Build a bulletproof core with this routine by Jamie Hale, owner of MaxCondition Training (maxcondition.com). Doing these three compound exercises as a circuit will ignite new muscle growth and boost your metabolism. Finish as many circuits as you can in 15 minutes, resting 60-90 seconds between sets.
Stand with your feet hip-width apart. Hold dumbbells in front of you, your arms bent 90° and palms facing each other. Squat until your thighs are just past parallel to the floor. As you stand back up, press the weights above your head, then bring them back to the starting position. Do 8-12 repetitions.
Holding a dumbbell in one hand, lie facedown on an incline bench and let both arms hang. Pull the dumbbell up toward your midsection as you keep your elbow close to your body, and then lower the dumbbell back to the starting position. Do 8-12 reps. Switch arms and repeat.
Lie on your back with your legs straight. Hold a dumbbell in your left hand, your arm straight above your chest. Stand up, keeping your elbow locked and the weight above you, and then lie back down as you keep holding the weight above you. Switch hands and repeat. Do 4-6 reps each side.