Sqad I believe that you suck or blow air throughsome kind of resistance, Im still researching so bear with me but heres some more Info from the officcial site.
Jigsaw....I have been giving it some thought and have read JJ's comments on another thread.
If one has impaired lung function for some reason e.g Chronic Bronchits, Asthma, heart Failure and so on, then I would have thought that there would be some "mileage" in the contraption, but I fail to see how this would improve physical performance in an otherwise healthy person.