I'd like either a 1) circle/circular image, that's a bit abstract - representing both the form of the rebounder (it's round obviously), but also the feeling of no end, no limits. Maybe several circles together, like you've drawn them by hand over and over. MY FIRST CHOICE.
Or, I also like the idea of an abstract "infinity" symbol representing limitless or "boundless"
I think working w/NEGATIVE SPACE might be very cool too. ( I attached 2 examples below, #2 & #3 respectively).
Finally, a couple designers incorporated an abstract figure in motion and I really like this idea too. Again, my first choice is a circle-image as logo and emblem.
PLEASE SEE MY ATTACHMENTS. I really like the multiple circles in this first attachment "BE ALIGNED" and my other top favorites are #'s 4 & 5 and the red bird in circle in #9