Sit on an exercise ball and roll out until your upper back rests on it; hold one dumbbell with both hands extended above your chest and lower your hips toward the floor.
Simultaneously pull the dumbbell back over your head and drive your hips up into a bridge position.
Return the dumbbell to the start above your chest while lowering your hips back down.
Continue this coordinated pullover-and-hip-extension movement for the desired reps.
Dumbbell Pullover Hip Extension on Exercise Ball · Gainzz