Why Can’t Science Determine the Best Running Shoe?
Posted on January 10 2014
A few weeks ago I wrote a post on a new study published in the British Journal of Sports Medicine in which I predicted that media headlines/articles would get the interpretation of the results wrong. Well, yesterday Reuters published an article on the study titled “Switch to minimalist running shoes tied to injuries, pain.” And the first two lines of the article are:
“Advocates of trendy “minimalist” running shoes promise a more natural experience, but runners in a new study reported higher rates of injury and pain with the less structured shoes. Three months after switching from traditional running shoes to the minimalist variety, study participants had two to three times as many injuries compared to runners who stuck with traditional shoes.”
I disagree with this headline and interpretation. What did the study really show? Well, injury rates were indeed higher in the partial minimalist Nike Free 3.0, and runners in Vibram Fivefingers reported greater calf/shin pain, but the most interesting result to me, and the one that seems to keep getting overlooked in reports about this study, is that it found no significant difference in injury risk between runners who stayed in a more traditional running shoe and those who transitioned into the ultraminimal Vibram Fivefingers. Only those moving into the Nike Free experience higher injury rates. (for more on the details of this study view my post on it or this post by Blaise Dubois in which we discuss the results with the lead study author in the comments).
To be quite honest, these results surprised me. A lot.
I would have expected that transitioning from a traditionally cushioned trainer to a very minimal, barely cushioned shoe with toe pockets would have resulted in a much higher risk of injury. I even wrote an entire post on why I thought that Vibrams were risky and why I generally don’t recommend them. But the results of the BJSM study don’t support my own stance on the shoes. Runners who transitioned to them in this study were not at elevated risk of injury in any of the analyses they performed.
That calf/shin soreness was elevated in Vibrams was not a surprise at all (I’m guessing it was mostly all calf soreness, but the authors don’t break it down). Calf soreness is a typical experience for those going to minimal shoe because the calf presumably has to work harder. Would sore muscles after going to the gym lead you to say that lifting weights is a bad thing? My guess is that muscles on the front of the shin worked less, and if the runners in the study had been suffering from anterior shin splints or anterior compartment syndrome then their pain symptoms might have improved – it’s all about shifting forces around and knowing which areas of your body are most prone to injury.
As the science starts to come out on the pros/cons of barefoot and minimalist running what we are finding is that in general claims about improved performance or reduced injury risk are not being borne out. But, claims of increased injury risk in minimal shoes are not being borne out either. Last May I wrote about another study which found no difference in injury rates between traditionally and minimally shod soldiers. It was based only on an abstract from a presentation given at the American Society of Sports Medicine annual meeting, but the results are consistent with the findings of the BJSM study.
So what we are left with is that there is no strong support for a difference in injury rates between barely-there minimal shoes and more traditional shoes. People will run well in both, people will get hurt in both (but maybe the types of injuries will differ – we saw this pattern play out as shoes went from pretty minimal to pretty cushioned in the 1970’s). Science is not telling us that either is better than the other. This begs the question: Why?
In response to a Facebook update I put up on the Runblogger FB page about the Reuters article, a reader posed the following question:
“How come science can manage amazing things like heart transplants, in vitro fertilisation, Martian rovers, smartphones that can access anything in the world instantly, GPS accuracy etc – but can’t agree on what sort of shoes we should wear when running?”
My answer is quite simple. Human variation. Humans are not robots or machines built on assembly lines. We are variable, and biology is messy. For example, recent studies mapping the genome of Neanderthals and Denisovans have revealed that both species have contributed to the modern human genome, and the amount and proportion is geographically variable. For example, as reported on Ancient-Origins.net:
-About 1.5 to 2.1 percent of the DNA of all people with European ancestry can be traced to Neanderthals.
-Proportions of Neanderthal DNA are higher among Asians and Native Americans, who also have small percentages of Denisovan DNA.
-6 percent of the genome of Australian Aborigines and indigenous Papua New Guineans belong to the Denisovan species.
Based on this I’m about 2% Neanderthal, which I find really cool and may explain the giant noggin sitting atop my shoulders (which I have sadly passed on to my daughter and youngest son, they both have melon heads).
Another example – my friend Becki from The Middle Miles is a chiropractic student and she recently shared an awesome article showing how anatomical variability in the skeleton can influence how people perform squats. Check it out, the pictures are great.
So we’re genetically variable, anatomically variable, and physiologically variable. The environment can play a big role here too. Our bones, muscles, and connective tissues adapt to the stresses they experience. Thus, our anatomy is going to vary based on a wide variety of factors. Diet, past history of footwear use, past history of exercise type (Ever seen a hockey player run? Looks like they are skating. I had a client who was a ballerina when she was younger and she ran on her tippy toes.). The point again is that we are not all the same.
I could go on, but the point I want to make is that we should not expect there to be a single solution that works for all when it comes to running shoes (or form for that matter), and the science seems to be bearing that out by finding little difference when we compare injury risk between widely divergent footwear. Some people will do better in maximally cushioned shoes like Hokas, some will do better barefoot, and yes, some may need a Brooks Beast. Unfortunately we like neat and tidy messages telling us that one way is the best, but I just don’t think that’s the case here (maybe if we all grew up barefoot chasing antelope all day, but those days are long gone).
At the end of the day it’s an individual journey of finding out what works for you and your body given your genetics and environmental background. Science can’t answer the question of what is the best running shoe because the answer will vary depending on the person. Embrace human variability, we are an amazing species.