Have you ever heard of Kaatsu training? It is a practice where you cut the blood supply to the muscle during your sets. The aim of this is that you will be able to increase strength gains and muscle growth even when training with relatively light weights.

According to an article which sports scientists from the Loughborough University in England have published in the European Journal of Applied Physiology, even stubborn calf muscles are able to gain strength more quickly if blood flow is restricted just above the knee when performing calf raises.

The researchers suggest that no matter how you do it, depriving muscles from oxygen will help them to grow quicker. This reason for growth may be caused by a number of factors. Firstly, anabolic hormone stimulation is greater when muscles are deprived of oxygen as shown in an experiment which saw athletes train in a room with less oxygen in the air; and secondly, muscle protein production is also increased when muscles are trained with less available oxygen.

Even though the muscle is exposed to relatively low levels of exertion, with blood flow restriction there is still a powerful anabolic response by the body. Researchers suggest that this type of training may be a good choice for those individuals who are unable to train heavy due to age or injury.

Blood flow restriction training will allow them to maximise results even when training with relatively light loads meaning that they can elicit muscle growth without it leading to overtraining.


The study which the sports scientists conducted saw 16 untrained women train their calf muscles 3 times per week for a 4 week period. The sports scientists cut off the blood supply to 1 calf by using a restrictive band while the other calf received normal blood supply. Half of the women trained at 50% of their 1 rep max while the other half trained at 25% of their 1 rep max.

Calves were trained by performing seated calf raises. The women did 3 sets with 1 minute rest periods between sets. The band which the women had around their knee stayed on throughout the training session. The figure below shows the difference between their 1 rep max when either training with normal blood supply and with the restriction.

After the 4 week period, the sports scientists also measured how quickly the blood circulation returned to normal after the removal of the restrictive band. The blood circulation recovered more quickly as a result of the blood flow restriction strength training.

The researchers are not 100% clear on why this occurs but perhaps the blood flow restriction training results in producing more and stronger capillaries within the muscles because of increased growth factors like that of VEGF.


Before you go out and perform blood flow restriction, be careful as it is not certain whether this is safe for everyone.

Because the veins are congested and distended, it may cause problems with normal blood flow by causing damage to the valves within the vein.


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