AIR SQUAT WITH CALF RAISE BALANCE
Begin by standing with your feet slightly more than hip- width apart. Send your hips backwards and squat down until they are below your knees.
Stand back up, and when you reach the top of your standing position, continue up on to your toes and hold for three seconds. Return to flat feet and repeat into the next squat. These balances will get your core firing more than an ordinary air squat.