In this variation of a traditional crunch, called a cross-legged crunch, one leg is crossed over the other. Make sure to do an equal number of repetitions with each leg crossed to work the core and abdominal muscles evenly.
Assume start position as shown by laying on back and crossing your right ankle over your left knee.
Support head with hands, and crunch straight up toward legs.
Contract abs as you lift your head and shoulders off the floor.