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29.01.2010


Calves grow quicker if you restrict the blood supply

Strength training with relatively light weights results in a big gain in muscle strength if you cut off the blood supply to those muscle groups during your sets. It’s called Kaatsu training. Even the calf muscles, the muscle group that reacts least to training, gain strength more quickly if you restrict the blood supply just above the knee during calf-raises. This is the message of an article that sports scientists from Loughborough University in England will publish soon in the European Journal of Applied Physiology.

It doesn’t matter how you do it: if you deprive your muscles of oxygen during strength training, they’ll grow quicker. Yesterday we wrote about a study which showed that the anabolic hormone stimulus of strength training increases if athletes train in a room with less oxygen in the air. Another research approach is to restrict the blood supply to muscle groups. Human studies show that muscle protein production increases as a result of doing this.


The most interesting thing about this effect is that relatively low levels of exertion – like doing a short sprint – with Kaatsu training lead to a strong anabolic response by the body. Researchers are optimistic that Kaatsu training may help people who are no longer able to train hard, because of age or sickness. Progressive trainers and athletes are already experimenting with Kaatsu training. They hope to be able to add it to their regular training so they can enhance muscle growth without it leading to over-training.

In the article that will be published soon, the researchers got sixteen untrained women to train their calf muscles three times a week for a period of four weeks. The blood supply to one calf was cut off by a restrictive band, and the other calf received the normal blood supply. Half of the women trained at 25 percent of their 1RM. The other half trained at 50 percent of their 1RM.

The test subjects trained their calves in a sitting position. They did 3 sets and rested for one minute between sets. Each calf training session lasted 5-8 minutes, during which time the women had a band around their knee to restrict the blood supply. The figure below shows the effect of the training on the 1RM.



After 4 weeks the researchers also measured how quickly the blood circulation recovered after removing the restrictive band above the knee. The circulation returned to normal more quickly as a result of the Kaatsu training.



The researchers think that the effect on blood circulation has something to do with the mechanism that’s responsible for the effect of Kaatsu training, but so far no light has been shed on this. Perhaps Kaatsu training results in more and stronger capillaries in the muscles via growth factors like VEGF, they speculate.

There are already gyms in Japan where you can do Kaatsu training. It’s not yet clear though whether Kaatsu training is suitable for everyone. The researchers urge caution. "Concern surrounds the fact that the veins are congested and distended and this may cause problems for normal blood flow by causing damage to the valves within the vein", they write in the conclusion of their article.

Source:
Eur J Appl Physiol. [Epub ahead of print].

More:
Oxygen shortage makes strength training more effective 28.01.2010
Restricted muscles grow faster 15.03.2009
Restricting blood flow makes muscles grow 14.02.2009