probably just completely in shock.
if i were either of those kids i would be fucking done with anything tramp/gymnastics related after that. just knowing that it could happen again would be terrifying
In all seriousness though, that's fucked! I didn't see it coming at all either, usually when you think of kids breaking their backs you think they land on their head, that kid stomped it on his feet but looks like the whiplash or rebound got him.