We’ve recently been doing some work to try and understand the transition between late swing and early stance to try and provide a better evidence base for my Why we walk the way we do video series. We’d been meaning to focus on late swing to start off with but some apparent artefacts in the data compelled us to look at what was happening in early stance.
After quite a lot of head scratching we found out that the artefact (in how markers on the medial, posterior, and lateral calcaneus move) can be explained quite easily if the calcaneus rolls forward in the first 50ms or so of stance (and takes the rest of the foot with it). This makes quite a lot of sense as the foot is rotating quite fast (approx. 200°/s) immediately before foot contact and we know that the foot is lowered to the floor over approximately this period. When I went and looked at a few x-rays this seems to relate very well to the functional anatomy of the calcaneus which has an almost circular posterior-distal aspect in the sagittal plane (red quarter circle in animation below). A recent paper on the anatomy of the heel pad confirms that it too wraps around onto the posterior aspect of the calcaneus which would allow cushioning of the calcaneus throughout any such rolling motion (blue quarter circle in animation below). I’ve not seen this mechanism described in exactly this way before but it is, of course, very similar to the Perry’s first rocker of stance.
We’re just about to submit the paper and I don’t want to write too much about it before it is fully peer reviewed but the results have made me to wonder why on earth we wear heels. Placing a heel of rectangular cross section under the calcaneus would pretty much destroy the potential for this rolling mechanism that the calcaneus appears to have evolved for. So why do we wear them?
It turns out that heels as an integral component of shoes are a relatively recent invention. As far as I can gather for most of history (and in most places on the globe) shoes had flat (no) heels (see pictures below).
Heels first started to appear on riding boots in Europe in the 16th Century. Their role was not to help with walking but to retain the boot in the stirrup (and possibly to provide an anchor for spurs). Later on in the century heels to started be incorporated in shoes worn at court particularly by rulers of short stature such as Queen Elizabeth I in England and Louis XIV in France (see picture below).
Once the monarch had adopted the practice of course it spread rapidly amongst the courtiers. For a large part of the 17th century relatively high heels were popular amongst both male and female members of the aristocracy. There were even rules in France restricting the wearing of coloured heels to particular ranks within the aristocracy. During this period heels were essentially an indication of wealth and status and in English the term “well-heeled” is now used to refer to someone who is wealthy rather than someone who wears a particular style of footwear. During the French revolution there was a reaction against wearing heels as they were associated with the decadence of the pre-revolution court. Through much of the first half of the 19th Century heels were a comparative rarity. High heels never did take off for again men but returned in the mid-19th century for women particularly in Paris and New York
It is much less clear when the modern low heel came to be adopted as an integral part of the shoe for the ordinary (poor) people nor what its purpose is. Looking at the pictures on various web-sites suggests that the practice probably became common in the mid 18th century. There is some suggestion that most of the wear on a shoe occurs under the calcaneus and that incorporation of a heel reinforces the sole in this area and can also be easily replaced if that wear becomes excessive. It wasn’t however until the mid 19th century that shoemaking started to become mechanised and modern footwear started to become affordable. Since this time the classic western male shoe has evolved very little. Almost all shoes these days have a heel even though materials are available which wear very little and shoe repair is becoming a rarer and rarer procedure.
Which all tends to make me think that in the modern world there isn’t any particular reason for heeled shoes and I wonder if we’d be better off without them. (Of course I could talk start talking about minimal shoes for running or negative here but that is a completely different subject).
Note: I’ve been quite dependent on a number of different web-sites for this information. It’s very difficult to determine quite how reliable those sites are but there does seem to be a general consensus on the salient points.