Get into an extended arm plank, propped up on your hands with hands directly beneath your shoulders, feet hip-width apart. Press down on the gliders and slowly pull the knees in so they come about 4 inches in front of your hips. Then, push back to starting plank position, keeping the core tight the entire time, drawing the navel in. Do for 30-45 seconds, or 10-15 reps. You should be moving very slowly to get the most out of each move, Stokes says.
One-Legged Mountain Climber
Start in a plank position with your right knee pulled into your chest. Keep the right knee completely stable so you have a constant contraction on that side. Then, slide the left knee in and back, maintaining the height of your hips. Do 10-15, then switch and do the same on the other side.
In this move, your abdominal wall is contracted on one side by holding the knee in tight and the other side is more active so both sides are working. “They’re hard,” Stokes admits. “It’s more about the quality of your movement than necessarily the quantity,” so start out with less if that’s what it takes to do them correctly.