Relfections from the ISB Footwear Biomechanics Meeting

Recently the Footwear Biomechanics Group of the International Society of Biomechanics had its conference on the Gold Coast in Australia. I did my best to live post things as it happened but did get a bit bogged down. I did a previous post on some of the gems from the same meeting in Liverpool in 2015; but this time while there were a lot of gems and pearls, I only going to comment on three things that have stuck in my mind since the meeting. I am sure others who were at the meeting will have a different set of highlights.

Science, pseudoscience and footwear science
This was the keynote from Martyn Shorten. Given that I seem to spend so much time playing ‘whack-a-mole’ stalking pseudoscience (as soon as you whack down one, another rears its head), I always going to be interested in a presentation titled like that and this was no exception. Hopefully he will publish his presentation in full as I only want to comment on one small part of the presentation, as it did really make me laugh. Of course, Martyn was only poking fun at the fan boys. Here is a link to the abstract for those who have access.

He pointed out what we already know in that runners are generally pretty poor at self-identifying their own foot strike pattern (I blogged about that here) with ~40% of runners saying they are not heel strikers, when in reality ~95% are heel strikers. What he pointed out was that the mean touch down ankle was 16.9 degrees dorsiflexed, which is no surprise. However, if you look at the graph of the data around that 16.9 it is almost a perfect bell shaped curve. If rearfoot and midfoot/forefoot strikers were distinct groups, then there would not be a bell-shaped curve, but a double hump curve. The data did not show that, the touch-down angle (foot strike pattern) is actually a continuum and there are no groups, which does make sense. Where he got the laugh was when he pointed out the forefoot strikers are more than two standard deviations from the mean, that makes them outliers. That is worth thinking about.

Gait Analysis at Retail Increases the Risk for Running Injury
At the retail level the prescribing of running shoes frequently follows a gait analysis, so that if you are starting to nod off at a conference when you hear that this might increase the risk for a running injury, you suddenly wake up and pay attention. I posted this comment in social media at the time it was made and got quite a reaction! This paper from Tine Willems et al on Is consumer behavior towards footwear predisposing for lower extremity injuries in runners and walkers? A prospective study (link to abstract for those who have access) was what woke me up. This was based on a questionnaire of 300 runners and 280 walkers that asked a whole lot of stuff about choice, price, advertising etc. After 24 weeks, 49 (24%) had suffered an injury. A logistic regression analysis of that questionnaire data collected at baseline showed that the following were risk factors for injury:
– a gait analysis before buying footwear
– not caring for the model or closure mechanism of the shoe
– feeling very much concerned about the price quality ratio

That is what the data showed. It showed what it showed: a gait analysis before buying the footwear increased the risk for injury. One can only speculate several different putative reasons or mechanisms by which that might happen. It certainly raises questions about the decision making the process for the prescribing of footwear based on a gait analysis. I will certainly comment more later on this study when the authors publish it in full.

Subjective and biomechanical assessment of ‘ride’ during running
This one from Christopher Ka-Yin Lam, Maurice Mohr, Hendrik Enders, Sandro Nigg & Benno Nigg has been occupying my mind a lot since hearing it (link to a abstract). “Ride” is something that runners talk about a lot and there have always been issues with what do they mean by ‘ride’ when they use that term. Eg, you hear comments like “the ride of the {shoe model} is awesome“. While there are a few things about this paper that demand deeper scrutiny and will wait for the full publication, the real highlight for me was that I like the definition that they have used to try and operationalise this concept or term of ‘ride’:

ride is the feeling of the transition from heel to forefoot during the stance phase of gait

They then tried to correlate that subjective feeling that runners gave them about a running shoe with the velocity of the center of pressure. This was just a proof of concept study and looks really promising.

The whole concept of ‘ride’ has interested me for a while. Is ‘ride’ linked to running economy? If the ‘ride’ is better, is the running economy better? If the ‘ride’ is better, is the running easier and the tissues do not have to work so hard, so if the ride is better is there a less risk for injury? Can we use biomechanical variables (like the study above) to quantify ‘ride’? Can we improve the prescribing of running shoes based on how the ‘ride’ feels? What determines the ‘ride’ in a shoe? One thing I am pretty sure of is that what one runner feels from one shoe as having a good ‘ride’, another runner won’t. In other words, the experience of ‘ride’ from each particular shoe is going to be subject specific. I previously blogged about one of our studies on the systematic vs the subject specific timing of load coming off the heel across a range of different types of running shoes. It is now interesting to reflect on that study and wonder how much of that was related to the runners subject specific feeling of ‘ride’ … we did not collect that data.

There was a lot more that happened at the meeting I could write about, but they were my three highlights, in addition to catching up with so many friends and colleagues. Cool hanging out with CK again and, of course, an awesome job from Peter Milburn et al for putting the whole thing together..

As always, I go where the evidence takes me until convinced otherwise …. and we have to keep going where the evidence takes you, even if it does not confirm your preconceived biases.

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