Shown here at two different paces, each with the fact-check of the knees actually making contact with the elbows in each rep.

Not, knees-to-triceps, or knees-to-thin-air.

And no butterfly, caterpillar, or anything else;

Sit-ups are to build strength and improve position for use in other applications. If we are constantly trying to outsmart their function, they’ll do neither.