This straight-leg variation of the bicycle crunch challenges the abs even more than the traditional exercise.
- Lie on your back with both legs in the air and your head and shoulders off the ground with your hand behind your head. Lower your right leg toward the floor, and twist your upper body to the left, bringing your right elbow toward your left knee.
- Keep your abs pulled to your spine, and switch legs and twist to the right.
- Do 20 reps, alternating sides.