Although blood-flow restriction weight training uses light weights, it puts a lot of strain on your muscles. Sometimes too much, Norwegian physiotherapists suggest in the Clinical Journal of Sport Medicine. They describe the case of an athlete who developed such bad muscle damage after one session of blood-flow restriction weight training that he ended up in hospital.
The Norwegians refer to a 31-year-old ice hockey player who had been operated on his kneecaps 11 months earlier. They were helping the athlete to regain his strength, but didn’t want him to use heavy weights for strength training. They were worried that his cartilage and knee joints wouldn’t hold up.
So the therapists decided to to try blood-flow restriction weight training with the athlete. They restricted his upper leg muscles with a cuff and got him to do leg extensions: first a set of 40 reps with 12 kg, and then another 4 sets of 15 reps at the same weight. The man rested for 45 seconds between the sets.
Two days after the training session the man developed extreme muscle pain and was admitted to hospital. When the doctors measured the concentration of creatine kinase in his blood it was 12,400 units/litre. A count of 10,000 is usually when doctors sound the alarm. This is the level at which the amount of muscle protein released by damaged muscle cells into the blood is enough to start causing kidney damage. Doctors call this rhabdomyolysis.
The man stayed in hospital for 3 days, during which time the doctors put him on a fluid and electrolyte drip and encouraged him to drink a lot. Once his creatine kinase level started to drop the athlete was allowed to go home.
The researchers think that blood-flow restriction weight training can lead to “high metabolic muscle stress”. Even after regular strength training some beginners experience a rise in creatine kinase levels. Apparently this can also happen with blood-flow restriction weight training, even though very light weights are used. Looking back, the athlete should probably have done fewer sets, the therapists suggest. They should have built things up more slowly so that his body had more time to adjust.
The Norwegians were inspired by the Kaatsu training principles which were developped by the Japanese sports scientists Yoshiaki Sato. They read about Kaatsu, and tried the approach for themselves. Sato himself also learned that Kaatsu training is not without risk, and wrote about his experiences in The History and Future of KAATSU Training. [Int. J. Kaatsu Training Res. 2005; 1: 1-5.]
Sato discovered Kaatsu in 1966 when he had to remain kneeling during a Buddhist ceremony for so long that the blood supply to his calves was cut off. He realised that the sensation in his calves was similar to that felt after training – and so he came up with the idea of training with restricted muscles.
In 1967 Sato almost died as a result of following his own training method: “Numbness in my leg due to my reckless Kaatsu training routine became so severe that I was hospitalized”, he writes. “Up to that point I had ignored the numbness in my legs during training and continued with my training despite the discomfort. At one point, however I began experiencing an acute attack of shortness of breath. I went to the emergency room and was diagnosed with a pulmonary embolism.”
The training had led to the formation of blood clots, which blocked the blood vessels in his lungs.
Restricting the blood vessels is a fine art, Sato writes. “When too much pressure is applied, the skin may turn pale, and if exercise is continued while too much pressure is being applied, thrombosis may occur. It is quite difficult to reduce blood flow by the appropriate amount in order to achieve beneficial effects.”
Over the course of the years Sato has learned by trial and error what works and what doesn’t work for Kaatsu training. In 2003 he developed the Kaatsu Master, a set of equipment “which allows more precise pressure control and safer training instruction” [see above]. When Sato wrote his article there were 240 certified trainers working in 140 institutes in Japan who were capable of giving instruction on Kaatsu training. If you are still thinking of trying out blood-flow restriction weight training, it might be an idea to get in touch with them first.