This is one of my favourite core conditioning exercises.
The key point to this exercise is to keep the abs locked to fix the hips while you raise your hand from the ground.
Generally I see people swaying too much which means that the core is not being utilised effectively or simply isn’t strong enough to perform the exercise.
This exercise can be done with Bodyweight or with the additional weight of Dumbbells. You can also add in Mountain Climbers and Press Ups etc.
The key is NOT to lift more weight, it is to keep the hips still!