Fiber College

Kaatsu aka Blood Flow Restriction Training

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 use just 30 to 50 percent of the weight you’d normally use while still reaping maximum benefits of resistance training. You use less weight but do more — up to 20 or 30 repetitions versus 8 or 12 in most traditional strength training programs.
Cuffs or bands are used that 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.

Scientists believe that restricting venous blood return can dramatically boost growth hormone secretion, reducing myostatin and inducing cell swelling.    Even better there is less overall tissue damage compared to traditional high intensity resistance training.

History of Blood Flow Restriction Training

The history of this type of training was detailed in an Outdoors Online Article (

“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.”

Kaatsu training can stimulate muscle growth and strength in about half the time, using about one-third of the weight, compared to regular resistance training.

How does Kaatsu Work?

The concept idea behind blood flow restriction training is to restrict blood flow in an exercising muscle/s using a band around the upper portion of the arm or leg being worked. This creates a metabolic disturbance that has local and systemic effects:

1. A reduction in the partial pressure of oxygen and increase in the acidity of the muscle tissue stimulates protein synthesis through an adaptive response to the stressor.

2. The central nervous system also senses the challenge and compensates by increasing sympathetic tone, heart rate, ventilation and sweating.   There is also an accentuated hormonal response as mentioned previously.

Kaatsu also stimulates mTOR signaling and lowers myostatin (myostation stops muscle growth!)
Unexpectedly muscle growth occurs both sides of the cuff even though blood flow is only restricted on the side farthest away from the heart.    The systemic increase in Growth Hormone also drives overall muscle growth.

How much Pressure?


It is important not to restrict blood flow too much, as this could lead to injury and fainting.
The good news is that research shows that if you use common sense the risk of using too much pressure is easy to minimize.  Your limb should not be tingling, turning red, blue or purple, and you should not lose feeling and should be able to feel your pulse in the limb.
For a great quick start guide to Kaatsu click here:
Kaatsu Training Protocol

A typical training session uses three sets 0f 20 – 30 repetitions per set. use half or less of the weight you’d normally use. Rest between sets is short with typical rest time being 30 seconds.

Could Kaatsu Cause Injury such as Deep Vein Thrombosis?

Kaatsu is NOT the same as putting a tourniquet on and if you follow proper precautions is quite safe.    The key is that Kaatsu does NOT alter arterial blood flow as described previously.    It is important to use cuff’s designed specifically for this process.
Contraindications for Kaatsu

  • Women who have had a mastectomy with or without radiation and/or an axillary node dissection should not use blood flow restriction training.
  • People in hemodialysis who have arterial venous fistulas. Avoid doing blood flow restriction on the affected limb
  • Pregnant women should not use Kaatsu training.