The idea behind the one I remember was to reduce the amount you could pull in, so forcing you to breathe harder at any given effort, thus training the efficiency of the accessory breathing muscles.
I'm well away that a portable hypoxia device would be a challenge.
The idea behind the one I remember was to reduce the amount you could pull in, so forcing you to breathe harder at any given effort, thus training the efficiency of the accessory breathing muscles.
I'm well away that a portable hypoxia device would be a challenge.