The ankle is the most improtand joint for people to maintain their balance while walking. The ankle joint conforms to the contours of whatever surface you are walking on. If you are walking down a hill, the ankle will rotate to angle your foot down the slope so that you are not trying to only walk on your heel. If you are walking on the side of a hill, your ankle rotates either inwards or outwards so that your entire foot is in contact with the ground, as opposed to just teh inside or outside of your foot. This amount of adaptation means that the ankle must be strong enough to support itself so you don't sprain your ankle everytime you are walking on that hill. Over time, or with excessive use and injury, the muscles that surround the ankle can become weak or overstretched. Sprained or "rolled" ankles can cause the ligaments of the ankle to stretch out, which means that the ankle muscles are that much more important. Physical Therapists are able to use their extensive knowledge of anatomy and movement to determine what exercises would be the most beneficial in alleviating the pain and preventing further injury.