Explain why sit-ups more difficult to do if your hands are placed behind your head instead of at your side?

Question

Explain why sit-ups more difficult to do if your hands are placed behind your head instead of at your side?

Answer 1

Definitely harder!  Think of your torso as a lever (a third-class lever), with the fulcrum being your hips.  When you put your hands behind your head, you move more weight out to the end of the lever, where it is hard to lift.  When your arms are at your side, their weight is closer to the fulcrum.

Answer 2

i think the main reason people put their hands beind their head is to support your neck, not because they're supposed to be harder

if you do a lot of situps eventually your abs get strong and when you do them, your neck hurts more than your abs