Blood Flow Restriction Training, Explained Plainly

Most people arrive at the term Blood Flow Restriction the same way. A physical therapist mentions it.  A podcast brings it up.  A friend at the gym is wearing wide bands on his arms and says he gets pumped. Search online and the market is full of bands at every price point and BFR certifications abound with all kinds of claims that range from plausible to overstated.

This article explains what is scientifically known, what is contested, and what you should keep in mind before you buy anything or commit to a protocol.

What The Term Actually Means

Blood Flow Restriction, or BFR, refers to exercise performed with a band, cuff, or tourniquet wrapped around the upper arm or upper leg. BFR cuffs are either inflated or manually tightened to slow the blood from the torso to the limbs (called arterial flow) and the return of blood from the limbs back to the torso (called venous return).  BFR and KAATSU are often used interchangeably.   However, in contrast to BFR cuffs, KAATSU bands do not occlude the arterial flow.  That is, the arterial flow into the limbs continues while venous return is briefly and repeatedly modified The result of the KAATSU bands is a brief, temporary, and incremental pooling of blood in the muscles distal (i.e., below) the bands.  Due to the pooling of blood in the veins and capillaries, combined with simple movement or exercises, the body produces a robust hormonal and metabolic response that is normally only seen at much higher training loads.  In addition, the process of angiogenesis begins (i.e., where new capillaries form) while the elasticity of the vascular tissue within the limbs increases. 

Where did KAATSU come from?

The method was developed in Japan, beginning in 1966, by a young man named Yoshiaki Sato. He was attending a Buddhist ceremony with his legs folded under him, when he noticed that his calves felt pumped up, similar to how they felt at the end of a workout. He spent the next seven years figuring out what was happening to his muscles, ultimately designing elastic bands, while, testing tightening pressures, locations, and durations, and band widths, on himself. 

He named the method KAATSU, from the Japanese characters for that mean "additional pressure" in English. By the 1970s, Sato had opened the first KAATSU clinic in Tokyo.  Between 2004 and 2014, more than 12,000 patients including over 2,000 cardiac rehabilitation patients were tested on KAATSU at the University of Tokyo Hospital by a team of cardiologists.

A seminal paper, published in the Journal of Applied Physiology in 2000, described the mechanism of KAATSU - then referred to as moderate vascular occlusion - in peer-reviewed literature for the first time.

The term BFR, as a category, is a more recent terminology commonly used in America and Europe. BFR refers broadly to any method using a cuff or pressurized tourniquet during exercise or rehabilitation. The methods, equipment, and pressures used within that category vary considerably, which is the source of most of the confusion in the field.

What Splits The BFR Category

There are two fundamental approaches inside the BFR market. The first uses a wide, stiff cuff that compresses the limb at a constant, often high, percentage of the user's measured limb occlusion pressure. This is the approach favored in physical therapy clinics that follow the Owens Recovery Science or Delfi Portable Tourniquet System for Blood Flow Restriction protocols. The second uses a narrow, elastic pneumatic band that inflates and deflates briefly and  rhythmically across a session, never occluding arterial flow. This is the original KAATSU approach. The first is occlusive. The second modifies rather than restricts blood flow, the method that Dr. Sato spent six decades refining, and researching. KAATSU is the method that we sell, certify, and teach.

If you came across the term BFR and want to know the original concept where it came from, KAATSU is the roots of BFR. The category is not interchangeable.

What The BFR Research Shows

Across more than two decades of published literature, BFR training combined with low-load resistance exercise produces muscle hypertrophy and strength gains comparable to traditional high-load training. The mechanism is well-supported: a robust hormonal response including human growth hormone, IGF-1, vascular endothelial growth factor, and brain-derived neurotrophic factor; increased muscle protein synthesis; angiogenesis in working tissue; and improved vascular tissue elasticity. The literature on safety, when proper protocols are followed, is reassuring. Adverse events in the published record are rare and overwhelmingly tied to user error or to occlusive equipment used with heavy loads or high intensity.

It is also worth being honest about what the research does not show. BFR does not appear to remove toxins from the body. It does not clear the lymphatic system. It does not, on its own, reverse scar tissue. It is one tool among many for vascular and muscular health.  Its gentle convenience, comfortable ease-of-use, and portability not only lead to high compliance rates, but also offer advantages over pneumatic occlusive cuffs.

How To Think About BFR Before Investing in Equipment

If you are evaluating equipment, the first question to ask is whether the band is pneumatic, with an internal air bladder you can control by pressure setting, or whether it relies on a manual elastic strap. The second issue is whether the cuffs hold pressure constant or if the bands briefly, automatically, and repeatedly inflate and deflate. The third issue is whether the band manufacturer can point to peer-reviewed safety and efficacy data on its own equipment, not on the category in general. The fourth issue, frankly, is whether the company has been around for decades in dozens of countries being used by people of all ages.

We would also suggest that the term BFR is broad enough that any given product can mean very different things. The 30/15/15/15 set-rep regimen that appears in many BFR articles is not a KAATSU protocol. That regimen is a creation of the BFR market. KAATSU protocols call for three to four sets with 20-second rest intervals maximum, beginning with 30 repetitions on the first set, and decreasing naturally across subsequent sets.

Where To Go From Here

If you want to read the original 2000 paper, it is freely available ( "Effects of resistance exercise combined with moderate vascular occlusion on muscular function in humans"). If you want to read about safety considerations for clinical populations, two Nakajima papers summarize the results: "Use and safety of KAATSU training: Results of a national survey" and "Use and safety of KAATSU training: Results of a national survey in 2016".  If you want to compare equipment, we have published a side-by-side comparison page. And if you want to read about the method in Steven Munatones' own words, we maintain a long-form Q&A archive that goes back several years.

Whatever you decide, we recommend reading carefully and being patient. The work surrounding KAATSU has been around for sixty years. Spending more time understanding it well before you commit is an investment well worth your time.

Want to learn more about KAATSU and Blood Flow Restriction? Reach out to our team at info@kaatsu.com for further guidance on equipment, protocols, research, and use.