If you run on trails, one of the most important skills you need to have is knowing how not to sprain an ankle or break one of those 26 beautiful bones you have in each foot. Trails, by nature, are Indiana-Jones obstacle courses of holes, rocks, and roots.

For me, to run safely and confidently on rough ground means having my feet be not only strong, but very flexible and resilient. Then, if I accidentally step in a hole or wedge a foot between a couple of rocks and start to twist my ankle, the important thing is to let myself relax into the unexpected motion a little, NOT to try to brace myself against it.

Years ago, I learned about this from downhill skiers. I’d traveled to some of the great ski trails—at Killington, Alta, Sun Valley, and Kitzbuhel, and everywhere I noticed that beginners tended to try to brace themselves by stiffening their knees when they hit bumps or ruts, to try to keep from falling. The result: They fell, often badly. The instructors had to teach them to let the knees bend and “give” in those situations. If you watched the expert skiers, their knees and hips were continuously going with the bumps, not fighting them.

The reason for this approach, whether you’re skiing or running, is that you are generating far too much leverage or torque to suddenly brace against without something getting broken or sprained. But if you yield a little to the initial twist, it exerts less brute force and also buys you a fraction of a second to re-balance yourself a little—and quickly shift your weight to the other foot

You may recall the famous running doctor of the 1970s and ‘80s, George Sheehan, author of Running and Being and several other best-selling books. I ran with George in the very first New York Marathon, in 1970, when the road-running boom was just beginning. Sheehan’s wisdom about the running life was awesome (it still is), but there was one thing I think he got wrong. Sheehan didn’t recommend running on trails, because he was afraid it would be too hazardous to the feet and ankles. I think just the opposite: that running over rough ground exercises many more muscle groups than running on flat roads, and makes you better able to recover when you stumble. Trails are good for foot strength.

While Sheehan may have come along a generation too soon to appreciate the evidence we now have that running on rough ground is not only good for the feet but is how we evolved as humans, he might have been more enthusiastic about the trails if he’d paid closer attention to his own most famous advice: “Listen to your body!” I think Sheehan was thinking mainly about the importance of “listening” to your heart, lungs, and gut, and to the overall sensations of fatigue, dehydration, or overtraining—but only to the legs when they were in pain. Yet, the legs and feet send a continuous stream of messages other than pain. If he had paid closer attention (and this goes for me, too), he would have heard them saying “We LIKE rough ground! It gives play (and brings back to life) to all the muscles and tendons that played a role in our survival for 2 million years. And after being imprisoned in rigid shoes or boots for the past few thousand years, being able to get out on the trail again feels really good!

Article by Ed Ayres

You can read more about Ed and his extraordinary running life at his blog: endurance and sustainability and please feel free to interact with him!