Bent knee hip raises primarily target your abdominal muscles. The exercise works both the lower and middle abs and is great for strengthening the key muscles that help build up the core. The secondary muscles targeted include the thighs and hip flexors. lie flat on the floor with your knees bent at around a 45 degree angle. Your arms should be right next to your sides, while exhaling, bring your knees in towards you as you keep them bent. using only your lower abs.

Continue this movement until your knees are just above your chest. contract your abs at the top of the movement and then slowly lower your legs while you straighten them at the same time. For increased difficulty try normal leg raises. You keep both legs straight throughout the entire movement and you raise them by only using your abs