ab exercises that aren't crunches

Photo: Courtesy of Michele Olson

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One-Knee Side Lift
Why do it: This yoga-inspired move is a variation on the side plank, which Olson found is 47 percent better at working the external obliques on the sides of your body and slightly better at toning the rectus abdominus (those muscles that make the 6-pack).

Starting position: Sideways: Lie on your right side with your right forearm on the floor, your hips and legs stacked.

How to do it: Press into floor, straightening left arm upward and lifting hips toward ceiling. For stability and balance, bend your right knee so that your shin makes contact with the ground. Hold for a count of "one Mississippi," then lower. Lift again and repeat. Complete 15 reps on each side.