In a story reminiscent of the old “Kung Fu” series starring David Carradine, the KAATSU training methodology was conceived in the fall of 1966 — in a Buddhist temple.
Dr. Yoshiaki Sato, then a senior in high school, was attending a memorial service. While seated on his legs in a kneeling position, the traditional posture for such an affair, Sato began to feel his calves go numb.
“I started massaging my calf and noticed that the swelling and discomfort in my calf area was similar to the sensation I experienced after performing strenuous calf-raise exercises,” Sato said.
“I attributed this swelling sensation to decreased blood flow and theorized that this muscle swelling and altered sensation may be caused by, or associated with, reduced blood flow to the muscle.”
Sato began experimenting and soon learned that, by restricting blood flow, he could simulate a hypoxic environment.
What is a hypoxic environment, you ask? Simply put, it is an oxygen-deprived setting that occurs when blood vessels are compressed, which results from resistance training and, in the case of KAATSU, is artificially induced.
When muscles are placed under mechanical stress, anabolic hormone levels — including human growth hormone (HGH) — increase and myogenic stem cells, which are responsible for muscle fiber repair and growth, are activated. This dual reaction results in protein metabolism and allows the muscles to grow.
But here’s the exciting part: Whereas high-load resistance training has been shown to produce the greatest muscle hypertrophy, i.e. growth, KAATSU training allows similar hypertrophy to occur under much lighter loads.
Not only is this useful for those who can’t endure heavier burdens, e.g. the elderly, but it is also beneficial for folks with nagging injuries. In fact, Dr. Sato relates his own experience with the method following a serious skiing accident in 1973 that resulted in both of his legs being cast.
“Faced with the prospect of muscle atrophy, which is the natural consequence of the casting, I gambled with my health and began using KAATSU training,” Sato said.
“Shortly after implementing KAATSU training, I immediately noticed positive results, as my leg began that familiar swelling. When the sensation of tightness was felt in my leg, I would reduce the pressure. After a brief period, I would reapply the pressure.
“I repeated this ‘pressurizing and depressurizing’ procedure for two weeks.”
Upon visiting his doctor, even Sato was surprised to learn that “not only was the typical muscle atrophy prevented, but quite the opposite: the muscle had hypertrophied.”
“The doctor’s amazement indicated to me that I had established the fundamental technique for KAATSU training,” Sato concluded.
The Evolution of KAATSU Training
From those humble beginnings, the KAATSU method grew in popularity in Japan and, slowly but surely, gained a toehold in the United States and elsewhere — often under different names, including occlusion training, vascular reduction (VR) training and blood flow restriction (BFR) training.
How Blood Flow Restriction Training Is Done
KAATSU training typically requires one to lift 20-40 percent of their one-rep maximum and is generally appropriate only for the legs and arms, as other body parts don’t provide an easy way to restrict blood flow — although Dr. Jeremy Loenneke, an assistant professor of exercise science at the University of Mississippi, thinks the advantages may extend beyond just the limbs.
“The beneficial effects have primarily been noted in muscles under direct BFR (e.g. arms and legs), however, there is some data that suggests that skeletal muscle not directly affected by the cuff may also benefit,” Loenneke told Sports Illustrated.
“For example, a handful of studies have found that doing the bench press with cuffs applied to the top of the arm, increases muscle size and strength despite the chest not being under BFR. The mechanism behind this ‘indirect’ effect of BFR is not known, but may be related to the fatiguing of the triceps,” Professor Loenneke noted.
According to numerous experts, for best results, repetitions should range between 15-30, with a 30-second rest period between sets, when doing BFR training.
Another important consideration relating to blood flow restriction training is the amount of pressure one should put on the limbs. Unfortunately, this is not cut and dried — as Dr. Sato duly notes:
“Because of my personal experience with the potential health risks associated with this form of training, I decided to instruct people under the condition that they fully understand the associated potential risks associated with this method and obtained consent from each individual prior to their instruction in KAATSU training,” Sato says. “It was more difficult than I originally thought.
“My original difficulty of being able to apply the appropriate pressure to the limb had resurfaced since each individual required unique attention, which I attributed to differences not only in the age of the individual, but also in variations in the size of limbs and blood vessels, the amount of adipose tissue on their limbs, and their current muscular and physical strength,” Sato explains.
According to a 2013 study, the pressure should be a “7” on a scale of 1-10. In other words, the bands should feel tight, but without any tingling or numbness.
Also, research suggests that it’s best to err on the side of too little pressure than too much. A 2015 study showed that a perceived pressure of “4” produced similar results to a perceived pressure of “8.”
What Are the Dangers of KAATSU Training?
One of the concerns many people have about occlusion training is whether the blood flow restriction can lead to permanent muscle damage or, worse, blood clots.
“Muscle damage and blood clotting are two of the concerns that many people initially have with this type of training,” admits Loenneke.
Yet, studies suggest those concerns are generally unfounded, he contends. “Muscle damage does not appear to occur to a measurable degree with this type of exercise, probably because of the low loads used and the short duration that the partial BFR is applied [generally 5-10 minutes].
“In addition, the system responsible for blood clotting does not appear to be activated with low load resistance exercise in combination with BFR,” Loenneke says.
Still, he concedes KAATSU is not for everybody.
“Those who may be at an elevated risk for blood clots may want to be careful with this type of training,” Loenneke points out. “In addition, those who have had lymph nodes removed may not want to use BFR on the affected limb.”
Even Elite Athletes Are Seeing the Benefits of KAATSU
Although occlusion training is still a relatively new concept, recently, it’s been getting the attention of elite athletes.
Former World Cup alpine ski racer and Olympic gold medalist Bode Miller used the technique to come back from knee surgery in 2012.
“I’ve been getting a top-to-bottom workout with just KAATSU alone,” he said a few years ago. “That’s a testament to its effectiveness in terms of not just building size, but building functional effectiveness.” Miller declared.
And Miller isn’t the only one singing the praises of occlusion training.
Olympic silver medalist Todd Lodwick was preparing for the Sochi Games when he was badly injured performing a ski jump, breaking his arm, dislocating his shoulder and tearing numerous ligaments.
Typically, such an injury requires surgery and would have put an end to his Olympic hopes, so Lodwick rolled the dice and attempted to recover with merely a cast — just like Sato did four decades earlier.
Within a month, Lodwick was a U.S. flag bearer at the opening ceremonies and competing on the Nordic relay squad.
Does Occlusion Training Really Work?
Numerous studies attest to the efficacy of blood flow restriction training. A 2000 study conducted at the Yokohama City Sports Medical Center in Japan showed that test subjects doing tricep extensions at 30 percent of their one-rep maximum with blood flow restriction produced the same strength gains as those doing the same exercise at 80 percent of their one-rep max.
Another study at the same venue revealed that KAATSU training increased human growth hormone (HGH) production by 190 percent — nearly twice the increase that a previous study showed heavy resistance training produced.
In January of 2019, researchers screened 2,658 articles and 11 studies and determined the following: “Our results revealed that during both low-load training and walking, the addition of BFR elicits significantly greater improvements in muscular strength.”
Drawbacks of Blood Flow Restriction Training
The biggest downside to occlusion training is that it can be quite painful. Those who embrace the gym mantra of “no pain, no gain” understand that, as lactic acid builds up in the muscles from extreme effort, it produces a burning, aching sensation.
That sensation is magnified with KAATSU training, especially since the rep count is typically greater than what most traditional weightlifters are accustomed to.
Still, that’s no reason to pass on occlusion training. After all, to quote Lance Armstrong, “Pain is temporary. Quitting lasts forever.”