Planks are tough. “Walking” while holding a plank is even harder—but it delivers results. That’s why Los Angeles-based trainer Astrid Swan included this exercise as part of the seven-day Best Bodies Challenge she created to help get you in your best shape ever.

Also known as the lateral plank walk, this move engages your core while also activating the muscles in your arms, shoulders and back. The key to mastering the exercise is keeping your hips facing the ground while moving side-to-side as a solid unit (no worming or wiggling)! Here’s how to do it:

Lateral Plank Walk

Start in a high plank with shoulders above wrists and abs tight. Step right foot and right hand to right side immediately following with left foot and left hand. That’s 1 rep. Do a few reps toward the right, then switch directions.

The effective toner is part of the Best Bodies Challenge, Abs and Arms Super-Sculpting Ladder workout..

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