If you want a stronger core, steal a lesson from kindergarteners: Practice your ABCs.

The Alphabet Band Belly Press requires you to draw the letters A to Z in front of your chest with an anchored resistance band. "It's tougher than a lot of abdominal exercises because your midsection must resist two sources of instability," says Tony Gentilcore, C.S.C.S., co-founder of Cressey Performance in Hudson, Massachusetts, who performs the move in the video below.

First, your core muscles have to fight to remain facing forward as the band pulls you toward the side. Then your core has to work even harder to stay completely still as you jerk the band around to draw the letters with straight arms. (Reveal the abs you never knew you had with the 6 Moves for a Six-Pack .)

You'll work every single muscle in your midsection, especially your erector spinae, the bundle of muscles surrounding your spine, and your obliques, the muscles that run along the sides of your core, explains Gentilcore. Your shoulders will also get hammered as you move your arms.

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TRY IT: Loop a resistance band at chest height around a pole, threading one end through the other one so it’s secure. That’s the anchor point. Stand with the anchor to your left, clasping the band with both hands and holding it in front of your chest with straight arms. Now step away from the pole until you feel tension through the band trying to rotate your torso toward the anchor. Then stop, and stand with your feet hip-width apart and your knees slightly bent. This is your starting position.

Without rotating your torso or bending your arms, sketch out 6-inch letters in a controlled, even tempo. Breathe the entire time. Repeat with your right side facing the anchor.

MAKE IT HARDER: Increase the challenge by bringing your feet closer together, drawing larger letters, or doing both at the same time.

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