If you haven’t heard of Kaatsu training before, you’re in for a treat. While still a novelty in the West, Kaatsu training was developed in Japan five decades ago. Ka means “additional” and atsu means “pressure.” An English layman’s term for the practice is “blood flow restriction training,” and involves performing strength training exercises while restricting blood flow to the extremity being worked.
A significant benefit of the method is that you can do strength exercises using just 30 to 50 percent of the weight you’d normally use while still reaping maximum benefits. In a way, you’re trading weight for repetitions, in that you’re using less weight but doing more reps — up to 20 or 30 repetitions opposed to the 10 or 12 you might normally do.
The cuffs or bands are just tight enough to allow arterial blood flow but not venous flow. This causes lactic acid and other waste products to build up, giving you the same benefit as heavy lifting without the dangers associated with heavy weights. For this reason, it’s a great strategy for the elderly and those who are recuperating from an injury.
Compelling evidence suggests that venous blood flow restriction dramatically increases muscle growth and strength by increasing growth hormone secretion, reducing myostatin and inducing cell swelling — all while circumventing the tissue damage that can occur with traditional high-intensity weight training.
Brief History of Kaatsu Training
The origins of Kaatsu training were detailed in a previous Outdoors Online article:1
“Kaatsu came about in 1966 when 18-year-old [Dr.] Yoshiaki Sato, now a doctor, noticed the intense ache in his calves after having assumed the traditional Japanese sitting position during a typically long Buddhist ceremony. It was an ache much like the one he experienced after lifting weights — an ache he realized had to do [with] the occultation of blood circulation.
Eureka! Using himself as a test subject, Sato spent the next several years perfecting a system of blood-flow moderation using bicycle tubes, ropes and straps. He later replaced the tubes with thin computer-controlled pneumatic bands. The idea was to apply pressure around the arms and legs while lifting a light load, safely impeding the flow of blood to exercising muscles.
Slowing this flow engorges the limbs with blood, expanding capillaries, engaging muscle fibers and raising lactic acid concentration. But — and here’s part of what makes Kaatsu unique — it fools the brain into thinking it’s being put through a vigorous workout.”
It’s said blood flow restriction training can stimulate muscle growth and strength in about half the time, using about one-third of the weight, compared to standard weight training. By using much lighter weights, you’re also dramatically reducing your risk of muscle injury. In recent years, Kaatsu has caught on among professional soccer players, downhill skiers and American football players, including the Dallas Cowboys and the New England Patriots.
In the U.S., Dr. Jim Stray-Gundersen is a leading proponent and teacher of Kaatsu, earning the respect and admiration of athletes such as Olympic and World Cup ski champion Bode Miller — who credits Stray-Gundersen and the program with getting him back into world class form mere months after his back surgery — and other athletes who risked being sidelined by injuries.
Blood Flow Restriction Builds Muscle and Improves Performance
In the video above, Stray-Gundersen discusses Kaatsu and its benefits. If you’re intrigued by this technique, I highly recommend listening to the audio interview. The idea behind blood flow restriction training is to restrict the amount of venous blood flow your exercising muscle can get by tightening a cuff or band around the upper portion of the arm or leg being worked. This disrupts the homeostasis in the muscle, creating a metabolic crisis that has two primary effects:
1.A local effect — Reducing partial pressure of oxygen (Po2) and pH in the tissue stimulates protein synthesis. The cells will upregulate protein synthesis in an effort to improve homeostasis in the exercising muscle
2.A systemic effect — Your central nervous system also registers the crisis and sends out signals to compensate. Your autonomic nervous system reacts by increasing sympathetic tone, heart rate, ventilation and sweating (which is out of proportion to the actual work being done by the muscle); hormones involved in repair processes are also triggered, and human growth hormone, which facilitates protein synthesis.
Blood flow restriction also stimulates mTOR signaling2 and lowers your myostatin gene expression,3 thereby encouraging muscle growth4 (mTOR signals your cells to grow while myostatin, a protein produced by your muscle cells, inhibits myogenesis, blocking growth and differentiation).
One of the reasons blood flow restriction can compete with high-intensity weight training may be because it reduces myostatin to a greater degree than traditional high-intensity training (but with minimal muscle damage). Interestingly, muscle growth occurs both on the distal and proximal sides of the band; meaning, while you’re only restricting blood flow to your arms, your pecs are also affected and encouraged to increase in mass, in part due to the systemic hormone release.
So, in summary, blood flow restriction training is based on doing very light strength exercises (typically 30 to 50 percent of your one rep max) while venous return blood flow (the blood flow from your muscle to your heart) is being restricted or slowed, resulting in a low-effort exercise turning into “maximum exercise.” By forcing blood to remain inside your muscle longer than normal, you force more rapid muscle fatigue and muscle failure that sets into motion subsequent repair and regeneration processes.