NASA developed the differential air pressure technique as a way for astronauts to exercise and maintain conditioning in space. In 2012, NASA purchased the P200 model to use for pre-flight and post-flight training of International Space Station astronauts.  Alter-G now holds a patent for this technology, which employs air pressure to adjust the users body weight on the treadmill between 20% and 100% of normal weight.  We use this technology in the rehab setting to help bridge those patients who either need protected weight bearing, or need to re-train normative gait patterning.