This is a picture of Laurel, Courtney, and I messing around at our friend's seventeenth bday party. We are all in different positions and balancing on one foot. This requires our center of gravity to be directly underneath us because if it is outside of the area below us, we would fall over. The more unequally distributed your mass is, the easier it is balance. Therefore the move that courtney is doing moves her CM further away from her leg on the ground. Also, we push against the ground as the ground pushes us back. This is the law of equal and opposite force. If you are actually doing these positions you would realize that you must continually push and grip your toes onto the ground.