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Issue 6

Table of Contents

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Can the appropriate footwear prevent injury in leisure time running? Evidence versus beliefs

Dr. Joe Camoratto PT, DPT

Key takeaways:
  • Certainty in the running shoe world does not exist
  • Going with a comfortable shoe is not a bad idea
  • Intelligently progressing running stimulus is a better place to spend mental energy
  • Sneaker companies are making a lot of stuff up for the sale

 

Goodness gracious do we have a lot to get into.

There is something that I have been saying, quite sarcastically for years: “Any shoe you run in is a running shoe.” Today, we evaluate this claim in a paper from 2020 that takes a critical look at almost every claim from Big Sneaker available. All the way from “run in what’s comfortable” to “should we be wearing shoes at all?”

The physical activity guidelines for Americans says that every single person in this country (and the WHO says everyone on the globe) should be getting at least 150-300 minutes of moderate intensity aerobic activity, or 75-150 minutes of vigorous intensity aerobic activity per week. In that grouping of vigorous activity (6.0 or more METs) is jogging/running. It’s certainly no surprise that running is so popular considering how accessible and easy to initiate it is. Countless patients tell me they run frequently due to being able to “just open the door and go.” If we are taking into consideration barriers to entry, running has relatively little.

It just so happens that many of those people that tell me that running is their go to are also coming in because they have a running related injury (RRI). One of the biggest risks of a running related injury is history of a running related injury. The most common one (anecdotally) is medial tibial stress syndrome, or shin splints if you’re a layperson. This is certainly not the only running related injury of course. Ankle sprains, knee pain, low back pain, hip pain just to name a few are in there as well.

RRIs are the main reason that people stop running, and there is a great reason to keep people running: those who are running because of the ease and convenience of it are unlikely to do other things that have higher barriers to entry. This is not always the case, but surely for some unbeknownst-to-me number of them. Due to the large popularity of running, the market for running accessories, mainly shoes, is enormous. When markets for physical items that involve direct to consumer sales are enormous, there is bound to be misinformation in marketing. The running market is no stranger to this. As we get more into our article for today, Can The “Appropriate” Footwear Prevent Injury in Leisure Time Running? Evidence Versus Beliefs, it will become evident how little we really know based on current literature.

First and foremost, let’s all agree that humans evolved to run on two feet. There has unfortunately been a non-zero amount of people and clinicians included that are under the impression that the spine isn’t made to be upright. Hundreds of thousands of years of walking and running upright have cemented that for us. So if you come across anyone that claims that we were really made to be on all fours, we ask them politely but firmly to leave.

One thing that we are uncertain of is what type of striking pattern we evolved to run with. Was it forefoot, mid foot or rear foot? Does it land somewhere in the middle? Does it change? This paper points out that not only are we unsure, but we also weren’t around to write down any injury data, although that would be helpful. There are two paradigms that come up in regard to running in general: First, the musculoskeletal system strives to stay in a preferred movement path for a given task. This basically means that the body will adjust to maintain homeostasis given the context. Second, the comfort filter as perceived by the running is the most critical aspect for both injury prevention and running performance. This simply insinuates, if you’re comfortable, you’re doing great. The main issue here is that we don’t really have a lot of evidence for either one of these paradigms.

Time to talk about RRIs. Injury in and of itself is quite a complex and complicated topic. One involving multiple criteria that need to occur at the same time, and sometimes a 4D chess match of semantics. For our purposes, we are going to utilize a definition of injury that goes like this: There needs to be some perceived symptom, a time away from the sport (running) and some type of tissue change. I could write an entire research review about injury, and likely will at some point, but for right now we will stick to that.

What is the main cause of RRIs? It seems to be a mismatch between capacity (of the runner) and the stimulus applied to them. The injury incidence rate of running ranged between 18.2% and 92.4% with injury occurring between 2.5 and 330 injuries per 1000 hours of training. To compare this to resistance training (2-4 injuries per 1000 hours) that’s a lot of injuries. Of those injuries, overload injuries accounted for 75-85% of them. These mainly occurred in the lower limbs, and as I mentioned previously, the biggest predictor of an RRI was a previous one.

This brings us to shoes. How? Well, because people like to point fingers at things and really the only equipment between you and the road are your shoes. What makes matters worse is that the running shoe industry (Big Sneaker) launches multiple unsubstantiated claims. To pile on even further, the scientific community does a pretty cruddy job of consistently reporting and evaluating individual shoe factors, confusing everyone.

Shoe science currently exists in fragmented pieces. It’s called the Bermuda Triangle, and it covers three pieces of shoe science, but never really the whole picture. Those pieces include studies about footwear and biomechanics, foot wear and injuries and injuries and biomechanics. “The ideal approach would be to monitor a large cohort of runners, analyzing their running technique in standard conditions as well as in their own habitual environment, and follow them over a sufficiently long period to assess their exposure to running and injuries sustained.” Why this hasn’t happened is basically because it’s a huge pain in the ass.

Time to look at what we do have. We are going to cover:

  • Shoe prescription according to foot morphology
  • Shock absorption properties
  • Foot morphology and shoe types
  • Shoe drop
  • Shoe age
  • Barefoot running and minimalist shoes

Shoe Prescription According to Foot Morphology

The article refers to this as The Shoe Shop Theory. In a nutshell, expert opinion. You roll up to a shoe store or a sporting goods store and ask the clerk, which shoe is best for me? They stick you onto some high tech machine that analyzes your foot dimensions, measures your arch (or lack thereof) and even does your laundry for you. Or the clerk eyeballs your foot and picks out some shoes that they think might fit your foot.

The shoe shop theory “relied on the assumptions that running injuries were caused by excessive external ground reaction forces and excessive foot motion. Therefore, running shoes should be designed to reduce impact forces and attenuate excessive foot pronation during stance phase.” Sounds great doesn’t it? From this theory we were blessed with three different shoe types:

  • Cushioned shoes, for those with high arches
  • Stability shoes, for those with normal foot shape, whatever that means
  • Motion control shoes, for those with excessive foot pronation

 

For most things in the medical and physical performance world, there is an unfortunate disconnect between what sounds great/makes sense and what controlled science finds. Ten years ago the US military ran 3 different trials testing out this method, randomly assigning 7203 recruits to either a group based on their foot shape like the ones listed above, or to a ground that was given a “stability shoe” no matter what their foot shape was.

Unfortunately for the shoe shop gurus, “a meta analysis combining the results from all three studies showed no difference in injury incidence rates between the 2 groups.” We can end this section with the statement, “no evidence indicates that prescribing shoes according to foot morphology reduces the injury risk.”

Onward

Shock Absorption Properties

Surely the material and shape of the sole of the shoe has some sort of effect on the foot? Well, yeah it kinda does! A popular approach is to change the hardness of the midsole, the rationale being that if external impact forces are associated with injury risk, then to mitigate the effect of running on a hard surface, the barrier should be soft. Unfortunately again “the influences of shoe cushioning on impact force characteristics were inconsistent.” This doesn’t mean that cushioning doesn’t matter, but it’s less clear than one might assume.

So if it does matter somewhat, when?

One team looked at 848 “leisure time runners” and the difference between 2 different shock absorption insoles. There was a 35% difference in the shock properties of the insoles. What they found was that there seems to be a body mass difference present.

“The stratified analysis according to body mass revealed that the effect of greater risk in hard shoes was confined to light runners. In other words, for the first time, these results indicated a protective effect of shoe cushioning, but only for light runners.”

So while there are inconsistent findings and things still need to be fleshed out, we can say that shoe cushioning may play a role in injury prevention. But still, it depends.

Foot Morphology and Shoe Types

“But Joe, didn’t we already talk about foot morphology?” – you, probably

Yeah, and we are going to talk about it again.

This time it is less the shape of the foot and more the position of the foot. Aka pronation and supination. We’ve heard it all before: “if your arch collapses, your ankle goes in, your knee caves, your hip internally rotates and your disc blows out”, or something along those lines. Foot pronation has got to be one of the most played out and over exaggerated scapegoats in the whole rehab game. I’ve even heard past bosses and clinic owners of mine blame TMJD on foot pronation. They’re out there people. Keep your head on a swivel.

Much like the other claims, there is high level conflict. We have two competing large studies showing the exact opposite things. The first states that “a relationship between a pronated foot posture and the risk of developing medial tibial stress syndrome” exists, “although the effect size was small.” On the other hand we have “a large 1 year prospective observational study on more than 900 runners that demonstrated foot pronation was not associated with injury risk.” Treacherous.

The next study that this paper reviews balances things out and seems to find a somewhat happy medium. More than 400 regular runners were allocated into a group that was given a pain of standard “neutral shoes” and the other given a pair or motion control shoes, the kind that flat footed people get from the shoe shop gurus.

“The primary analysis revealed that the group using the motion control shoes had a smaller injury risk, regardless of foot type. Equally interesting was that motion control shoes were not harmful for those with neutral or supinated feet.” Again, sample size too small to draw a definitive conclusion.

So what does this tell us? If you’re unsure, motion control shoes seem to be fine for everyone, and if the runner has pronated feet, going to something other than a motion control shoe might not be great.

Shoe Drop

Shoe drop is defined as the difference in stack height between the heel and the forefoot. Olympic lifting shoes have a huge shoe drop and minimalist shoes have a very small shoe drop. When it comes to shoe drop, the experience of the runner seems to come into play. Occasional runners (weekly running for <6 months) showed a lower risk of injury with a moderate to low shoe drop (6mm – 0mm) and regular runners had an increased risk of injury with the 0mm drop.

“Given these secondary analyses, it seems safe to recommend low drop footwear for occasional or inexperienced runners. In contract, regular runners who received low drop shoes appeared to be at greater risk than those using conventional shoes.”

Now one factor that has existed in all of these scenarios that we have yet to discuss is how were the factors being studied transitioned to these runners? Were they just thrust upon them without an acclimation period? Were they given time prior to the study to try them out and see how it went (unlikely). What can we assume might happen when taking a context that someone is adapted to, and changing it?

Shoe Age

To keep this one short and sweet, we don’t really know how long or how many miles is good. Women seem to be at a higher risk wearing shoes that were 4-6 months old and men seem to be at a lower risk wearing shoes that were 4-6 months old.

“No evidence based recommendation on shoe age for preventing injury can be made at this stage.”

Barefoot Running and Minimalist Shoes

To shoe or not to shoe?

I remember when I first learned about barefoot running, I was blown away that society was so dumb to have ever placed anything between they amazing flat things on the ends of my legs and the road. I was an avid toe shoe wearer for like a couple of years. I went through a couple of 10k races with Vibram 5 finger shoes on and it was fine. I got made fun of a lot but my feet and legs were great. One of the interesting things in this arena are the mileage trends between shod and barefoot runners. It seems that there were no differences between the proportions of runners reporting musculoskeletal injuries, but the density of injuries were more in the barefoot runners.

This is because the barefoot runners were running less weekly mileage, and so because they had less time to achieve the same amount of injuries as their covered counterparts, their injury incidence was more dense. Bone stress injuries were more prevalent during transitions from traditional to very minimalist running shoes, but this again calls into question the transition method. Despite this lingering question, the section ends with “no current evidence supports recommendations on the use of minimalist shoes in specific populations.”

So the next time someone says they can run because they can afford running shoes, feel free to slam dunk on them with this information.

What’re we left with here?

We have a ton of unknowns. We have a ton of unsubstantiated claims coming from the sneaker conglomerate to try to see you shoes that you probably don’t need. We need to look better at the progression of running with new shoes and the transitions while altering running shoe factors as that is likely a better place to spend time in – the stimulus and capacity realm.

There are a few things we can apply here as far as a take home message goes:

  • Look for comfort. Wearing a shoe that just hurts while its tied to your foot is likely not going to get you far.
  • Intelligently progress running and be cognizant of transitioning to new shoes
  • Listen to your body and alter running based on subjective feels
  • Alternate pairs of shoes so that the transition isn’t so harsh from one pair to another
  • Develop self management strategies for yourself and with your athletes

 

References:
  1. Malisoux L, Theisen D. Can the “Appropriate” Footwear Prevent Injury in Leisure-Time Running? Evidence Versus Beliefs. J Athl Train. 2020 Dec 1;55(12):1215-1223. doi: 10.4085/1062-6050-523-19. PMID: 33064799; PMCID: PMC7740063.
  2. Keogh, J.W.L., Winwood, P.W. The Epidemiology of Injuries Across the Weight-Training Sports. Sports Med 47, 479–501 (2017). https://doi.org/10.1007/s40279-016-0575-0