The body is an all-terrain vehicle. We cannot run on concrete for long without consequences. But while most runners believe that the rigidity of concrete is the main problem, the continuity of the surface is just as bad and more than likely worse.

Unfortunately, most recreational runners are running on sidewalks. Any sunny morning, you can see hundreds of them... they never touch the grass or the sand. They have succumbed to the illusion that a hard, constant surface is the path of least resistance. But on an unvarying surface, your body is subjected to 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 no chance to adapt to other stresses. At best, same-surface and hard-surface runners become strong in one way, but weak in all the others — and therefore vulnerable to injury. The solution to most running problems is to get off the concrete.

A classic runner’s injury, for instance, is a kind of tendinitis called iliotibial band syndrome. It is caused by muscle imbalance, by a relative weakness of the gluteus maximus and minimus. 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.

Unyielding concrete and asphalt pose a number of difficulties for the runner’s anatomy, but none so great as the threat of shin splints: compartment syndrome, periostalgia, and stress fractures are the three conditions that typically cause shin pain. (Shin splints is not actually diagnostically meaningful: “shin splints” simply means “shin pain.”) All three can be show-stoppers. All three are caused or severely aggravated by running on a hard surface.
So don’t run on hard surfaces, kids — not if you can possibly avoid it!

The solution to most running problems is to get off the concrete. 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, everyone should run “cross-country.” Your run should be on soft, constantly changing and unstable surfaces. If you live near the beach, you’re in runner’s Heaven: just stay off the seawall. Run on the sand and the grass. Hop over logs and benches, go up and down hills, scramble over rocks. This is perfect!

• “The sidewalk is not your path: everything else is.”

Unfortunately, a lot of 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. You can’t go five blocks in this town without coming across at least a small community park. Put that park on your route, and when you get to it, run around it on the grass a few times before continuing. Everywhere you go, there is public grass, between the sidewalk and the road, or even on people’s lawns. Run on it! 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. Not only will this prevent injury, but it will make you much stronger.