Set-up: Establish a neutral spine, brace your core and enter a partial squat position.
Movement: Start by rotating your toes outwards, then your heels. With each rotation your stance will grow wider. Once you've reached two to three times hip width, or the limit of your well controlled mobility, reverse the movement by alternately rotating your toes and heels inwards.
Emphasis: Do not let your knees push far forward in front of your toes. Focus on engaging your adductors and glutes.
Assists: Holding onto a railing or other sturdy object can make the exercise easier.