All New (& Uninjured) Runners Should Wear Stability Shoes

We are proud to welcome this guest blog by Ian Griffiths. Ian is a Podiatrist with a Masters degree in Sports Injury. He has maintained an active interest in research, and is a manuscript reviewer for several Sports Injury and Physical Therapy journals. He has spoken on the topic of foot and ankle biomechanics internationally, and provides Sports Podiatry services to the PGA European Tour, RFU England Rugby 7’s, Surrey County Cricket Club, AFC Bournemouth and Arsenal Women FC. Enjoy the read!

One of my earliest (and popular) blogs was Choosing Running Shoes: The Evidence Behind the Recommendations. This is almost 7 years old now, and it felt like the right time to write a more up to date piece based on some recent online discussions I have read.

READ THIS PARAGRAPH FIRST:

The title here is intentionally provocative and controversial. Firstly, count to ten and take a deep breath. This blog (and remember it’s just a blog) does not necessarily reflect the way I practice. Furthermore, there are several caveats, which are listed in the text below. Additionally, let us admit that none of us have all the answers; so don’t expect me to get too involved in fruitless online arguments and discussions about this. We all have our own approaches, are all aware that more research is needed (and that research itself is not perfect), and all interpret what research there currently is through our own lens/bias (and some have financial conflicts of interest). Let’s try and use this as a springboard for discussion and growth.

Close to 100% of the assessments on runners that I perform and the subsequent management plans I suggest (running shoe recommendations being just a small part of these) are on injured runners. Let’s put aside these decisions we make based on presenting symptoms (what has been referred to as “pathology specific prescribing”) in this blog. For example, recommending an Altra shoe for an intermetatarsal neuroma or space occupying lesion of the forefoot, recommending a zero drop shoe for a posterior ankle impingement, or recommending a stability shoe with a dual density midsole for a Tibialis Posterior tenosynovitis – hopefully not too many would disagree there is reasonable rationale for these types of decisions at that moment in time as part of a wider rehabilitation strategy.

The real ‘debate’ is what recommendations we should make to completely uninjured and new runners… it is clearly far more complex, and this is the exact same predicament the running shoe stores find themselves in daily (and not a task I envy).

CAVEATS:

1. Running injury is complex and multifactorial, and will never be just about the shoe worn.
2. There are probably far greater ‘wins’ with respect to reducing injury risk than shoe selection; sensible load management and strength training to name but two.
3. We know that the mass of a running shoe will influence running economy and performance (increased mass = negative influence) but an assumption is made here that these factors are not the primary focus of new runners.
4. If we look at some of the research published in recent years, it should be clear to us why this is still such a topic of discussion and is lacking in absolutes.

So how do we synthesize all this and make sense of it? How do we use it to apply an evidence informed approach to recommending a shoe to a new and uninjured runner? It’s not easy, as the research is so varied in its conclusions that you can almost do whatever you want and find a paper to support it. So is the bold statement made in this blog title possible to support? How can one defend the suggestion that stability shoes (shoes with higher density medial midsoles) are the recommendation for all new and uninjured runners?

Looking at what is considered the most robust (and recent) RCT performed to date (Malisoux et al. 2016) they concluded that ‘motion control’ features reduced injury risk, and if you look at the shoe they used it is actually almost identical to most shoes marketed as ‘stability’ shoes nowadays. Their data also concluded that pronated feet did best in these shoes, and were also at greater risk of injury in neutral shoes. So let’s think of the ‘average’ (statistically speaking) foot that runners may have. The biggest sets of normative data we have on asymptomatic foot posture are the two papers which looked at the foot posture index [FPI] (Redmond et al. JFAR 2008 n=619, Gijon-Nogueron et al. JAPMA 2015 n=635) which interestingly agreed that the mean FPI was generally a +3/+4.

In any population the measure of something will follow a normal distribution curve, and from this we know that 68% of that population will be within one standard deviation of the mean (in this case FPI +3/4). We don’t know what this means in terms of the FPI likert scale, but we can conclude that it probably means the -12 and +12 feet are going to be seen much more rarely and on the whole we will probably be seeing more ‘pronated’ feet (as defined by the FPI) than anything else. If we accept the findings of the 2016 RCT then we are simply playing sensible odds by suggesting stability shoes to all (but of course won’t be right all of the time).

At this point it is quite reasonable to call me out for making decisions based on one paper, as this sort of cherry picking is inappropriate. So what about the much discussed Knapik 2010 research which was key in really starting to get people to think that matching shoes to foot types was no longer appropriate; or as we flippantly refer to it, the “death of the wet foot test”.  Let’s take a look at what they did: they actually published 3 different papers with identical methodology across three different military populations prior to this, and then grouped these results for their 2010 paper. They randomized people into one of two groups. One group were just given a stability shoe indiscriminately (with no regard for their ‘foot type’). The other were assigned a shoe category based upon their ‘foot type’ as the historical norm has been to. They were then followed over their basic military training (the fact this work is prospective one of its strengths) and it was found that there was no difference in injury risk between the two groups. The conclusion was therefore made that the way we assign shoes based on foot type was inappropriate as assigning shoes in this way did not reduce injury risk.

BUT, what happens if we look at these data in a different way… Rather than focus on the experimental group who were assigned specific shoes and discuss that their injury risk was not reduced, what if we focus on the control group and consider that regardless of their foot type they were all given stability shoes and they did not appear to have an increased injury risk??

Does this potentially further support the approach of stability shoes for all? Malisoux showed us it will reduce their injury risk, and Knapik showed us it won’t make them likely to be any more injured – win-win? Even better if they are ‘pronated’ foot types, (which statistically they are potentially more likely to be). Remember this is a new runner who is not injured and we are trying to use some of the evidence to inform us of how to ‘play the odds’.

There is no denying the theories of the team at the University of Calgary regarding comfort have gathered significant support.  So much so that many now proffer the opinion that comfort is king and as long as a shoe is comfortable then it is appropriate. This seems too simple a solution for what is clearly not a simple consideration, and we need to be mindful that whilst it is a good theory with some evidence it certainly has less evidence than it probably should have to be applied so freely as it has been in recent times. However, it should certainly be considered when choosing shoes.

And finally, the research team at the Luxembourg Institute of Health (who in my opinion have been publishing some of the best work in this field for several years now) suggested that variation is sensible. The use of different shoes (and more than one pair in rotation concurrently) has been suggested to reduce running injury risk by almost 40%.

So, there rests the case for the defense of the controversial title.

If someone is brand new to running, has no injury (or history of injury), cares little about their performance/times (initially at least), is applying good principles of load management, and is dedicating some time to strength training, then perhaps to simply play the odds they should buy two pairs of different stability shoes which they personally find very comfortable.

Does this mean they won’t get a running related injury? No.

Does this mean this is a life sentence and they should always be in these shoes? Of course not.

Is this a way evidence informed recommendations could be made based on what we currently know? Maybe.