by The Mizuno Shoe Guy
There’s no getting around it: Road running is hard on the body. It just is. Especially since the two predominant surfaces most of us run on are concrete and/or asphalt (macadam). Or a combination of the two. Both are unforgiving surfaces and, given a choice, many runners wonder which one is best for running.
A better question might be which one is worst? The answer is easy: Concrete is just about the hardest possible surface to run on. (Cobblestone streets are actually worse, but few cities in America have more than very short stretches of it.)
Let it be said in no uncertain terms: Concrete roads and sidewalks should be—if possible–avoided at all costs. Why? Concrete is simply much, much harder than even the firmest asphalt.
Asphalt might seem awfully hard and unforgiving too, but if you want to see the difference between it and concrete, pick up a hammer and smash it onto a concrete road, driveway, neighborhood sidewalk or curb. If you do, you’ll notice how the energy—the shock wave–reverberates from the hammer right up your hand, elbow and arm.
Then, try the hammer on asphalt. You will feel some reverberation on the asphalt too, but it won’t be nearly as pronounced as concrete. And check what the hammer did to the surface. It might have put a small dent into the asphalt, but there probably won’t be any mark on the concrete because it’s so darn hard.
In point of fact, it’s rock hard. Concrete is made up of cement which is basically crushed rock with some additives. Asphalt also has some cement and crushed rock, but it’s only a small percentage (usually about five percent). Studies have shown that concrete is anywhere from eight to 10 times harder than asphalt.
That’s a huge difference in how your body will feel after running on concrete (somewhat like your arm felt) as opposed to a run on an asphalt road.
When you run, your feet will contact the road with a force up to six times your body weight all concentrated in a small landing surface (your heel or the forefoot). You do that enough times on a concrete road and the accumulated impact forces can have a detrimental effect.
Sidewalks are even worse than concrete roads. The hardness factor is similar, but sidewalks are often cracked, slanted and full of pedestrians. In some cities, it’s impossible to avoid running on sidewalks—it’s safer than busy streets—but if it’s possible, you should probably limit your running on sidewalks to and from another running area.
The only “good” thing about running on concrete is it’s a faster surface. Since there’s almost no give, it returns energy better than asphalt. But this is hardly a positive in the long run.
Running a single workout on a concrete road or sidewalk usually won’t bother you too much, but continual running on concrete can lead to injuries as the leg muscles, joints and bones get pulverized by the hardness of the surface.
Again, if at all possible, avoid concrete roads and sidewalks. If you must run on such a surface, only do so occasionally.
In an ideal running world, the surface of choice for most runners would be dirt trails or some other soft surface such as bark or wood chips. Dirt trails aren’t as readily accessible as roads, but almost all major American cities have at least some dirt trails suitable for running. Even such major cities as New York City, Portland, Houston, Atlanta and San Francisco have areas with soft surface trails that are perfect for running. In rural areas, dirt roads are also great.
Two other common alternatives to road running are grass and treadmills. Grass is the gentlest surface and even though there are few entirely grass trails that extend far in any direction, some runs around soccer or football fields or in parks are easy on the body. So are treadmills with padded running surfaces.
Certainly, not every runner has a choice of varied running surfaces and must adapt their runs to their environment. If that’s you, it does make some sense to go out of your way for occasional runs on trails or in grassy parks to give your body a break from the roads.