A new study in the Journal of Strength and Conditioning Research shows that exercises that work both the legs and the upper body target the core more than traditional abdominal exercises (in fact, a study in the same journal shows that crunches don't do much for you—besides make you more efficient at doing crunches). This full-body calorie-burning move from Montenegro works not just the abs and obliques but also the glutes, hips and shoulders.
1. With dumbbells at your side, bend into a squat, pushing your hips backward as if you were sitting in a chair. Keep your back straight and your abs engaged.
2. As you raise your hips to come to standing, press the dumbbells over your head, rotating the torso toward the right, using the side of your abdominals. This should be one fluid movement.
3. Lower the dumbbells and bend into a squat again. Repeat the shoulder press to the left side.
4. Alternate sides for 12 total reps.