Stand tall, crunch your elbow to your knee, side abs lit.
Squeeze the side you are crunching, do not just bend over at the waist.
Crunching your elbow down while driving the same-side knee up shortens the obliques through lateral flexion, one side at a time, all from standing. Because you are upright, your core also has to stabilise you on one leg for a beat each rep, which is work a floor crunch never asks for. It suits circuits, warm-ups and anyone who wants direct oblique reps without getting on the ground.
Yes, the side you crunch works through a real contraction, and standing on one leg adds a stability demand floor crunches skip. They are lighter work than weighted oblique moves though, so treat them as volume and activation, not your only core training.
You are probably just bending sideways instead of crunching. Think elbow and hip crushing together with the side abs squeezing, pause a beat in the contraction, and slow everything down.
Finish one side, then switch. Staying on one side keeps constant tension in those obliques and makes it obvious if one side is weaker.
