Muscles worked
The reverse crunch flips the regular crunch round: your upper body stays put and your pelvis rolls up towards your ribcage. The rectus abdominis does most of the work, assisted by the obliques. Your hip flexors hold your legs in place, but with bent knees and short levers they do less than in the lying leg raise. Many people feel it low down in the stomach. It is the same muscle as in a regular crunch; the movement simply starts from the lower end.
Common mistakes
- Your hands push you up. Shoving your arms into the floor lets them do part of the job. Rest your hands flat and light, and shorten the movement if you cannot manage without them.
- You roll up onto your neck. Going too far puts the weight on your upper back and neck. Stop once your lower back has left the floor; your shoulder blades stay down.
- Your knee angle changes. Straightening your legs on the way down and pulling them in on the way up turns it into a kick. Keep your knees at the same angle, roughly a right angle, and let your pelvis make the whole movement.
Variations and alternatives
- Crunches move your upper body instead and pair well with this in one session.
- The lying leg raise uses straight legs and loads your hip flexors more.
- The hanging knee raise does the same job for your pelvis while you hang from a bar, a natural step up.
Sets and reps
Two to four sets of 10 to 20 reps work for most people, lowering slowly over two to three seconds. The range is short, so pause briefly at the top rather than rushing. The guide to sets and reps has more on dosing.
If 20 reps are too easy, lie on an incline bench with your head at the top and hold the bench behind your head. The steeper the angle, the harder it gets. This adds progressive overload without weights, and the hanging version comes next. If it causes pain in your neck or back, rather than tired abs, stop and have a doctor or physiotherapist take a look.