Pronation of the foot in running? What’s it all about?
Whenever we read an article about running the word pronation usually pops up. Most people think that pronation is a bad word like a four lettered bad word. I think the confusion is based on 2 different sources. The first is that there is a pronated foot type which just means a flatfoot deformity and the second source of confusion is the word pronation in the gait cycle or running cycle reference.
So let me try to clear some of this up for my new runner friends. The first thing one must know that some pronation is required in the running cycle during heel strike. A normal amount of pronation is required to attenuate the shock of heel contact. The problems and injuries occur in runners when there is too much pronation during the cycle. With excess pronation, the foot cannot convert to a rigid lever which is the necessary position for propulsion or take off. This conversion from pronation or (a lose bag of bones foot) to the supinated or (rigid lever foot) is delayed in the over-pronated foot and this results in abnormal muscle activity and bone irritation.
Some muscles and tendons are now working harder than they should be so they recruit other muscles which is where the term overuse injuries gets its meaning. Stress reactions and stress fractures result from the excessive muscle pulls on the bone. The more severe the pull the more likely the stress fracture occurs and vice versa.
Overuse injuries also increase in severity with the timing in which the over-pronation occurs. For example, if the over pronation occurs during propulsion it is more destructive to the foot and leg, than if the excess pronation occurs in the middle of the cycle. The reason being the abnormal forces are spread over a wider area at mid stance making propulsion delayed and sending a horrible torque through the great toe joint. So bad pronation is bad, and good pronation is helpful.