Main Muscle Worked: Abdominals
Other Muscles Worked: None
Equipment: BodyOnly
Mechanics Type: Compound 
 
Tips: Works your lower abs. Lie on a flat bench with your legs off the end. Place your hands under your butt with your palms down. Put your legs straight out. Bend your knees, pulling your upper thighs into your midsection. Return to the starting position. You can hold a dumbbell between your legs to make it harder.