Sufferfest says sprint, so I get out of the seat and go.

However, I am always wondering if I am going to hear the dreaded pop of carbon cracking. I have a standard trainer that doesn't swivel or do anything but hold my back wheel. Because of being conscious of it, I'm not cranking the bike side to side, just trying to hammer a bit.

Are my fears unwarranted? Or should my butt stay down when I "sprint"?