Crunches: Bent Knee (abs)

Crunches: Bent Knee are the classic, tried-and-true ab exercise, effective when you focus on a controlled contraction rather than momentum.

Lie on your back with your knees bent and feet flat on the floor. Curl your shoulders and upper back off the floor toward your knees, holding an isometric squeeze at the top for a beat before lowering back down with control.