A mini-trampoline is possibly the most effective exercise, especially because of the effect rebounding has on the lymph in the body. Just as the astronauts experience while floating in space, your body is in a state of weightlessness at the top of the bounce. The rebounder subjects the body to gravitational pulls ranging from zero, at the top of each bounce, to 2 - 3 times the force of gravity at the bottom, depending on how high the person is rebounding. Unlike jogging on hard surfaces which puts extreme stress on certain joints such as the ankles and knees eventually damaging them, rebounding affects every joint and cell in the body equally.