A non-impact exercise machine which can be used by people of all ages, requiring no special dexterity or athletic ability to perform and exerting minimal impact on the muscles and joints of the user, providing a light weight, collapsible, and affordable indoor exercise machine for simulating walking....http://www.google.fr/patents/US5746681?utm_source=gb-gplus-shareBrevet US5746681 - Walking exercise machine
