Anyone tried this? I was browsing conditioning items and I found this.
Does the mask only increase the resistance to breathing or is there someway is reduces the inspired fraction of oxygen?!
If it only increase the work of breathing by increasing the resistance of air, the claims that it mimics high altitude training are totally wrong. Training in altitude doesn't increase the air resistance (actually air density is lower in altitude, but this aspect doesn't significantly affect breathing). Training in altitude increase red blood cell mass because there's less air oxygen for the same inspired volume, creating a relative deficiency.
I can't figure out how a mask could reduce the inspired fraction of oxygen, anyone know?! Other the training mask is a scam, unless you buy it to scare little girls.