Start with your upper back supported by a padded surface behind you (such as a bench or box) and a short band just above your knees. Place your feet hip width apart with your toes slightly turned out. Focusing the tension in your glutes, drive your hips up to full hip extension, exhaling as you do so. Make sure to keep your heels pressed firmly into the ground. Keep your chin tucked and eyeline looking forward throughout the movement. This is your start position. Maintaining full extension at your hips, drive your knees out forcefully against the band and continue to gently pulse your knees in and out, keeping the tension in your glutes. Repeat for the required amount of time.