In response to two enquiries about back pain and trampoline.
It is very important to keep the upper torso and back as straight as possible when jumping on the trampoline.
Any curvature of the back or the torso while jumping on a trampoline will compress the spine when landing on the tarp.
To keep the back straight, wear a wide waist band to give the back more rigid support.
Of course, the best advice is to stop jumping on the trampoline, throw the trampoline away, and go row a boat.