The perk: This upgrade also works your lats to help you stand taller and look slimmer.
Do it: Loop a resistance band around a low object (or use a cable machine) and lie on your side facing the band. Hold the handle with your top hand and get into a side plank (a). Pull the handle to your rib cage (b), pause, then slowly return to start. Keep your hips raised the entire time (so your body forms a straight line). Do 10 to 15 reps, switch sides, and repeat. Rest 60 seconds, then do two more sets.
Anti-Rotation CrunchANTI-ROTATION CRUNCH (Replaces: Crunch)
The perk: Your core will work harder to prevent rotation (which engages your obliques).
Do it: Attach a resistance band to a low object and lie next to it, holding the band in front of your chest with both hands, arms extended (a). Perform a crunch without letting your torso rotate toward the band (b). Pause, then slowly return to start. Do 15 reps, switch sides, and repeat. Rest 45 seconds, then do a set of 12 on each side. Rest again, then do a final set of 10 on each side.Eat-Healthy Goals? Start with This No-Brainer Eating Plan
The perk: It's trickier to balance on a small ball, so you'll work an even greater number of stabilizing muscles. The move also engages your hip flexors and rectus abdominis (your six-pack muscles) more effectively.
Do it: Start in a pushup position, with your feet on a medicine ball (a). Keeping your core tight and legs straight, raise your hips as high as you can to roll the ball toward your hands until your feet are on top of the ball (b). Pause, then return to start. That's one rep. Do eight to 12, then rest 45 seconds. Do a total of three sets.
VIDEO: Learn How to Do All of These Abs Moves with Perfect Form
AROUND-THE-WORLD PLANK (Replaces: Plank)
The perk: The plank is one of the best core strengtheners, but adding this extra challenge makes it even more effective at toning the muscles in your abs, back, and shoulders.
Do it: Start in a pushup position with both feet on a bench and your hands on the ground (a). Without dropping your hips, walk your hands around the bench as far as you can with good form, pivoting from your feet (b). Rest 60 seconds; repeat three times.
Moves created by Jim Smith, cofounder of Diesel Strength & Conditioning
TELL US: Do you do any abs exercises besides crunches?
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