Yea I've found the stretching and strength training for acrobatics has helped my back alot. It was my coccyx I injured. I come from a dance, gymnastics, baton twirling background so I feel more comfortable with XMA and bo tricks. In training so far I've never had problems with my back doing acrobatics, sometimes a little aching, but I've had problems after taking a kick to lower back or backside, or if a take a drop to the floor. This is what I'd be worried about with sparring at mo, as this was only light contact, so if it was full contact......