First, you need to lay down on the floor with extended arms behind your head. Your feet need to be together, and your toes pointed toward the ceiling. Next, start lifting your legs up and at the same time raises your upper body off the floor and reaches for your toes. Squeeze your abdominal muscles and hold the position for several seconds. Then bring your body back to the starting position.
Super Stability Ball Plank:
Rest your forearms on a stability ball and extend your legs to rest your feet on another ball behind you. Hold here for as long as you can — it won’t be long! — before bringing your feet and knees back to the ground. Perform this exercise close to the beginning of your workout, before your abdominals become fatigued.
V-Up to Pressdown
6. Hamstring Curl-Ins
Source: Gym Guider