Kaatsu: Low Weight Workouts For High Intensity Results?

Kaatsu is a controverse training method surfacing every other year as the one to go for for extra muscle growth. Can it work and is it safe?

Squeeze Me Baby One More Time

To stimulate muscle growth your muscles need incentive to grow. And that incentive comes via using weights that push the muscles to the limit.

It’s the mantra every workout program focused on increasing muscle mass is based upon and mountains of reliable research back it.

But twenty years ago Japanese researcher Yoshiaki Sato patented a very different method. He says you only have to put a tourniquet on your limb and then use a weight no heavier than joggers use as ankle weights. This, Sato claims, gets you the same effect as with heavy weights.

Blood Flow Restriction Training

He called it “blood flow restriction” or “Kaatsu” training (Japanese for “extra pressure”). And indeed, a number of studies found that it works:

• A 2000 study used blood flow restriction training on older women and found it gave them as much hypertrophy as regular weight training
• In a 2002 study, 17 fully trained rugby players experienced strength increases they were unlikely to reach with regular workouts
• A 2005 study recorded that Kaatsu increased levels of several hormones important for muscle growth
• A 2006 national survey in Japan stated that Kaatsu centers were highly satisfied with the training method

All this led to increasing popularity of BFR or “Kaatsu.” T-Nation tells readers it can “really ramp up your muscular gains”  and bodybuilding.com encourages theirs to “try this cutting-edge training technique.”

Yet there are some important caveats.

Blood Clots And Embolism

The biggest is thrombosis – blood clots that block blood flow in a vessel. In really bad cases the clot loosens, travels toward the heart and seals off a major vessel. The result is a stroke or “pulmonary embolism” and death turning into a realistic possibility.

Sato himself experienced this (PDF) when he started experimenting with restricting blood flow in the 1960s:

Numbness in my leg due to my reckless Kaatsu training routine became so severe that I was hospitalized. Up to that point I had ignored the numbness in my legs during training and continued with my training despite the discomfort. At one point, however, I began experiencing an acute attack of shortness of breath. I went to the emergency room and was diagnosed with a pulmonary embolism.

In the few cases where professional athletes experimented with blood flow restriction training, exact vein location was established through ultrasound, doctors applied the tourniquets and monitored participants. That’s not something you can do at the gym or at home.

The Tendons And The Bones

During normal weight training, tendons, bones and joints adapt to the increasing loads. Doctors, for example, encourage women with osteoporosis (degeneration of bone structure) to do resistance training. It makes the bones stronger because more minerals end up in them.

Does similar happen when you use BFR? Or will you end up with an 18 inch biceps on an arm bone build for 13 inches? So far nobody researched this. The idea that one day your super biceps breaks your arm when handling a heavy weight is a possibility with BFR.

The Studies Themselves

Last but not least, it pays to have a look at who conducted the studies finding positive effects of BFR training. Scroll back up, click the links and look at the authors: all of them include Dr. Sato.

There are some independent studies reporting positive effects of BFR, but in general aren’t as enthusiastic as those where Dr. Sato participated. A recent one mentions it as useful only in addition to regular strength training.

I Wouldn’t Do Kaatsu

I pride myself of having some pretty solid knowledge about human physiology, but I wouldn’t do this. The chance of putting the tourniquet in the wrong place or applying the wrong pressure is too big. There’s also the inconvenience of no established long-term effects and little independent research.

Especially if you are just starting out I advise you to follow my lead. A basic workout without weights gets you where you want to be without risking medical adventures.

Picture courtesy of the US Navy.