Air bike crunches

Muscles worked

You need

How to do it

1. Lie on your back with your arms by your sides and lift your head and shoulders off the floor.
2. Raise both legs, then pedal them in the air: bring one knee in toward your chest as you extend the other leg out straight, keeping it off the floor.
3. Keep switching legs in a smooth, continuous cycle, with your lower back pressed into the floor throughout.