exercise demo: core

Here is the basic crunch.  Lay down and pull your belly button to your spine so that your lower back is flat on the floor.  Knees are bent, feet hip width apart and close to your butt.  Hands are behind the head, or fingertips at temples.  Keep your chin off your chest and your elbows back.  Use your core to lift your chest,  keeping your neck neutral.  Look between your knees and exhale on the exertion.

The standing crunch is a good one for people who don't want to lay down or are scared of pulling on their neck.  Stand with feet hip-width apart and fingertips at temples.  Neck is neutral.  Each time you bring your knee up, pull your belly in to contract your abdominals.