For some reason this exercise is tough for me to keep my balance while trying to bring my knees to my chest. Is the genetic position of the sit bone a factor here? Also, my knees flail out to the side as I bring them closer to my chest. I need to slide a Perform Better band over my legs just above my knees to keep them close together.
I can hold an L-sit for 30 sec, but for some reason I suck at the Tuck-up. Which muscles are weak here? Will any supplemental exercises help?