What part of the body is used to determine who crosses the finish line first in a track running event?

Question

Specifically the Olympics, but I assume it's the same for any official event.

Answer 1

I use my hand.

Answer 2

Chest/ torso.

Answer 3

Whatever body part crosses the line first, I saw a video of the world record holder for 110m Hudrles win by sticking his head forward as he was nearing the finish line, as if he was looking into the ground

Answer 4

It's the runner's "body".... meaning the torso, not the head, hands, feet or legs.  It may seem as if the runners are leaning forward to get their head over first, but they're leaning forward to get the upper part of their torso over the line.

Answer 5

It is whatever part of your body crosses the line first.