The Jackknife Crunch is a Pilates exercise that simultaneously works the abs, obliques, and lowers back. It’s a great way to trim your waistline and build abdominal strength. To do the Jackknife Crunch:
- Lie flat on your back with your legs in the air and your hands by your sides.
- Bring your knees in towards your chest, then extend them straight out again.
- At the same time, lift your torso off the ground and curl your head and shoulders towards your knees.
- Hold for a second, then slowly lower yourself back to the starting position.