Sometimes we do mistakes in our exercises. You should: – during the exercises plank- lower back straight and glutes pressed down, instead lower back bent over and glutes pointing up, – during lying legs lift- press down your lower back to the floor instead doing too much space between lower back and the floor, – during the cable crunch- have controled breathing, blow out the air when going down, instead having no balance in the exercise, – during in and out crunch on a bench- raise up chin and head, look up and control the breathing, instead chin and head pointed down, – during v-ups- push down the lower back to the floor, instead doing space between lower back and floor, – mistakes is weighted abs side bent.