Attach an ankle strap to cable machine, then to your ankle and then proceed to lie down face down on a bench facing away from the cable machine. Make sure you have sufficient tension on the cable before commencing the movement. Flex your foot towards your shin and then proceed to lift your foot towards you by flexing at the knee and exhaling as you do so. With control, lower the leg to the starting position, inhaling as you do so. Perform all reps and then repeat on the other leg.