Weighted Jefferson Curl

Same slow, vertebra-by-vertebra roll as a Jefferson curl, but holding a light dumbbell or plate in both hands out in front of you as you round down. The added weight increases the load on your spine as it flexes, so it's worth going lighter than you'd expect and building up gradually rather than loading it like a normal lift. Let your arms hang and stay relaxed, holding the weight rather than actively lifting with them — your spine curling is what's doing the work. Roll back up in the same controlled order, from your lower back to your neck, resisting the urge to pull yourself upright once the weight makes the top half of the movement harder.