Bear to Knee Elevated Leg Extension Begin in a tabletop position, with your hands directly under your shoulders and your knees directly under your hips. Brace (engage) your core while lifting your knees two inches off the ground, holding the bear plank position. Extend your right leg straight behind you, ensuring it's parallel to the ground. Then bring it back in, coming back to the bear plank position. Repeat with your left leg. Continue alternating for 30 to 60 seconds, followed by a 15- to 45-second rest.