Understanding Blood Flow Restriction

Blood flow restriction tourniquets — those arm and leg bands that look a little like narrow blood pressure cuffs — made a splash at the 2020 Tokyo Olympics. Some top performing track athletes and swimmers such as Michael Andrews and Galen Rupp used them while warming up or cooling down.

BFR was hailed as “the new cupping” by some, referring to previous Olympic Games when many swimmers showed up with large circular marks on their skin from the ancient Chinese practice of cupping. Like cupping, BRF is the latest trend in professional sports and fitness that might also have applications for the less-athletic set.

What Is BFR?

Caroline Brunst, a physical therapist and athletic trainer with the Ohio State University Wexner Medical Center in Columbus, describes blood flow restriction training as “a novel technique that has gained popularity in recent years.” It’s also known as tourniquet training, because it involves the use of a cuff or tourniquet system on “the proximal end of an extremity,” meaning the upper arm or upper leg.

Most systems use a pneumatic tourniquet, in which the band is inflated with air “to a pressure high enough to maintain arterial flow while restricting venous return,” Brunst explains. This means that the cuff inflates enough to slow the return of blood from the muscle to the heart, but isn’t so tight that it cuts off all circulation, or even restricts blood flow to the working muscle.

This blockage of blood flow from the muscle back to the heart is the key component of BFR. The presence of the extra blood is believed to send signals to the brain that this muscle is working harder than it really is. This type of physical stimulation can help build muscles, “similarly to what is noted at higher-intensity training with more resistance,” Brunst says. In other words, it boosts the effects of strength training.

A 2019 study in the Journal of Applied Physiology that examined a group of men aged 55 and older during a 14-week period, found that BFR paired with low-intensity resistance exercise offered muscle building gains similar to those achieved through high-intensity resistance exercise.

Origins of BFR

BFR has older origins, says Steven Munatones, CEO and co-founder of KAATSU Global, Inc., the company that makes the original blood flow modification device called KAATSU.

“KAATSU is a Japanese word that means ‘additional pressure'” Munatones says. The idea was first developed by Japanese physiologist and powerlifter Dr. Yoshiaki Sato in 1966.

Sato developed the KAATSU system, which is hailed as the first of the blood flow restriction or blood flow modification systems. There are a variety of other brands and types of blood flow restriction devices on the market today, and they can range from about $25 for the most basic model, to several thousand dollars for the high end options.

How it Works

Blood flow modification or restriction devices like KAATSU are designed to add pressure to the limbs. Munatones says that KAATSU equipment “gently applies pressure to slow down the venous flow — or the return of blood from the limbs to the torso.”

The equipment does not block the flow of oxygenated blood from the heart to the muscle, however, “which is extremely important. While tourniquet and blood pressure cuffs are specifically designed to cut off arterial flow from the torso to the limbs, KAATSU equipment is designed specifically to allow arterial flow to continue unimpeded and only to slightly modify the venous flow.”

Users can set the pressure at variable or constant levels, and you may want to start with very low pressure and build up over time to more intense restriction. Depending on the program, that pressure will stay elevated for usually about 30 to 45 seconds before releasing, and may also cycle through on a set series or repetitions.

A small computer powers these pressure changes in the KAATSU device, and users can set it to a wide variety of programs to help reach their goals, whether that be building speed, stamina, strength, flexibility or recovery and rehabilitation.

Munatones says that when your limbs are engorged with blood and you move, “then a number of biochemical reactions occur naturally in the vascular system and brain as a result.” He says this includes increased secretion of several hormones and other compounds including:

Human growth hormone. HGH is a hormone produced by the pituitary gland that helps muscles grow and cells regenerate. It’s useful for building and repairing tissues in the body and is especially important after intense physical exercise to repair and build stronger muscles.

Insulin-like growth factor 1. IGF-1 is a growth hormone that’s similar in structure to insulin, but works like HGH in building and repairing muscles in adults.

Vascular endothelial growth factor. VEGF is a protein that stimulates the formation of new blood vessels. When blood vessels are obstructed and less oxygen is reaching the tissue, VEGF is released to help new blood vessels develop to get around the blockage.

Brain-derived neurotrophic factor. BDNF is a protein that stimulates cellular growth and repair in the brain and nervous system. Exercise promotes the release of BDNF in the brain.

Nitric oxide. NO is a compound that stimulates growth hormone secretion. It’s also involved in vasodilation, and when blood vessels are compressed, that can increase the release of NO.

Plasmalogens. These lipids, or fats, can help protect other lipids and lipoprotein particles from oxidative stress – that’s the daily wear and tear cells undergo from the stress of daily living, exposure to toxins, and other similar factors. This makes their function similar to that of antioxidants, which are found in many plant-based foods.

Ceramides. These fats found in skin cells can also help build more resilient blood vessel walls.

Testosterone. The male sex hormone testosterone is well known for helping increase strength and muscle size.

“It’s this hormonal and metabolic response that leads to athletic gains and enhanced rehabilitation and recovery,” Munatones explains.

“It’s kind of a biohack,” says Chris Morgan, a Massachusetts-based swimming coach and chief aquatic officer at KAATSU Global. He adds that the device can provide a more efficient way to get the intensity you need from a workout.

For example, with his swimmers, instead of having them swim 8 times 200 meters, (1600 meters total) Morgan will have them do 16 times 25 meters (400 meters total) to get the same end result in a quarter of the time. “And you’re also not going to tear your shoulders apart. You’ll have less connective tissue damage and less bone grinding, especially if you’re a land athlete” because of that reduced training volume.

Who Can Use BFR Training and Devices?

Strength and power athletes, such as those doing explosive sprinting or those who want big, weightlifting muscles are obvious candidates for adding BFR to their training regimens to reap its benefits of less wear-and-tear on the body.

But other individuals may also find a benefit. Thomas Roe, an American Council on Exercise certified personal trainer, endurance athlete, founder of TRoe Fitness and owner of Local Moves Studio in San Antonio, Texas, says “an ideal candidate is anyone who has trouble lifting heavy loads, which includes your own body weight. Think elderly or those who aren’t physically active prior to going into the surgery or therapy session.”

Munatones agrees that older adults, sedentary people, folks who lack mobility and balance, as well as those with musculoskeletal injuries who are recovering can also be considered ideal candidates.

If you’ve had surgery or are undergoing rehab for an injury “the traditional strengthening model may not be feasible due to pain, instability, swelling or other factors,” Brunst says. If that’s the case, a sports medicine practitioner may use BFR “to facilitate improvements in strength and function.”

The protocol can also help busy individuals get more out of each workout in less time, and even use the devices while doing house work or walking the dog to get a workout in without heading to the gym.

Is BFR Safe?

Brunst notes that people with certain conditions should steer clear of BFR training. These conditions include:

— Vascular disease.


Sickle cell trait or disease.

— Severe hypertension.


— Pregnancy.

— A history of deep vein thrombosis.

If you have any of these conditions, Brunst recommends talking with your physician and rehabilitation team to determine if BFR is safe and appropriate, or whether an alternative treatment option might be a better choice.

Still, Brunst concludes that “when performed with appropriate athlete selection and with a provider that has undergone sufficient training on BFR application, it has been shown to be safe with very few reported complications.”

Munatones agrees that over their 50-plus years of research and development, KAATSU devices have been found to be safe and “most, but not all, BFR equipment is safe.” However, with some of the less-expensive versions, particularly those that more closely mimic a blood pressure cuff “users can apply too much pressure or apply too much pressure for too long.”

It’s also possible to put the bands in the wrong places or complete exercises that aren’t compatible with consistent pressure. This is why KAATSU recommends working with one of their certified practitioners when starting this therapy. As with any exercise regimen, it’s best to clear use of BFR with your doctor before you start, particularly if you have any underlying medical conditions.

Munatones, who suffered a massive heart attack in 2016, says “I’m convinced that the primary reason why I’m alive is because I had been using KAATSU for over 15 years before I had my heart attack.” He also recovered quickly following KAASTU protocols for cardiac rehabilitation and is now back to competing in marathon swimming events.

That said, not everyone likes or wants these pressure devices as part of their training or rehab efforts. Roe, for example, doesn’t subscribe to this approach. “BFR really is a personal choice,” he says. “If it works for you or you achieve repair and recovery results, then stick with it. Personally, I think most injuries or post-surgery recovery can be accomplished with deep tissue massage, yoga or Pilates, stretching and strengthening or swimming.”

More from U.S. News

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Understanding Blood Flow Restriction originally appeared on usnews.com

Update 04/19/22: This story was previously published at an earlier date and has been updated with new information.

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