Crunch on your feet, twist the obliques.
Rotate your torso to bring the elbow in, don't just bend forward at the hip.
Bringing a rising knee across to meet the opposite elbow makes the obliques fold and rotate the torso at the same time, all while balancing on one leg. There is no floor to lie on and no equipment to set up, just a standing pattern that crunches the trunk diagonally in space. It suits warm-ups, home sessions, and anyone who wants rotational core work without getting down on a mat.
It trades some pure ab overload for rotation and balance work, so it is a different tool rather than a lesser one. On the floor gravity resists the crunch directly, standing you gain the oblique twist and single-leg stability.
You are yanking your elbow down instead of rotating your torso, which throws your weight off. Slow down, turn the ribs toward the rising knee, and plant the standing foot like it is bolted to the floor.
You can push the pace once the form is grooved, and it works well in circuits. Just keep the elbow meeting the knee through genuine rotation, if it turns into a jogging knee lift with flappy arms, slow back down.
