Surface tension

One of the reasons the anti-road brigade say that trail running is ‘better’, is that it puts less stress on the body. Intuitively, it makes sense (softer surface equals a softer landing, right?) but there has been surprisingly little research to back up the claim…

Are you a road runner or a trail runner? It’s not a question that I could answer definitively – I run where the day’s route takes me, be it through a leaf-carpeted woodland (this morning), along a city street (last week) or across a muddy field (yesterday). Each has its own pleasures and challenges.

But some runners can be very snobby about surface. A trail aficionado recently commented on Twitter that ‘people who do road marathons hate themselves.’  You’ll find similar disparaging remarks about tarmac enthusiasts if you look at trail running forums and specialist publications. The gist of it is that road running is deathly dull/bad for you/a poor substitute and that running off-road is in all ways more fun, healthier and generally superior. I think it’s an unfounded and unwelcome division – like vegans dissing vegetarians – we’re all runners, aren’t we?

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The tweet came to mind at the weekend, when I was toiling along a public footpath bordering a field that the farmer had decided to plough to the very edge of the barbed-wire fence. Each time my foot landed, the clump of earth underneath it would either crumble or roll, creating angles at my ankle and knee joints that would have a biomechanist brandishing their goniometer with alarm. Any views to be appreciated went unnoticed, since I had to keep my eyes firmly on the treacherous trail.

There was little relief to be had when I reached the stile, which was so overgrown with nettles that getting over it could have passed as a ‘I’m a celebrity…get me out of here’-style challenge. ‘Fun, this is not,’ I thought to myself. Fifteen minutes later, the nettle stings fading (the secret is to avoid touching them) I was floating along a blissfully smooth tarmac lane. The ironed-flat surface rendered me surefooted enough to appreciate my surroundings – ripe blackberries in the hedgerow, leaves just turning in the autumn sunshine. My good mood was restored.

Now, I’m not claiming that road running is more enjoyable than trail; nor ‘better’ in any way. I love the ever-changing demands of an off-road run – one minute, mud is sucking at your trainers, the next you’re bounding through knee-high grass, leaping over tangled tree roots or skipping from rock to rock. But it’s hard to find any kind of rhythm – which is why I also relish the clean, rhythmic clip of feet on tarmac and the space that that metronomic movement seems to create in my head.

One of the reasons the anti-road brigade say that trail running is ‘better’, is that it puts less stress on the body. Intuitively, it makes sense (softer surface equals a softer landing, right?) but there has been surprisingly little research to back up the claim. In fact, studies seems to suggest that there’s a complex and entirely subconscious interplay between our limbs and the surfaces we run on: the ‘stiffer’ the surface, the ‘softer’ we make the limbs, and vice versa. It’s known as ‘muscle tuning’. This continual adjustment of limb stiffness to match the surface the brain expects us to land on means that the resultant force is pretty much unchanged regardless of surface.

More recently, researchers have posited the theory that trail running may be healthier (though there is not data to prove that trail runners sustain fewer injuries as yet) because of the variety offered by the mixed terrain and undulations. Each footstep is slightly different from the last one and the next one, so the forces exerted on the body are applied in slightly different ways, reducing the risk of overuse. This makes perfect sense and is probably also why varying your running shoes, rather than wearing the same pair all the time, has been linked to a lower incidence of injury.

Variety is almost always better than doing the same thing all the time – but when it comes to running surfaces there’s no reason why a brightly-lit town pavement or a country B-road should not form part of that variety.

This article previously appeared in my Murphy’s Lore column in Runner’s World magazine

 

 

Author: Sam Murphy

Journalist, author, running coach and educator

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