Altitude Training
I recall reading an article about balloonist Steve Fossett's preparation for his unpressurized flights. If I recall correctly, the article stated that he prepared by, among other things, sleeping in a 'tent' with low O2 partial pressure in order to acclimate to altitude.
I seem to recall seeing some articles about improvements in this type of training, utilizing a mask system, monitored by a pulse oximiter, etc.
Anyone have any information or experience regarding this sort of training? Either for unpressurized flight or physical performance (i.e. mountain climbing, free diving) training?