On the back?

[sparkon16]

I have heard repeatedly that turning a crocodilian
on its back will relax it so it does not struggle
a lot. My first question is, is this true? and my
second is can it be harmful to them. The reason I
ask is because when i do my monthly measuring and such there is one that just goes nuts when i try to measure her.
Any help would be greatly appreciated!

Deuce

PS Pics are coming soon!