So, there was some guy running and stuffing things in mail boxes wearing this mask:http://www.trainingmask.com/
Would this work/benefit alpinists? Would it actually help you acclimate? My initial thought is no but I am curious to hear your thoughts. Something about oxygen volume and density are coming to mind
High altitudes are characterized by lower atmospheric pressure resulting in less oxygen per liter, cubic inch or whatever volumetric unit of measure you would like to use. The result is that your body has to work twice as hard to perform normal functions because of it is taking in less oxygen every time you inhale. The mask would simulate altitude in the sense that there is less oxygen. However, it wouldn't reflect true atmospheric pressure of say 20,000ft because then the person would have to be in a room pressurized to that altitude. It would benefit alpinists because they could train at lower altitudes that simulate oxygen levels at higher altitudes. HAPE (high altitude pulmonary edema) is caused from lack of oxygen, so this would be an adequate way to train because you could safely expose yourself to these conditions in a safer environment. On the other hand, HAPE (high altitude cerebral edema) is caused from lower atmospheric pressure resulting in the swelling of the brain and this condition could not be achieved by using the mask. I believe it would work for training because it mimic oxygen levels at that particular altitude due to the lower atmospheric pressure.
*Note* I study geology, not biology