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I've been running somewhat regularly for about 5 years now. I have always run on the road. For the last 4 weeks I have a new route that requires I run on a sidewalk. During this time I have developed slight pain in my repaired ankle. I'm about 230lb's (have been between 255 and 230 this whole time) and my ankle has 2 plates and 12 screws in it.

I've had knee pain and other leg pain in the past which regular stretching relieved. So far the ankle has not stopped aching (on and off). Could the hardness of the sidewalk make a big enough difference to my body to begin a serious problem?

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  • 1
    Wanted to update on my personal experience now a month later. My pain has mostly gone away - I have focused on gentle stretching of my legs in a variety of ways. I've continued running on the sidewalks and I'm running approximately 9 miles a week on sidewalks and another 3-6 on roads.
    – Adam Heeg
    Sep 17, 2015 at 20:10
  • My primary reason for running on the roads rather than on the sidewalks, has always been that the roads usually are way smoother than the sidewalks. On the sidewalks (in DK) I often see small holes and tiles that are not quite level making it easier to trip and hurt yourself.
    – Tonny Madsen
    Sep 21, 2015 at 9:02

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The surface you are running on may play a role in how your body reacts. There’s an often quoted study co-authored by Southern California podiatrist John Pagliano that states…

"… one of the five leading causes of injury is "improper" running surfaces........concrete is approximately 10 times harder than asphalt, so all your bones, muscles and connective tissues get pummeled. In other words, welcome to stress fracture city"

And, an additional post attributed to Bill Nye (“the science guy”) states….

"Now get this ... there are infinite different types of concrete. It has to do with the mixture with determines the strength (measured in pounds per square inch or psi). There are many types of concrete because of the different applications, in buildings, as sidewalks, used in planters or parking lot bumpers, etc. Asphalt is different in that is only used for roads, so it's basically residential road, commercial road (high use) or highway. The asphalt on maple drive can be softer than on main street, and main street can be softer than the interstate. Asphalt (400-600 psi) is "softer" than concrete (typically 3000 psi) meaning that it takes compression and then expands back to its original state. Concrete sidewalks and paths are the "softest" concrete to run on, about 3000 or 4000 psi. Worst concrete substance to run on: Airstrip, typically 8000 - 10000 psi."

So, your body may be reacting to a different PSI since you’ve changed your training route.

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  • this is what I feared, and I supposed my ankle is more susceptible to this than the rest of my body. Thank you for the links too.
    – Adam Heeg
    Aug 20, 2015 at 15:22
  • The difference between road and sidewalk hardness is negligible. If you are concerned about this, run on a rubber track or in the grass. Many (myself included) prefer the road because it is smoother. Navigating all the cracks, tree roots, etc can be tricky as you tire.
    – William Sturgiss
    Aug 21, 2015 at 14:28
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While concrete may be a harder surface than asphalt, other than preconceived perceptions, there is not an appreciable difference in deflection (Force returned from a surface) between concrete and asphalt.

There is a difference between grass, dirt, rubberized track surfaces, etc., but between asphalt and concrete any difference that you perceive is perception only, and not real. You simply don't generate the PSI force necessary to make a difference.

http://hypertextbook.com/facts/1999/SaraBirnbaum.shtml

http://www.translatorscafe.com/cafe/units-converter/pressure/calculator/newton-per-square-meter-%5BN/m%5E2%5D-to-psi-%5Bpsi%5D/

http://www.chirunning.com/blog/entry/comparison-of-harvard-study-results-with-chirunning

There have also been studies where the forces of various surfaces were compared with running strides as shown by the following links

Study comparing rubber, grass, concrete and asphalt

Forty-seven adult recreational runners ran twice for 40 m on all four different surfaces at 12 ± 5% km · h(-1). Peak pressure, pressure-time integral, and contact time were recorded by Pedar X insoles. Asphalt and concrete were similar for all plantar variables and pressure zones

Study comparing ground reaction forces

No significant differences were detected among the surfaces for shoe reaction forces, contact time, or impulse (P > 0.05). This implies that runners who choose to run on stiffer surfaces are not exposing themselves to additional risk as a result of loading but possibly because of internal compensatory mechanisms. However, these results may not apply to all runners.

This last one does indicate that there may be a difference in how people run on various surfaces, but the surfaces themselves are largely irrelevant.

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  • After reviewing your links I see no reference to concrete vs paved road. I could have missed something, if so I apologize. However, these don't apparently address my question or support your claim of there not being an appreciable difference between concrete and asphalt.
    – Adam Heeg
    Aug 21, 2015 at 18:19
  • The first link shows all the newton forces from various types of running. The second link is a calculator that converts Newtons to PSI. Typical PSI of asphalt is 500-800, concrete 3000+ (Depending on type). The final paper shows ground reaction forces for various strikes, most coming in the 40-60 PSI range. The human foot just doesn't generate enough PSI for there to be a difference between asphalt and concrete. It's apocryphal lore, nothing more.
    – JohnP ♦
    Aug 21, 2015 at 19:52
  • @AdamHeeg - See the added details, I moved them from comments to the answer.
    – JohnP ♦
    Aug 21, 2015 at 20:04
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Your problem might not be with the hardness of the ground you're running on. If you run on a sidewalk that is on the same level on the road you shouldn't see much difference. I think the issue here is the fact that sidewalks are not as straight as paved road. Most sidewalks have bigger slopes going down, up, then back down again. And the sidewalks stop when you reach entrances to parking lots. Because you ran for so long on paved road, your feet had no problem running because you don't have to worry about any of that. Where as when you run on sidewalks, your legs have to constantly adjust to the constant slopes, cracks, and when you switch from sidewalk to road to sidewalk when you pass parking lot entrances.

In short, sidewalks are not are straight and leveled as roads. That's what's probably taking a toll on your ankle.

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  • I do have more vertical changes, but not any side to side changes. For my repaired ankle that can make a difference since it has severely restricted movement forward and backward. This could be a part of it.
    – Adam Heeg
    Aug 20, 2015 at 15:21
  • Another thing which may be affecting you is sideways tilt. One of the sidewalks by my house is tilted slightly sideways due to shifting of the hillside beside it. When I run along there, I get a disproportionate amount of stress on the ankle closer to the road because it's having to move that fraction of an inch further each time. Ultimately, the variation is probably better for you. It's exercising muscles in ways that a more regimented street does not.
    – Sean Duggan ♦
    Aug 21, 2015 at 11:51
  • @SeanDuggan yes, same here. This is why track runners almost always run on tracks or you see them a lot on roads. In some high school sand colleges, track runners avoid sidewalks because of ankle injury risks. I have some friends that used to be in track and always ran on the side of roads or paved bike trails.
    – MB41
    Aug 21, 2015 at 14:11

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