ANS - In the 1970’s rebound exercise such as rocking and bouncing was studied by NASA scientists in regard to astronauts returning to earth from low-earth orbit. After six months their autonomic nervous systems lost their capacity to stand in a gravitational field. The astronauts had to be dragged out of the space capsule horizontally because they would faint upon standing. They were experiencing a disautonomic condition which is similar to what CFS (Chronic Fatigue Syndrome) patients experience. So what did NASA determine as the most effective procedure to bring back the livelihood of the astronauts autonomic nervous systems? Well, it was to bounce and rock them.