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BFRT: What Is Blood Flow Restriction Training, And Who Is It For?

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Although blood restriction therapy or BFR training has seemingly become popularized only recently, research into the benefits of BFR training has actually been going on for at least 20 years.

BFRT is now a recognized training and rehabilitation modality by the American Physical Therapy Association.

But, what is BFRT? How does blood flow restriction training work?

In this guide, we will cover the basics of BFRT, such as the BFRT meaning, how to do blood restriction training workouts and the benefits of blood restriction therapy.

In this guide, we will look at: 

  • What Is BFRT?
  • How Do You Do BFRT?
  • How Does BFRT Work?
  • Benefits of BFRT

Let’s jump in!

A tourniquet on an arm.

What Is BFRT?

Let’s start out with the BFRT meaning to get a clear understanding of exactly what it is.

Blood flow restriction training, also known as BFR training or BFRT, involves performing regular exercises while limiting the amount of blood flow to your arm or leg. The partial occlusion of your blood vessels is achieved by placing a blood flow restriction cuff or strap tightly around the limb.

Some amount of blood flow is still permitted to and from your arm or leg, but the pressure provided by the cuff or strap compresses the blood vessels and makes it more difficult for blood to circulate into the limb.

The overall purpose of blood flow restriction training is to induce the physiological effects of higher-intensity exercise while performing lower-intensity exercise.

How Do You Do BFRT?

What is interesting about blood flow restriction training is that it uses significantly lower loads than those traditionally thought to be necessary to induce muscle growth and muscle strength.

For example, most fitness experts suggest that for muscle building, which is known as hypertrophy training, you should use a load that is equivalent to 67 to 85% of your one-repetition maximum (1RM) for an exercise.

A physical therapist helping a patient do BFRT.

Your 1RM is the amount of weight that you can lift for exactly one repetition with the proper form of any given exercise. 

If you can use the same weight for two repetitions, you need to increase the weight, and you have not found your true 1RM. 

On the other end of the spectrum, if you have to “cheat“ or are not using the proper technique for the exercise, you need to decrease the weight until you are able to do so.

So, for example, if you can perform just a single rep of the bench press exercise with 200 pounds, then your 1RM for this exercise is 200 pounds.

Therefore, the amount of weight that you should be lifting in muscle-building workouts, according to the traditional framework, is 134-170 pounds (67-85% of 200 pounds) for 6-12 reps.

The load suggestions for increasing strength are even higher. Most strength training professionals recommend using loads that are at least 85% of your 1RM for the exercise.

In contrast, with BRF training, most of the guidelines suggest using low-intensity loads that are less than 50% of your 1RM while still inducing some of these same muscle-building and strengthening benefits.

A woman lifting a barbell at the gym.

How Does BFR Training Work?

Researchers theorize that the improvement in strength and increases in muscle growth achieved through BFR training using such low loads are primarily attributable to the metabolic stress that blood flow restriction training induces rather than the degree of muscle tension the weights put your muscles under.

In other words, when we think about what causes muscles to grow and what factors stimulate increases in muscle strength, we often think only of the mechanical tension that we place our muscle fibers under when we are lifting heavy loads.

However, there are also metabolic and hormonal changes that occur with resistance training, and these factors may be the ones primarily underlying the improvements in strength and muscle size seen with BFRT.

Metabolic stress seems to cause autocrine and/or paracrine actions, which, in turn, stimulate muscle growth.

A muscular man doing a bicep curl.

Essentially, by restricting blood flow to and from the muscles on the working limb, there is an accumulation of metabolic byproducts, and the muscles are forced to work in a relative hypoxic (oxygen-deprived) environment.

This increases the normal amount of metabolic stress your muscles may be experiencing under higher loads, so you can get away with using lower loads in conjunction with restricting blood flow through BFRT.

The relative oxygen deprivation and buildup of metabolites in the muscle due to restricted arterial and venous blood flow cause a more rapid accumulation of fatigue in your muscles, which helps then activate additional motor units and muscle fibers that would otherwise not be recruited to work when lifting such light loads. 

Additionally, the metabolic stress from BFR training signals anabolic pathways, which, in turn, alters the hormonal milieu to support muscle growth. 

In this way, blood flow restriction training can induce muscle protein synthesis to the degree that high-load resistance training under a traditional hypertrophy training framework can.

A person chalking up their hands before doing a deadlift.

Benefits of BFRT

Because BFR training allows you to use much lighter loads while still improving strength and triggering muscle growth, it is a particularly valuable training technique for those who are recovering from an injury or in the postop period following a surgery where it would be unsafe to use more resistance. 

BFRT can also be helpful for elderly individuals or those who otherwise have contraindications to lifting heavy weights but still want the benefits of doing so.

Because it is typically not possible to lift weights after surgery or during certain injuries, especially at the high loads traditionally recommended for muscle hypertrophy, many people experience muscle atrophy during an injury or after surgery.

In physical therapy settings, BFR training can be used to help attenuate muscle atrophy, if not even further, to help increase muscle strength.

In physical therapy and rehabilitation settings, training loads that are only equivalent to about 20 to 30% of your 1RM can be used to counteract losses in muscle mass and strength during the recovery period without increasing the risk of injury by overloading the healing muscles.

A man doing a bench press.

Moreover, one of the benefits of blood restriction training is that it increases your “muscle pump.“ 

Muscle pump refers to the visible swelling or increased plumping and size of muscles during exercise due to the accumulation of blood in the muscles.

Although most lifters mostly appreciate the aesthetic benefits of a good “muscle pump,” in which your muscles physically look larger and more vascular, there are actually physiological training benefits of a good muscle pump during a workout as well.

When you achieve a good muscle pump, blood is engorging and pumping into the muscle.

This causes the overall size of the muscle to swell, which stretches the fascia around the muscle. Fascia is the fibrous connective tissue that surrounds the bundles of muscle fibers (fascicles) within your muscle as well as around the muscle as a whole. 

Fascia is dense and fibrous, and although it can stretch, it is not as extensible and elastic as contractile muscle tissue.

However, a big muscle pump can help temporarily stretch the fascia, potentially creating more “space“ to provide room or “real estate“ for hypertrophy or muscle growth.

A muscular man doing a bicep curl with a barbell.

At the same time, because a muscle pump effect is caused by the muscles being engorged with blood, and blood carries nutrients that support muscle growth (such as oxygen, glucose, amino acids, vitamin C, zinc, copper, and magnesium) when you get a good muscle pump, your muscle fibers are bathed in a resource-rich pool filled with nutrients to maximize your gains.

It may seem counterintuitive that blood flow restriction would increase your muscle pump because it is reducing blood flow. 

Although it is true that while the blood flow is being restricted, you will not be able to achieve a muscle pump, when you remove the tourniquet that you are using to restrict your blood flow, the blood rushes to the muscles.

It is as if the floodgates are opened, and you get a rebound effect of hyperperfusion of the muscles. 

Rather than just getting whatever volume of blood they would have been receiving with patent arteries during exercise, there is a reactive increase in the blood flow to your muscles, as if trying to make up for whatever relative reduction had occurred during the BFRT.

A woman doing a bicep curl.

In this way, you get an augmented muscle pump after you remove the BFR strap or cuff.

Again, because blood carries all of the nutrients and resources necessary to repair and strengthen your muscle fibers, your muscles receive a bounty of “ingredients“ for muscle protein synthesis after blood flow restriction training.

Overall, blood flow restriction may help give you the benefits of lifting heavier weights while using lighter loads. 

Speak to your physical therapist or personal trainer about whether BFRT is a good option for you. There may be cases where restricting blood flow is contraindicated.

For more information on increasing your muscle gains, read our guide:  How To Build Muscle Fast, 5 Ways To Gain Muscle Mass.

A muscular man doing a bicep curl.
Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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