Kneel on a bench on all fours with a Smith Machine barbell racked behind you. Gripping the bench firmly with both hands, extend one leg behind you, bent at the knee at 90 degrees until the base of your foot is in contact with the barbell. This is your start position. Proceed to push your foot and the barbell up, contracting your glutes and exhaling as you do so until you reach full hip extension. Pause at the top and lower with control to the start position. Repeat for the required amount of reps (or time) and then alternate legs.