Many people do these type of exercises all the time with a hip cocked up in the air which disengages the core and makes it very easy-which is why they do it duh.
So on any plank or renegade row type movement - keep the hips down and the head, back and butt flat and straight and you will be challenged and work your core the right way.
This video is my practice session for level 4 test exercises. Not there yet but getting better.
Master Sergeant, U.S. Army Retired
NASM Certified Personal Trainer & Weight Loss Specialist
Graduate Student In Exercise Science At Cal U.
Dempsey’s Resolution Fitness