BMJ. 1998 October 17; 317(7165): 1063–1066.
Copyright © 1998, British Medical Journal
ABC of oxygen
Oxygen at high altitude
Andrew J Peacock
Atmospheric pressure and inspired oxygen pressure fall roughly linearly with altitude to be 50% of the sea level value at 5500m and only 30% of the sea level value at 8900m (the height of the summit of Everest). A fall in inspired oxygen pressure reduces the driving pressure for gas exchange in the lungs and in turn produces a cascade of effects right down to the level of the mitochondria, the final destination of the oxygen.
As explained in this article, the changes in breathing at altitude are due to atmospheric pressure changes, not by the volume of air in each breathe. How can a mask change atmospheric pressure? The mask cannot reduce the partial pressure of oxygen. With or without a mask each breathe will contain 21% oxygen with a constant partial pressure for the given altitude.
ElevationTraining Mask is great because it regulates how much air you can breathe in, making it so that you breath less oxygen, in turn making the air thinner (due to the low oxygen intake it's similar to altitude training) . With reduced oxygen consumption the human body changes in several ways. The production of red blood cells and new capillaries (small blood vessels) increase the transfer of oxygen from the lungs to the rest of the body
If the mask can decrease the partial pressure of oxygen then their claims can be possible.
Trainingmask.com makes many claims that I find disturbing.
My personal take on the mask is that it doesn't change the partial pressure of O2, it provides resistance to airflow. I think to train breathing patterns, the mask may have some use but at a light to moderate exercise level. Which really can be accomplished by breathing through a straw, or swimming.