The reverse crunch is a simple core exercise that targets those hard-to-hit lower abs — without straining your neck and back.

Stand up straight with your hands behind your head. Lift your right knee up to your chest as you bring your left elbow down ...

This time, place your fingers on your temples so that your arms are bent out to the sides and crunch with your right elbow aiming towards your left knee. Don’t push to touch the knee ...

Bend the left knee and straighten the right leg at a 45-degree angle, while also crunching your right elbow toward your left knee. Return to start, then bend the right knee in toward your chest ...