SR Therapies

Biomechanics of the Feet 

The term biomechanics refers to how the living structures of the human body move. How well our muscles, joints, bones, and tendons work together determines how efficiently our body moves. Clearly, the complexity of the foot's structure means that its biomechanics are also very complex. The feet have to be flexible enough to absorb repeated impact and adapt  to variable walking surfaces but rigid enough to support the weight of the body and propel it forward.

As it turns out, the feet have an amazing ability to alternate between being a flexible adapter" and a "rigid lever". The major joints of the foot working together are capable of two distinct motions referred to as "pronation" and "supination". When we take a step certain joints of the foot unlock, allowing it to flex in order to absorb impact.

This is pronation. It occurs just after the heel strikes the ground and continues as the weight of the body is transferred to the front, or ball, of the foot. As the heel then starts to lift from the ground, the joints lock again to become a rigid lever pushing the body forward. This is supination. These motions occur in tenths of seconds when walking and mere hundreds of seconnds when running.

The complexity of these movements increases the potential for biomechanical  problems to develop. If your feet are too flexible and unstable, we say that you have "overpronation". Overpronation strains the bones and soft tissue of the feet and lower legs and can even strain the knee, hips and lower back in severe cases. 

If your feet are too rigid, we say you have "oversupination". Oversupination  can lead to ankle sprains and impact-induced injuries.

Overpronation is much more common than oversupination. In general, those with flat feet are the most severe  overpronaters, while those with extremely high arches are the most severe oversupinaters.

Did You Know......
At least once a week a patient will come to my clinic and proclaim that their arches have " fallen." While it is not unusual for the feet to change shape and size as we age, it is unusual for arches to fall. A condition called posterior tibial tendon dysfunction can lead to a flattening of the arch, but this condition is uncommon, typically affecting those who already have flat feet.

Reference: Great Feet For Life-Footcare and Footwear for Healthy Aging: Paul Langer, DPM