The aim is to allow your body to be in a position of least strain on supporting muscles and ligaments during any movement or weight-bearing activities. This applies to whether you are standing, walking, sitting or lying, as well as running, jumping or doing any other activities.
Keeping the muscles, bones and joints in the correct alignment so that muscles are being used properly and to their maximum efficiency, means not only more power and control; it also minimizes the possibility of headaches and back pain in general.