Day no. 9 – Frog Exercise From Barre Leg Upper Body Lifts. Start lying on your stomach on top of a mat. With one fist on top of the other and your elbows bent, place your forehead into your top fist, pressing your arms into the floor for support. Bend your knees, flex your feet in the air, and lift your knees off the floor. Then extend your knees behind you, using the energy in your heels to press your legs away in a pulsing tempo. With every press of your heels, emphasize the slight straightening of the knees as you pulse your legs away from your butt. Think of a frog that squats down and leaps. Your knees are making a similar motion and, like a frog, your legs are suspended in air. Complete this exercise for 30 reps.