WALKING ON AIR
DO YOU REALLY WANT TO GO FOR A RUN?
Is running on hard surfaces really bad for the joints? Fitness Guru Matt Linsdell explains why you’re probably better off not bothering with those über-expensive, low impact running shoes. It’s time to stop fearing the pavement.
In the Northern Hemisphere days are getting longer. The air is feeling warmer and the snow has melted – so I can actually see the black surface of my driveway. This must mean it is time to do some outdoor running. When the snow melts a bit more (I live near Ottawa), I’ll be able to run on the vast network of trails right outside my house. As a personal trainer I often hear runners espousing the virtues of softer surfaces underfoot. Trail running is known for being good for you because the ground is softer than the hard pavement. I’m told it will be less likely to get an injury on those nice soft surfaces. Conversely, I also hear of the evils of the asphalt, with its hard, unrelenting character, damaging the joints.
Runner after runner adamantly swears how
gentle trail running is on the body compared to man’s ‘evil’ pavement creation. Good sense or nonsense? It sure sounds like the naturalistic
fallacy to me (if you consider groomed hiking trails to be natural, that is). Let us explore these ideas together. And by ‘together’, I really mean that you just read what I write and assume I’m 100% correct…(!)
A running myth?
Concrete doesn’t offer much give compared to the earth that trees and shrubs grow in. So, it is logical to believe that the impact of a runner’s foot repeatedly hitting a hard surface will result in higher stresses to be absorbed by the body compared to the same runner’s foot striking softer materials. To some degree this is true, but evolution considered this long before Nike did. When we (of the genus Homo) rose up from quadrapedal movement to bipedal walking, our feet underwent selection pressures that made them better at dealing with stresses from all kinds of surfaces – hard and soft. Firstly, take look at your heel. It is big and wide. This shape is good at absorbing and distributing the forces that assault your body when the heel strikes the ground. Also, if you look at the bones of the human foot from a side view (see X-ray photo) you can see that when the heel and front foot touch the ground, the middle of the foot stays suspended. For the mechanical types amongst you, this feature might remind you of a leaf spring. The curved shape dissipates some of the forces acting on the body during running – in the same way a car suspension does. There is also extra shock absorption from muscles and tendons in the ankle and leg. Add to all of this the protective nature of a running shoe
(to guard you from sharp rocks, hypodermic needles, searing hot surfaces or numbingly cold ground) and you’ve got a match made on Earth. Thanks to our big brains for developing trainers, we have a readily available technology in an array of sizes and colours that allows over-fed organisms to aimlessly perambulate in an attempt to keep their hearts pumping. Life is good. So shoes and the structure of our foot make concerns about the density of a running surface mostly moot. I’m sure someone could design a study to find a measurable difference in the total force subjected to the body over a large distance, but that wouldn’t apply to normal people out for some aerobic exercise. We can examine that evidence when it arises. For the running surface to make a real difference, you will need to be running huge distances day-after-day.
Running in the woods
So is there a benefit to running on trails? Well, yes. But it isn’t because of the soft-ish forest floor. It is literally because of changing directions. Woodland trails tend to meander left and right and the pitch goes up and down. Sometimes there are puddles or logs to jump over. These combined movements result in spreading out of the wear on the ankle, knee, and hip joints. At least it does in theory – although I’ve yet to find any research to confirm it. I don’t know that any exists, so for now let’s just consider it in a critical way by comparing trail running to treadmill running. On the treadmill you can change the speed of the belt and the pitch of the entire machine. And that’s about it, until you switch the thing off or fall over and get whipped off the back. We are able to compare treadmill running stresses to occupational repetitive strain injuries. For example, consider a laboratory technician who micro-pipettes hundreds and hundreds of samples every day. Each little click is no big deal to the hand and wrist, but over time it can cripple the extremities. Repetitive Strain Injuries (RSI) and Cumulative Trauma Disorders (CTD) are overuse injuries that can cause endless suffering to people who work in labs, at computers, or who swing a hammer day in and day out. In contrast, trail running, while still repetitive, introduces more variety. Sideways movements seem to spread out the muscle and joint wear by requiring the runner to rotate at the hips slightly and change the angle of the foot. The runner struggles through muddy sections, up and down undulating trails. Each little change helps to add to the variety that can help prevent an overuse injury. But it won’t prevent it altogether: excessive training, even on trails, will result in an injury just like any other excessive amount will.
My hope, Guru Readers, is that my opinions make sense and that you will agree. Now I’m off to the trails to use what natural selection has so kindly supplied me, plus an expensive shoe to cover it. And I won’t worry that I have to run on the street to get to where the squishy trail begins. My only concerns are for bears. There are hungry bears in them there hills and I really hope they don’t get me.