Lie on your back with both hands behind your head.
Crunch up and pull your right knee in towards your chest, extending your left leg out 6 to 12 inches off the ground.
Twist your left elbow towards your right knee, then use a pedaling motion to switch the position of your legs, twisting your right elbow in towards your left knee.
Continue the pedaling motion and crossover crunching until you have completed a set number of repetitions or a set time period. Pulling each knee in is one repetition. Doing a crunch towards each knee is one repetition.
This is a basic abdominal workout that not only challenges the abs but also incorporates the obliques and hip flexors. This move is well suited for boot camp style exercise routines or home workout routines as it requires only a mat. The situp variation burns a high number of calories due to the number of major muscles that it incorporates. Wearing ankle weights, or holding a dumbbell behind your head can make this movement harder.