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.
Get down into a plank position, squeezing your butt, with a glider under each foot, on the edge of your mat. Using your forearms, crawl forward about five steps, until your gliders hit the end of the mat, and then crawl back. Make sure to hold the plank position and keep legs straight and hips stable. Do this 3-5 times, counting forward and back as one full rep.