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What Is Kaatsu?

Dan Harkins
Updated Jan 29, 2024
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A fairly new method of building muscle from Japan, referred to by the Japanese acronym KAATSU, involves restricting blood flow to the muscles being worked. Translated as "low intensity vascular occlusion training," KAATSU was created by a physician and professor at the University of Tokyo, who studied the practice for nearly four decades before patenting the process and promoting it to the public. Though some question the results, at least one study shows that just as much muscle mass can be gained through KAATSU than non-KAATSU workouts with more weight resistance.

UT professor Yoshiaki Sato was credited with the patent for KAATSU in 1996. The process, according to the KAATSU International University, leads to the capillaries becoming filled with pooled blood in the areas where resistance is being applied. The practice is considered an intriguing advancement for those with reduced range of motion or weak cardiovascular health.

When working the biceps, for instance, a belt similar to that used for a blood pressure test is applied just above the biceps at the shoulder. Bicep curls are then executed as normal, with the belt providing an added supply of pooled blood. For working the triceps on the back of the upper arm, the belt would be placed in the same place. Exercises involving this partial occlusion are largely confined to the extremities; however, a belt wrapped around the midsection, just above the abdomen, is a way of adding partial occlusion to an exercise like sit-ups. Wrapping a belt around the neck, however, should never be attempted.

According to a study published by the American College of Sports Medicine in 2007, this form of partial occlusion created just as much fatigue in test subjects than exercises with more weight resistance that did not use blood-flow restriction. The researches also urged further research to ensure the safety of the practice. KAATSU International University maintains that when utilized as prescribed, the practice is safe and effective for stimulating added muscular growth.

Without blood-flow resistance, fitness trainers frequently recommend three or more sets of six to 12 repetitions per set — the weight set at about 70 percent of that person's one-repetition maximum. With partial occlusion, however, the resistance should be low, between 20 and 50 percent of the one-repetition maximum. Though it was long thought that such low weight would not be sufficient for hypertrophy, or breakdown, of muscles — a needed precursor to muscle-building — KAATSU researchers have shown regular increases in strength and mass with the method.

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Dan Harkins
By Dan Harkins , Former Writer
Dan Harkins, a former military professional, brings his diverse life experiences to his writing. After earning his journalism degree, he spent more than two decades honing his craft as a writer and editor for various publications. Dan’s debut novel showcases his storytelling skills and unique perspective by drawing readers into the story’s captivating narrative.

Discussion Comments

By anon994758 — On Mar 04, 2016

@burcinc: Dr. Sato was still in the developmental stages when he was hospitalized. That is why you must have appropriate training to follow the proper safeguards.

The hockey player incident was a "Kaatsu like device" It was not Kaatsu and he also broke several safety rules in place.

By ddljohn — On Nov 28, 2011

@burcinc, @turkay1-- No one said that KAATSU is without risks. But I think that it's a safe method if you do it right. The important part is to start out easy, doing a few sets and then slowly building that up over the course of weeks.

Plus, KAATSU doesn't want to stop blood flow all together. The point is to decrease blood flow, so the belts should not be extremely tight and they are only supposed to stay on for a maximum of ten minutes. If you loose numbness or your skin looks very pale, you're supposed to stop immediately.

I think if these points are followed, KAATSU is safe and it gives great results. It's safer than some high intensity training options in my view.

By burcinc — On Nov 28, 2011

@turkay1-- Yea, it's dangerous! The guy who founded the technique almost died of it because the method created blood clots in his lung and he couldn't breathe!

I heard it can cause rhabdomyolysis too. This is where so much muscle cells are damaged that the huge amounts of muscle protein the blood messes up the kidney! A hockey player was hospitalized because he developed rhabdomyolysis after a kaatsu session just recently.

By candyquilt — On Nov 27, 2011

This sounds like a really interesting technique. It's nice to know that KAATSU does not require as much weight resistance as other forms of bodybuilding. I think that too much weight resistance too quickly is harmful because muscles are not given enough time to heal. So they end up being weakened at times rather than strengthened.

What is the maximum amount of time that is safe to do KAATSU training on an extremity?

I imagine that if the belt is left on too long, it could be a problem. I've had my blood pressure taken many times and that belt can be really tight. I remember losing feeling in my arm because of it. So there must be a risk of not getting enough blood circulation in some areas while doing the KAATSU method if it's not done correctly right?

Is a KAATSU trainer required during all training sessions to observe and intervene if necessary? Or can someone be taught the KAATSU method once which they can then practice on their own?

Dan Harkins

Dan Harkins

Former Writer

Dan Harkins, a former military professional, brings his diverse life experiences to his writing. After earning his...
Learn more
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