Hang the feet, raise against the swing.
Control the straps, any swing means your core lost the fight, slow it down.
Raising your legs with feet hanging in low-set cradles means your core is doing two jobs, curling the load up toward your chest and killing the pendulum swing the straps generate on every rep. Unlike a hanging or lying raise, the anchor point actively punishes momentum, any cheat becomes a visible swing you then have to fight. It earns a spot as lower-ab work with built-in honesty, the straps telling on you the instant your core stops controlling the rep.
The straps move and the floor does not. Suspended feet mean any momentum turns into swing, so your core has to lift and stabilise on every rep instead of just lifting.
Slow everything down, especially the lowering. Take two or three seconds down, pause at the bottom until the straps are dead still, then raise again.
Low, as the setup describes, so your feet sit in them from a plank or hanging position. Setting them too high changes the angle and takes tension off the abs.
