Not only is rebounding fun, N.A.S.A. says it's the best exercise devised by man. N.A.S.A. has been using rebounding to train their astronauts for years. A N.A.S.A. study found that rebounding is 68% more efficient than treadmills or other forms of exercise. N.A.S.A. also found rebounding to be helpful in rebuilding the bone mass and muscle mass that astronauts lose in the weightlessness of space. These results are implications that rebounding is beneficial for those with osteoporosis. Urban Rebounding is a low impact fat burning exercise done on a mini trampoline. Improve balance, coordination, proprioception, muscle strength and have FUN! Time flies when you are on a trampoline.