Activate your abdominal muscles with this trunk curl exercise.

Trunk Curl

Lie on your back with your knees bent at 90 degrees, feet resting on the floor. While keeping your heels planted on the floor, lift your toes to dorsiflex your ankle. Push with your quadriceps (front of thigh) as if you were trying to slide yourself headword. Simultaneously perform a very slight curl to lift both shoulder blades off of the floor. Do not curl so far that you lift your lower spine from the floor. Hold 5 seconds and repeat 3 sets of 10 repetitions daily, or as directed.