Correct Crunches?!

Correct Crunches?

This is the thing i dont get, why is it harder to do crunches with your arms back behind your head(not interlocking hands) than it is when you have your hands crossed on your chest. ?? What way is better?

Well, on the track team, we're told not to place our hands on our neck or the back of our head because it causes your muscles to strain. We hold our earlobes, keeping in mind "it only takes 8 sq. pounds of pressure to pull off an ear". If you don't want to do that, I would do the hands-crossed-over-the-chest thing, it just seems safer and more effecient to me. Just do whatever feels natural for you.