Hamstring stretch you'll feel for days.
Hinge at the hips with a flat back, the dumbbells stay close to your legs.
The dumbbell RDL loads the hamstrings in their stretched position, the spot where muscle actually gets built, by pushing the hips back while the dumbbells slide down the front of your legs. The glutes assist by driving your hips forward to finish each rep, but the deep stretch on the way down is the money. With a dumbbell in each hand you can keep the load tight against your legs, making it a cleaner hinge to learn than the barbell version.
Until you feel a strong hamstring stretch with a flat back, usually around mid shin. The rep ends where your back wants to round, not at a set depth.
The dumbbells are drifting away from your legs or you're bending your knees too much and turning it into a squat. Keep the weights brushing your thighs and shins, push your hips back, and keep the knee bend slight and fixed.
RDLs start standing and never touch the floor, keeping constant tension on the hamstrings through the hinge. Regular deadlifts start from a dead stop on the floor and use more knee bend and more total muscle.
