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28.01.2010

Oxygen shortage makes strength training more effective

Weight training in an oxygen deprived environment probably results in more muscle mass over time than training where there's plenty of oxygen in the air, write sports scientists from the Japan Institute of Sports Sciences in Medicine & Science in Sports & Exercise. The combination of strength training and little oxygen results in an increase in growth hormone production.

For years Japanese scientists have been studying the effects of cutting off the oxygen supply to the muscles by reducing the circulation of the blood. It's called Kaatsu. According to the studies, Kaatsu training produces a higher anabolic stimulus than normal. The effect of Kaatsu training is so great that using weights at 30 percent of your 1RM creates an anabolic hormonal stimulus that's comparable to that of a serious training at 80 percent of your 1RM.

The researchers wanted to know whether they could create a similar effect by getting their subjects to train in a room where an oxygen reducing machine had been placed. They used a Hypoxico Hyp-100, pictured in the photo above.

The 12 test subjects were healthy men aged about 30, all of whom did regular weight training. The researchers got them to do 5 sets of bench presses and 5 sets of leg presses at 70 percent of their 1RM. On one occasion the test subjects trained under normal atmospheric conditions [NR], and on one occasion in an oxygen deprived atmosphere [HR]. Under HR conditions the subjects produced more lactic acid and growth hormone, as shown below. The grey area represents the strength training.

The researchers also measured the subject' cortisol, IGF-1 and testosterone. HR or NR atmosphere, it had no effect on hormone production.

Training under low oxygen conditions may also lead to faster weight loss. At least, the effect on the stimulatory hormones adrenalin and noradrenalin would suggest this. These hormones force fat cells to release their contents into the bloodstream.

"Resistance exercise in acute systemic hypoxia caused greater accumulation of lactate, and greater response in growth hormone, adrenalin, and nor-adrenalin to a bout of resistance exercise", the researchers conclude. "Our data suggest that hypoxia is a potent factor for the enhancements of anabolic hormone response to resistance exercise."

Source:
Med Sci Sports Exerc. 2009 Dec 14. [Epub ahead of print].

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Restricted muscles grow faster 15.03.2009
Restricting blood flow makes muscles grow 14.02.2009