5 reasons running on pavement probably isn’t injurious

It seems common-sensical that running on hard surfaces is risky for overuse injuries like shin splints and plantar fasciitis. Surely harder surfaces involve more impact, more biomechanical stress, and therefore more trouble?

Like many “obvious” ideas, this one has a glaring citation needed problem. Is there any direct scientific evidence that running on hard surfaces is actually injurious? Has anyone ever gotten big groups of people to run for a long time on different surfaces, measuring injury rates in both groups (a prospective trial)? Incredibly, no: despite decades of running research, it’s still an untested idea (see this readable 2016 overview; the evidence is unchanged as of now).

So it’s not proven that hard-surface running is risky, but it’s not exactly a crazy idea either. It’s a reasonable hypothesis, and there are arguments and evidence both for and against it. In this post, I share five perspectives that cast doubt on the alleged “danger” of running on roads and sidewalks.

Hard surfaces are innocent! The case for the defence

1. Runners’ joints are in great shape. A 2018 study showed that runners probably have half the rate of knee and hip arthritis than non-runners. This generally undermines the popular idea that running is “hard on the joints,” and suggests instead that it’s actually stimulating adaptation, making joints tougher. If true (and it almost certainly is) it undermines the obviousness of hard surfaces being problematic.
2. Humans have amazing shock absorption features. For instance, when we run onto a new surface, we adjust the spring in our step after one step — by adjusting our leg stiffness. Muscle tuning is the dynamic dampening of impact vibrations with precisely timed muscle contractions. Springing is the more obvious one: we adjust the springiness of our entire body by being bendier. Harder surface? More bending! Softer surface? Less bending! So we probably cope with surface hardness quite well.
3. “Impact forces” are not strongly associated with injuries. “The evidence of the link between injury and impact related factors is either just not there or far from compelling,” writes Craig Payne on RunResearchJunkie.com, summarizing a review of studies.
4. Shoes don’t make much difference. If surface matters, then what we put between our feet and the surface probably matters too — a proxy surface — but no kind of shoe (or lack of shoe) has been clearly shown to make any important difference in injury rates. It was only in 2016 that we finally got good data on barefoot running, showing it to be quite similar to shod (different injuries, but the same overall injury rate).
5. Ignore fear-mongering claims made without evidence. “Common sense” is often suspect, and Hitchen’s razor cuts deep here: “What can be asserted without evidence can be dismissed without evidence,” and probably should be if it discourages people from participation in what is clearly a healthy activity. In other words, until we actually know, let’s err on the side of not making people scared of a risk that may not exist. A positive attitude probably matters more (see papers by Clare Ardern, like Ardern 2013).

Do not fear the pavement!

There is another side to the story, though. So what about the evidence for the prosecution? For that, and much more detail, see Is Running on Pavement Risky?