What a gimmick that mask is. I also wonder about the health dangers. This is not training at altitude but depriving yourself of air. You mean going for a run is to easy for you? You can train forever with no fatigue so you need to deprive yourself of air to make it harder? Like Wes said, attention whores need to wear this with their toe shoes. Then they get into their jacked up 4 x 4 that never leaves the pavement.