If you’re looking to improve your core strength (if not- why?) then get some hollow holds/rocks incorporated into your regime.
Since adding these in to my training program as part of my warmup I’ve seen a rapid increase in strength and stability during my compound lifts.
These hollow hold variations go from difficult to easy. It’s essential that you maintain a “dish-like” shape, meaning lower back down and shoulders off the floor (think forehead to knees constantly). Getting this right can be tricky so ensure you can feel the difference between your abs contracting and your lower back contracting, as soon as you feel that lower back take over then it’s time to regress the move.