What the plantar arch is for

  • Unlike primates, humans have an upright posture and advanced cognitive abilities that enable them to adapt to different environments and conditions.
  • What enables us to have an upright posture? It appears to be the arch of the foot, or plantar arch.
  • Its function is also to make walking and running more efficient and economical.


What physically differentiates us from primates is quickly said: we walk upright. Agreed, there are many other differences: we have the ability to think in abstract terms, we have complex languages, and we live in highly articulated social structures. Physically, however, the main difference is related to the upright position we can assume, as well as the fact that we have an opposable thumb (which many primates also have) capable of more complex functions.

Surprisingly, the explanation of why and to what our ability to stand erect is due is not crystal clear, or at least not completely.
Therefore, scientists decided to formulate some hypotheses. One of which leads to a small and seemingly negligible anatomical detail: the plantar arch.

What it is, where it is and what it is for

It would seem unbelievable that an anatomical part of only a few centimeters could be of such paramount importance, and yet the observation of primates and especially of humans with a poorly pronounced plantar arch (exactly: we are talking about the so-called “flatfeet”) has made it possible to point out what importance it has.

Starting from the beginning: what is it, where is it located, and what is the purpose of the arch?
You can easily notice that we do not completely rest the sole of our foot on the ground by, for example, walking on wet sand and observing the footprint we leave: while the heel, toe and outside of the midfoot rest completely, the middle and inner part of the foot leaves no trace. That is the position of the plantar arch, that is, a taut, arched, raised part of the foot capable of very pronounced elasticity and responsible not only for our ability to stand upright but, more generally, for running efficiency.

Why it is so important

According to the hypothesis of the team of scientists from several American, Australian, Canadian and Swedish universities, its main function would be to reposition the ankle to an upright position after each step. If this did not happen, the ankle would be bent forward, making the act of walking or running less efficient. How? Involving muscles to be able to be performed and especially impractically loading the calf, which would require more energy to perform the gesture.

How did they notice? As we said, by studying the way primates and especially flat-footed individuals walk, to come to the realization that the stiffer or less pronounced the arch, the more the subject is inclined to bend forward, ultimately making it harder to walk/run. In fact, imagine walking-or, worse, running-while leaning forward and with your knees bent: you would expend much more energy, run less fast and get more tired.

In short, the development of this small and seemingly insignificant anatomical detail has a central importance in our evolution: it has made us faster, allowing us to do so with a reduced use of energy and in a more economical, that is, efficient, manner.

Because details are always important.

(Via Popular Science)


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