These anotomical planes are used to describe movements of segments of the body such as in gymnastics or sports techniques like bowling a ball or throwing a javelin. These planes of movement are not only for analytical purposes. There is greater significance.
The straight ahead and vertical ‘sagital plane’ is the plane of movement of the joints of the lower limb in locomotion: running, walking and cycling. The knees are functionally a hinge joint and must be aligned in this straight ahead plane. Although capable of movement in other planes, the ankle and hip joints must function in this alignment during walking and running. Any incorrect foot function causes forceful changes to lower limb joint and muscle alignment. This can cause injury or wear to joints and tearing to muscles, tendons or attachments.