The crunch is a basic body-weight exercise that strengthens the core and hips. The crunch is effective at working the abs because it causes flexion and places stress on the rectus abdominis–also known as the six pack muscles. Correct form will allow you to maintain tension on your abs as your crunch and lower your torso.
Instructions
Lie flat on your back and place your hands behind your head. Bend your knees and firmly plant your feet on the floor. This is your starting position.
With your elbows flared, tighten your abs, and lift your shoulders and upper back off of the floor. Hold at the top for a second and then retract back down to starting position.
Trainer’s Tips
Don't pull your shoulders up with your hands. Instead, use your abs to raise off the floor.
Don't come up too high. Raise your torso just enough to get your shoulder blades off the floor.
Be sure to brace your core throughout the entire exercise.
