Biomechanics and Your Feet

Biomechanics is the study of the mechanics of a living body, especially of the forces exerted by muscles and gravity on the skeletal structure. We often forget how the body aligns itself over the foot and the importance of correct alignment.
     The foot, which includes everything below the ankle, is a complicated but amazing engineering marvel. With an intricate biomechanical composition of 26 bones each, together they account for almost one-quarter the total number of bones in the entire body. There are 33 joints to make the feet flexible. About 20 muscles manage control of the foot’s movements. Tendons stretch like rubber bands between the bones and muscles so that when a muscle contracts, the tendon pulls the bone. Each foot contains more than 100 ligaments that connect bone to bone and cartilage to bone and hold the whole structure together. Nerve endings make the feet sensitive. With each step you walk or run, your feet are subjected to a force of two to three times your body weight, which makes the feet prone to injury.
     The big toe, commonly called the great toe, helps to maintain balance while the little toes function like a springboard. The three inner metatarsal bones provide rigid support while the two outer metatarsal bones, one on each side of the foot, move to adapt to uneven surfaces.
     Your feet are each supported by two arches. The transverse arch runs from side-to-side just back from the ball of the foot. This is the major weight-bearing arch of the foot. The medial longitudinal arch runs the length of the instep, flattening while standing or running and shortening when you sit or lie down, giving spring to the gait. The lateral longitudinal arch runs on the outside of the foot. Both longitudinal arches function in absorbing shock loads and balancing the body. These three arches of the foot are referred to singularly as the foot’s arch.
     With a basic understanding of the foot’s construction, it becomes increasingly important to be aware of how we affect our body’s biomechanics. At some point in training for an event, we need to try to mimic the event itself. Wear the same shoes and socks that you plan on wearing during the event. Wear the same clothes; carry the same weigh in a fannypack or backpack; even get out in the same weather. Even though we may not realize it, these factors can change our stride, work different muscles, and put pressure on different body parts—including the feet.
     The next post will explore how to avoid biomechanical problems.