Lie on your back with your knees bent and feet flat on the floor, and stretch both arms straight back behind your head. Keeping the arms extended in line with your ears, crunch up - lifting your head, shoulders and arms off the floor as one long unit - then lower back down with control. The straight arms lengthen the lever your abs have to lift, which turns an ordinary crunch into a noticeably longer conversation with your midsection. The range stays small; the reach stays long.

Works: abs and obliques, shoulders

Breathing: Exhale as you crunch up, inhale as you lower back down.

Common Mistakes: Swinging the arms forward to build momentum instead of keeping them by the ears, pulling the chin to the chest and straining the neck, and lifting into a full sit-up instead of a controlled crunch.

Make Easier: Cross your arms over your chest and crunch without the long lever, or reduce the lift to just clearing the shoulder blades off the floor.

Make Harder: Add a 2-count hold at the top of every crunch, or slow the lowering phase to a 3-count.