By limiting the venous return flow of the blood, these growth factors and metabolic by-products remain in the muscle for a longer period of time during BFR training and therefore have more time to interact with the corresponding receptors in the muscle tissue.

Accumulation of metabolic by-products such as lactic acid increases intramuscular acidity and may promote hypertrophy and growth hormone release (although it has been shown that acute increases in growth hormone levels do not significantly affect muscle hypertrophy, it is still worth mentioning).

The increased acidity and the accumulation of lactic acid are responsible for the "burning" sensation in the muscle that we all know and love.

But even though we love this feeling, our body does not.

Our body does everything it can to increase the flow of oxygen to this area to reduce acidity and restore the natural balance. It does this by increasing the respiratory rate and increasing arterial, oxygenated blood flow (increased blood supply by dilating the veins aka pumping), but it can only do this for so long.

When the body is no longer able to manipulate respiration or blood flow sufficiently to balance tissue acidity, we reach an anaerobic ("no oxygen") state. As we struggle through the muscle burn, the acidity level in the muscle tissue continues to rise until we reach the point of muscle failure. Type II muscle fibers are activated during this anaerobic phase, which is important because they have the greatest potential for growth.

Blood Flow Restriction training increases the amount of deoxygenated blood in the area, which helps to create an anaerobic environment. The result? We reach an anaerobic environment faster and it lasts longer.

How does this work in practice? How tight should the cuff be? What are the best set and repetition ranges? How often should you train in this way

As already mentioned, the bandage should be as close to the body as possible when viewed from the corresponding arm or leg. It is difficult to determine an optimal tightness or tightness of the bandage due to individual factors such as circumference of the arm or leg, body fat percentage, skin thickness, etc.. However, studies seem to agree that a large estimate of 7/10 of perceived maximum tightness is a good guide.

Perform 3 to 5 sets at 20 to 50% of your maximum weight for one repetition (1 RM weight) until muscle failure is reached, keeping the band tight for the entire duration. The rest intervals should be 30 to 60 seconds between sets. After the last set, open the bandages to restore blood flow to the muscle.

As for how often a BFR workout should be performed, my personal opinion is that BFR training should be used like any other intensity technique such as rest-pause, descending sets, etc. that aims to increase metabolic stress.

Is BFT training better than simply moving weights? After all, for centuries exercisers have become more muscular and stronger simply by moving heavy things... In this context, it should be kept in mind that science only gives us a hint in a certain direction that we can investigate further and that such new findings should not be seen as the non-plus-ultra that replaces everything that has gone before.

Scientific research gives us trends and averages, but we are not all the same. In this context, it should be mentioned that scientific research shows that BFR training appears to be more effective for muscle hypertrophy than conventional hypertrophy training with appropriately adapted weights.

This means that BFR training produces the same amount of hypertrophy as conventional training while using significantly lighter weights. It has been shown that BFR training can increase muscle hypertrophy with weights in the range of 20 to 30% of 1RM weight, which is significantly less weight than what is typically required for conventional training.

When comparing BFR training to conventional strength training, scientific research has concluded that both types of training have similar effects on strength. This means that moving lighter weights during BFR training can increase strength to the same extent as conventional training with heavier weights.

If the weights were adjusted so that both groups trained with exactly the same weights, then BFR training could increase strength to a greater extent than conventional training.

In this context, however, it should also be mentioned that there are studies that show that BFR training is inferior to conventional training when it comes to increasing strength. Scientific research supports that when it comes to strength, specificity of training is key.

So what's the bottom line on strength? As the old adage in strength training goes, "If you want to lift heavy things, you have to lift heavy things."

BFR training has also shown promising results in the field of therapy and rehabilitation training.

Scientific studies have shown that subjects experienced increased serum growth hormone levels, increased thigh muscle size and increased isometric 1RM after simply walking on a treadmill with BFR bandages attached to their legs.

Research also shows that training with BFR supports after ACL reconstruction surgery resulted in better strength maintenance and less muscle atrophy compared to conventional therapy. Better maintenance of strength and less atrophy were also observed when BFR training was used in the phase following immobilization of the ankle.

It seems that BFR training could be an effective tool with a wide range of possible applications. However, variables such as speed, strength, endurance, etc. require further investigation.

Is BFR training safe and harmless?

To be on the safe side, you should discuss the use of BFR training with a qualified physician in advance. Contraindications for such training include a history of venous thrombosis, pregnancy, varicose veins, high blood pressure and cardiovascular disease.

Excessive blood pressure and prolonged ischemia (reduced blood flow) can lead to necrosis (cell death) of body tissue. Even though the BFR guidelines described in this article do not use excessive pressure and the pressure used is not maintained over a long period of time, you should still be careful.

Stop exercising immediately and contact a doctor straight away if you experience severe pain, dizziness, nausea or a numb/tingling sensation in the relevant areas.

Keep in mind that all gym workouts carry a certain level of risk. If not sufficiently respected or performed correctly, almost anything can be harmful or dangerous. Even when using a perfect form of training, there is always some risk of injury.

What is the information you should take away from this article?

• In a BFR workout, the goal is to achieve fatigue, a pooling of blood and a muscle burn faster and with less weight/work.
• Wrap the part of your arm or leg as close to the torso as possible (below the shoulder and high on the inner thigh) with a pressure that is about 7/10 of your self-assessed maximum pressure.
• Perform 3 to 5 sets to muscle failure with 20 to 50% of your maximum weight for one repetition (1RM weight), keeping the muscle contracted the entire time.
• The rest intervals between sets should be 30 to 60 seconds.
• Remove the bandage after the last set to restore blood flow to the muscle.
• Although it has been shown that BFR training can increase hypertrophy and strength, it seems to have a stronger positive effect on hypertrophy than on strength. When it comes to maximizing strength development, it may be more effective to stick to traditional training with heavy weights.
• BFR training appears to be safe and harmless. However, you should still consult a doctor before undertaking such training for the first time.