1. Lay on your back on a soft workout surface with your fingertips placed lightly behind your ears, your feet planted on the floor allowing your knees to point upwards
2. As you exhale, contract your abdominal muscles to bring both your head and shoulders in towards the centre of your body
3. Aim to bring your body off the floor leading with your chest, not with your head
4. Your body should come all the way up to a point in which your abs finish their contraction
5. Slowly lower yourself back down to the starting position to complete one rep
The primary muscles used in Classic Sit Ups are the Abs.