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Is Running on Pavement Risky?

Hard-surface running may be risk factor for running injuries like patellofemoral pain, IT band syndrome, shin splints, and plantar fasciitis

updated
by Paul Ingraham, Vancouver, Canadabio
I am a science writer and a former Registered Massage Therapist with a decade of experience treating tough pain cases. I was the Assistant Editor of ScienceBasedMedicine.org for several years. I’ve written hundreds of articles and several books, and I’m known for readable but heavily referenced analysis, with a touch of sass. I am a runner and ultimate player. • more about memore about PainScience.com

The body is an all-terrain vehicle, born to run two million years before roads,1 and so maybe we suffer when we run for a long time on asphalt or concrete. Although running is an extremely healthy sport overall, and not as hard on the body as most people assume, running injuries are still extremely common and frustrating, and the risk factors for these injuries remain mysterious. Could it be the roads? Is it insane to do exactly the same thing over and over again with your anatomy and expect to get away with it?2 It seems almost obvious, but no one actually knows. There’s a surprising lack of hard facts about the role of hard surfaces — and the scientific evidence we do have is quite surprising.

Although most runners fear that the rigidity of concrete or ashpalt, the problem might actually be the continuity of the surface, the unrelenting same-ness of pavement. But there’s even less evidence about that possibility.

Important safety issue: for people with joints that may be unstable from previous injuries (ligament tears mostly), running on uneven or unstable surfaces (trails especially) may be the greater of evils. The evil-ness of roads is an unknown, but there’s no question that it’s all-too-easy to sprain an ankle on a trail run.

Citation badly needed! Are roads really risky?

It seems common-sensical that running on hard surfaces is risky. Surely harder surfaces involve more impact, more biomechanical stress? Unfortunately, that “obvious” idea 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: it’s actually a completely untested idea.3

It’s not like it’s crazy to think that hard surface running could be risky. It’s a perfectly reasonable hypothesis, and there are arguments and evidence both for and against it.

Hard surfaces are innocent! The case for the defense

Here are some of the clues and arguments that cast some doubt on the “danger” of running on roads and sidewalks:

  1. Runners’ joints are in good shape. A 2013 study showed that runners probably get less knee and hip arthritis than non-runners.4 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 that’s true, that undermines the obviousness of hard surfaces being a problem.
  2. Humans adapt to new surfaces fast. In fact, when we run onto a new surface, we adjust the spring in our step on the first step — by adjusting our leg stiffness.5 We dynamically adjust our shock absorption. Cool! If we’re that good at adjusting, it suggests that surface hardness might not have a huge effect on us.
  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 the significance of a review of studies.6
  4. Shoes don’t make much difference. If surface matters, then what we put between our feet and the surface probably matters — a proxy surface — but no kind of shoe, or lack of shoe, has ever been proven to make an important difference in injury rates. It was only in 2016 that we finally got good data on barefoot running compared to shod, and they were quite similar — different injuries, but the same overall rate injury rate.7
  5. Ignore 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 dismissed if it’s fear-mongering and 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.

What can be asserted without evidence can be dismissed without evidence.

Christopher Hitchens, paraphrasing the Latin proverb “Quod gratis asseritur, gratis negatur” (What is freely asserted is freely deserted), in a 2003 Slate article

On the other hand…

Hard surfaces are guilty! The case for the prosecution

The science cited above is just about the only science that clearly casts doubt on the dangers of running on roads, and none of it is actually direct evidence.

  1. Maybe trails are even better. Just because runners’ joints are in good shape — and they are, and that’s cool — does not mean they would not be in even better shape if they ran off-road. While the evidence on arthritis can tell us that road running clearly isn’t wrecking people, it is simply mute on the difference between harder and softer surfaces. Injury and arthritis are not imaginary; although bodies thrive by adapting to manageable loads, they do struggle to adapt and fail if the load is excessive. For all we know, off-road running might be the loading sweet spot for most runners.
  2. Shock absorpotion probably isn’t “free.” Nor am I convinced that just because we are good at adjusting to surfaces and changing how we absorb shock means that there are no consequences. I have no doubt it helps, but how much? When I hike down a mountain, I’m sure my legs very cleverly do everything possible to compensate for the stresses of taking thousands of steep steps downwards, but steep descents are still holy hell on my knees, and adding extra protection in the form of walking poles definitely helps.8 Clearly there are limits to our ability to shock absorb.
  3. The impact evidence is just not direct enough. Studies showing a weak link between injuries and impact forces are the closest to being relevant to the question, but they are nowhere near as relevant as actually comparing the results of running on different surfaces. They are unable to answer the scientific question here — they can only be “suggestive.” Nevertheless, I will look at this evidence in more detail below. Plus, see the next point.
  4. Actually, barefoot running is a problem. The best evidence on barefoot running and injuries actually supports (or is consistent with) the original common-sense notion that impact is a problem and the cushioning of running shoes actually does meaningfully protect us from it.9
  5. Erring on the side of caution is reasonable. Erring on the side of not worrying sounds great to me — I want to champion everyone’s peace of mind — but there’s an obvious rebuttal. In the absence of evidence, how about erring on the side of caution? It would be ridiculous to advise total abstinence from the road — that would be fear-mongering nonsense. But minimizing it? That just seems like a good use of the precautionary principle… based on a risk that’s plausible.

My conclusions on the risk question for now

The jury on this topic is definitely out, and it’s going to stay out for a long time. Having weighed all the arguments and evidence rather thoroughly, here is my opinion for now:

And so the rest of the article reads like I’ve ruled against hard surface running — which I had, when I originally wrote it. 😉 It will get more balanced and nuanced as I continue a wave of major revisions in early 2017.

More impact science

Coming soon! But, in a nutshell, it’s actually amazing how little impact forces seem to have to do with injury. For example, Zadpoor et al found that ground reaction forces (how hard you hit the ground) have no correlation with stress fractures, and vertical loading rates (how fast you hit the ground) are only slightly correlated.10 That’s pretty surprising for what seems like the most impact-related running injury.

More on this impactful topic by the end of January 2017.

Lack of variety in running surface

Most recreational runners are running on sidewalks and paved paths. Any sunny morning, you can see hundreds of them on the seawall in downtown Vancouver, where I live. They never touch the grass or the sand. A hard, constant surface feels like the path of least resistance. But on an unvarying surface, your body is subjected to almost exactly the same forces with every strike of the foot. Not only is the stress of impact exaggerated by the hard surface, but it is also repeated excessively because the mechanics of every step are exactly the same.

Worse still, the body is given little chance to adapt to any other stresses. Thus same-surface and hard-surface runners tend to become strong in one way, but weak in others — and therefore perhaps vulnerable to injury.

A classic runner’s injury, for instance, is a repetitive strain injury called iliotibial band syndrome. One possible cause of this condition is muscle imbalance: a relative weakness of the gluteus medius and minimus. (This is a controversial theory, and I don’t quite buy it.11) These muscles are lateral stabilizers; they control side-to-side movement of the hips. On a flat surface, they aren’t needed much — it’s easy to stay upright on a flat surface. They don’t exactly atrophy, but the other leg muscles get disproportionately stronger. When you see people running sideways, this is partly what they are trying to prevent. It’s a good idea, but it’s futile unless they do at least half the run that way.

The seawall around Stanley park in Vancouver, Canada, one of the most popular running routes on Earth — and deserted when I took this photo, because it had just been re-paved, and it wasn’t officially re-opened. Shh.

Shin splints on the road

Unyielding concrete and asphalt pose a number of potential stresses, but the most obvious is the triple threat of the three main kinds of shin splints: (1) medial tibial stress syndrome, (2) compartment syndrome, and (3) stress fractures. (The term “shin splints” is not diagnostically meaningful in itself: it just means “shin pain.”) All three can be show-stoppers for serious runners.

Intriguingly, the evidence shows very clearly that the overall degree of impact is not actually a significant risk factor, while the speed with which you hit the pavement — the loading rate — is only a modest factor.13 (This might seem rather counter-intuitive at first, but it’s not so strange when you consider that there are undoubtedly many, many other variables. For a more complete discussion of the evidence about impact, see the shin splints tutorial.) Nevertheless, it’s a factor we can do something about, and the surface you’re running on is a big determinant of loading rate: it’s obviously more jarring to run on harder surfaces.

Human anatomy and physiology is well designed for shock absorption, but there are limits, and highly repetitive pounding on a hard surface may break the tibia (stress fracture). The tibialis anterior and other shin muscles have the job of preventing the foot from “slapping” — if something didn’t hold the foot up a little bit after heel-strike, the forefoot would slap down loudly and awkwardly. On a hard surface, the transition from heel strike is particularly intense. It’s the tibialis anterior muscle that controls it, with strong and well-timed eccentric contractions that ease the foot down, somewhat like the biceps lowering a barbell — except it’s more like catching a barbell that’s being dropped from five feet up … hundreds of times in a row. You see the problem.

Eccentric contractions are a bit strange. How, exactly, does a muscle both contract and lengthen at the same time? There is obviously a need to lengthen muscle while still bearing a load, or you could never put anything down. But, believe it or not, despite a working theory about the chemistry of muscle contraction that’s been around for decades, no one really knows how eccentric contractions actually work.14 About all we do know is that they tend to cause much greater delayed onset (post-exercise) muscle soreness. Presumably, this also means that they are harder on the muscle.

When the tibialis anterior has been sufficiently irritated, it tends to develop severe myofascial trigger points and swell — and by an accident of anatomy, its muscle sheath is a bit small, creating a dangerous situation. Without room to swell, it only gets more irritated, and tries to swell more … you get the picture. This is a physiological design flaw.

The same forces that can put the tibialis anterior in this sorry state may also start to simply strain the connective tissues wrapping around the bone and/or the underlying bone (medial tibial stress syndrome). Ouch.

Patellofemoral pain on the road

Diagram of relative location of IT band pain and patellofemoral pain, also known as anterior knee pain.

Both kinds of runners knee, IT band syndrome and patellofemoral pain, are probably aggravated by running on hard and even surfaces.

Yet another common runner’s injury may be bothered by hard surfaces: patellofemoral syndrome. Unlike with shin splints, there’s no superficially obvious problem with impact forces. The actual problem isn’t hard to understand, though: the less give there is in the road, the more the legs have to do the job of shock absorption. The body does this well, but it means that you are using the joints more — a tiny little bit more flex with every step. It adds up!

When you step off the road, or even a slightly softer road, there’s just a little bit less for the joints to do.

The problem with patellofemoral pain is usually tissue fatigue around or near the joint between the patella and the femur. This joint is always working hard. Pressures under the kneecap are spectacular even when nothing spectacular is going on: when the knee is flexed, it’s naturally cinched up against the front of the knee so hard that you literally couldn’t get it off with a crowbar (the bone before you could move it. It’s amazing that the tissue mostly handles these pressures. But of course if we chronically demand maximum performance, they may stop coping so well.

Plantar fasciitis on the road

Sandpaper your arches until they are raw and then go for a barefoot run: that’s what plantar fasciitis feels like. This common repetitive strain injury involves fatigue of the connective tissues of the arch, the plantar fascia, which are part of the system that makes the arch springy. The less give there is in the running surface, the more the arch has to do its thing. The less variation there is in the running surface, the more exactly the same the loading on the plantar fascia with every step.

There’s no direct evidence this is actually a problem — it’s mostly just a reasonable theory. However, there is some decent indirect evidence. For instance, we know that plantar fasciitis is prevalent in manufacturing, where workers usually work on concrete, and “work stations that decrease the percentage of time walking or standing on hard surfaces may lower the risk for plantar fasciitis.”15 Chances are good that’s true for runners too, because they use hard surfaces even more intensely.

Another data point: people with plantar fasciitis really don’t like to stand on pavement, and find shoes with good arch support to be a great relief. These are classic features of the condition.

Alternatives to running on hard, even surfaces

Softer and uneven surfaces have their own risks of course — like tripping! and twisting ankles — but if you’re prone to recurrence of any of the injuries discussed above, you may prefer some new risks for a while.

Even chip trails and other groomed trails may not be enough of a departure from paved surfaces — it may be soft, but it’s still same-surface running. We have evolved miraculously complex reflexes and musculature that can keep us upright on virtually any surface, even shifting surfaces like the deck of a ship. To develop and maintain a well-rounded fitness, all of those reflexes and musculature need to be constantly stimulated and challenged.

Ideally, your run should be on soft, constantly changing, and unstable surfaces — but not so unstable that your risk of tripping and spraining spikes absurdly high, of course.

I live in downtown Vancouver, which is runner’s Heaven: miles of scenic seawall running. The seawall itself is paved. But for most of its length, you can stay off of it, and run on beaches or grass, hop over logs and benches, go up and down hills, even scramble over rocks.

Alas, most people don’t have the option of running on the beach. The solution is what I call “urban cross-country.” The key to urban cross-country is creativity: do anything you can to vary your running surface, and to get off the concrete every chance you get. Put parks on your route whenever possible. If it’s a small one, run around it on the grass five times before continuing. No park? Run on people’s lawns! The sidewalk is not your path: everything else is. Look for stairs and steep hills, and put them in your route. Run with one foot on the curb and one foot off for a block.

Getting the idea? Just do anything you can think of to keep changing the stresses on your body.

But the devil is in the details. For instance, all-terrain running is probably a different kind of risk factor for iliotibial band syndrome specifically, because that condition is infamously irritated by running down hills.

Roger Davies and natural posture running

Roger Davies, running researcher and medal winner in the 800-metre run at the 2005 World Masters Games in Spain, recommends a running technique in a similar spirit called “natural posture” running. He believes that adult runners need to imitate the running style of children, leaning forward with their arms swinging and feet flat. “Your body has to get back to its natural self,” Davies says. “Loose shoulders, loose hips. A lot of us are very tight.”16

The loss of well-rounded fitness in our society is in part the inspiration for the “core stability” exercising trend, and explains the burgeoning popularity of Pilates and Yoga. We probably lose core stability without a variety of exercise. While core stability exercise may have its place in our lives, core stability training for its own sake would probably be much less necessary if only we would walk and run on the sand or the grass more often.


About Paul Ingraham

Headshot of Paul Ingraham, short hair, neat beard, suit jacket.

I am a science writer, former massage therapist, and I was the assistant editor at ScienceBasedMedicine.org for several years. I have had my share of injuries and pain challenges as a runner and ultimate player. My wife and I live in downtown Vancouver, Canada. See my full bio and qualifications, or my blog, Writerly. You might run into me on Facebook or Twitter.

Related Reading

What’s new in this article?

Five updates have been logged for this article. All PainScience.com updates are logged to show a long term commitment to quality, accuracy, and currency. more Like good footnotes, update logging sets PainScience.com apart from most other health websites and blogs. It’s fine print, but important fine print, in the same spirit of transparency as the editing history available for Wikipedia pages.

I log any change to articles that might be of interest to a keen reader. Complete update logging started in 2016. Prior to that, I only logged major updates for the most popular and controversial articles.

See the What’s New? page for updates to all recent site updates.

More introduction polish and much more thorough rebuttals the the arguments against the riskiness of running on pavement.

Another wave of revisions: the scientific uncertainties now permeate the whole intro; all the arguments against “running pavement is risky” are now much more thorough; title is now a question: “Is Running on Pavement Risky?”

New section, “Citation badly needed! Are roads really risky?” This now introduces the uncertainties on this topic more thoroughly, with some relevant links and citations. More citations and more thorough analysis of them coming soon.

The premise of this article needs questioning. I’ve added a prominent, important caution to the introduction about the lack of evidence that any running surface is actually risky. I also removed and changed some a few particularly overconfident statements about injury risk. Major revisions forthcoming.

Added a new section about plantar fasciitis.

Notes

  1. Lieberman DE, Bramble DM. The evolution of marathon running: capabilities in humans. Sports Med. 2007;37(4-5):288–90. PubMed #17465590. “Human endurance running performance capabilities compare favourably with those of other mammals and probably emerged sometime around 2 million years ago in order to help meat-eating hominids compete with other carnivores.” BACK TO TEXT
  2. The original quote is from Benjamin Franklin: “The definition of insanity is doing the same thing over and over and expecting different results.” BACK TO TEXT
  3. NYTimes.com [Internet]. Kolata G. For Runners, Soft Surface Can Be Just as Hard on the Body; 2016 December 29 [cited 17 Jan 19]. “Exercise researchers say there are no rigorous gold-standard studies in which large numbers of people were assigned to run on soft or hard surfaces, then followed to compare injury rates. … It’s too hard to recruit large numbers of people willing to be randomly assigned to one surface or another for their runs.” BACK TO TEXT
  4. Williams PT. Effects of running and walking on osteoarthritis and hip replacement risk. Med Sci Sports Exerc. 2013 Jul;45(7):1292–7. PubMed #23377837.

    This analysis of about a zillion runners versus walkers found that “running significantly reduced arthritis and hip replacement risk”…but due in large part to the fact that runners were typically skinnier. So weight was a trump factor here.

    This data flies in the face of the common assumption that running is much harder on the joints. Instead, what it clearly shows is that running is either neutral or helpful, and weight is a much more important factor regardless of whether you walk or run.

    BACK TO TEXT
  5. Ferris DP, Liang K, Farley CT. Runners adjust leg stiffness for their first step on a new running surface. J Biomech. 1999 Aug;32(8):787–94. PubMed #10433420. BACK TO TEXT
  6. van der Worp H, Vrielink JW, Bredeweg SW. Do runners who suffer injuries have higher vertical ground reaction forces than those who remain injury-free? A systematic review and meta-analysis. Br J Sports Med. 2016 Apr;50(8):450–7. PubMed #26729857. BACK TO TEXT
  7. Altman AR, Davis IS. Prospective comparison of running injuries between shod and barefoot runners. Br J Sports Med. 2016 Apr;50(8):476–80. PubMed #26130697. For this test, 200 experienced runners were studied over the course of a year. The results are clear and unsurprising: there was no important difference in injury rates, just the types of injuries. Each was better in some ways, worse in others. Although the paper emphasizes “fewer overall injuries” for barefoot runners, injury rates are what matters — the number of injuries per 1,000 kilometres, say — and they were “not statistically different between groups due to significantly less mileage run in the barefoot group.” BACK TO TEXT
  8. Bohne M, Abendroth-Smith J. Effects of hiking downhill using trekking poles while carrying external loads. Med Sci Sports Exerc. 2007 Jan;39(1):177–183. PubMed #17218900. PainSci #56827.

    For this study, fifteen experienced male hikers walked down a 36˚ test ramp 30 times with poles and 30 times without, and with three different loads: nothing, a light pack, and a heavy pack (30% of bodyweight). A force plate in the ramp measured the intensity of their foot impact, and they were videotaped to get measurements of their joint movement. Consistent with other cited research, the use of poles resulted in significantly reduced forces, movement, and power around the knees and ankles. Interestingly, it didn’t matter how heavy the pack was: “packs only resulted in a larger power generation at the hip.”

    BACK TO TEXT
  9. Even though Altman et al showed that injury rates were the same in barefoot runners, there’s an incredibly important caveat: the barefoot runners they tested put in just 24km/week, while runners in shoes ran 41km/week without an increase in injury rate! As Alex Hutchinson put it for Runner’s World, “The only way the comparison has any relevance is if they’re arguing that barefoot running reduces injuries by preventing you from running as much as you’d like.” It’s all still debatable, but in my opinion I think both common sense and some evidence now suggest that pounding the pavement without padding is almost certainly more injurious — which suggests that pounding pavement is probably more stressful than pounding trail. BACK TO TEXT
  10. Zadpoor AA, Nikooyan AA. The relationship between lower-extremity stress fractures and the ground reaction force: a systematic review. Clin Biomech (Bristol, Avon). 2011 Jan;26(1):23–8. PubMed #20846765.

    This study of studies tries to determine if stress fractures are connected to ground reaction forces (the force of your strike) or with loading rates (how fast the force is applied, i.e. more slowly or more jarring). They found that the force you are striking with has no connection with stress fractures, but the “the vertical loading rate was found to be significantly different between the two groups.” So it’s not how hard you hit the ground, but how fast you hit it. However, the science was murky on something important: the correlation identified is statistically “significant,” but the size of the correlation is not impressive. So it’s how fast you hit the ground, but probably only to a modest degree. Presumably there are quite a few variables involved, which reduces the importance of even the most seemingly obvious risk factors.

    BACK TO TEXT
  11. But you’ll also hear it from countless physical therapists these days, so let’s run with it for the sake of this point. For a full discussion about this, see Does Hip Strengthening Work for Runner’s Knee?. BACK TO TEXT
  12. Compartment syndrome is a vicious cycle of increasing pressure in the sausage-wrapping-like sheath of connective tissue that contains the shin musculature. It is not self-limiting, and has the potential to literally kill the muscles of your shin … or even you via blood poisoning. See the shin splints tutorial for more safety information about compartment syndrome. BACK TO TEXT
  13. Zadpoor AA, Nikooyan AA. The relationship between lower-extremity stress fractures and the ground reaction force: a systematic review. Clin Biomech (Bristol, Avon). 2011 Jan;26(1):23–8. PubMed #20846765.

    This study of studies tries to determine if stress fractures are connected to ground reaction forces (the force of your strike) or with loading rates (how fast the force is applied, i.e. more slowly or more jarring). They found that the force you are striking with has no connection with stress fractures, but the “the vertical loading rate was found to be significantly different between the two groups.” So it’s not how hard you hit the ground, but how fast you hit it. However, the science was murky on something important: the correlation identified is statistically “significant,” but the size of the correlation is not impressive. So it’s how fast you hit the ground, but probably only to a modest degree. Presumably there are quite a few variables involved, which reduces the importance of even the most seemingly obvious risk factors.

    BACK TO TEXT
  14. For more detail, see another article on PainScience.com, Eccentric Contraction: A weird bit of muscle physiology. BACK TO TEXT
  15. Werner RA, Gell N, Hartigan A, Wiggerman N, Keyserling WM. Risk factors for plantar fasciitis among assembly plant workers. PM R. 2010 Feb;2(2):110–6; quiz 1 p following 167. PubMed #20193937. BACK TO TEXT
  16. Roger Davies was quoted in a Canadian Broadcasting Corporation article published Mar 3, 06. BACK TO TEXT