The 'crunch' has replaced the 'situp' for most purposes because of concerns about lower back injury and that situps may be less effective than crunches for abdominal strengthening, although this is not accepted by every authority. With the crunch, the lower back stays on the ground and you raise the shoulders while contracting the abdominals muscles.
Crunches take many forms including the standard supine floor crunch, reverse crunch, crunch with weights and on a fit ball, combined crunch and twist crunch. This description features the standard floor crunch.
Muscles worked: rectus abdominis (six-pack) with some activation of the external obliques (muscles at the sides of the abdomen).
Positioning the Body
- Lie on the floor face up with hands behind the head. Don’t clasp the fingers behind the head. The hands should not propel the head forward in this exercise.
- Legs are bent at approximately right angles at the knee with feet flat on the floor, shoulder width apart.
- Brace the abdominal muscles and hold a neutral spine position with a slight natural curve in the lower back (lumbar) region yet with the back firmly against the floor.
