Five years ago trail running barely existed, these days though you can barely walk through an outdoor shop without tripping over piles of trail-running shoes, so what's going on and what exactly is trail running?
In simple terms, it's pretty much running on the paths and bridleways you'd normally walk along. Open mountain sides remain the preserve of goat-like fell-running whippets, but trail-running is a lot more accessible and less fierce. Best of all, at base all you need is a pair of suitable running shoes and lightweight clothing.
And don't stop reading just because you're not a runner, the great thing about trail-running shoes is that they also make fantastic lightweight walking footwear. So even if you're not a runner, don't discount using trail-running shoes for walking.
The crossover doesn't end there - running off road is some of the best training you can do for hill walking, climbing and mountaineering. Not only do you get all the cardio-vascular benefits and leg muscle work-out you'd expect from road running, but uneven off-road terrain has real benefits and amplifies the effect.
Because your feet are constantly landing at different angles, your proprioceptor response, coordination, balance and agility will all improve and the supporting muscles, ligaments and tendons around your knee, ankle and hip joints will be strengthened as you stabilise yourself on each foot strike. Even your brain gets a work-out as you have to think about each foot placement on the trail.
Finally, softer off-road surfaces are kinder to your joints than the constant jarring of running on roads and pavements, so you're less likely to develop knee or shin problems.
Your shoes are the most important bit of kit and well worth choosing carefully. And there's a lot of choice out there, new brands like Carn include suitable shoes in their line-ups and established brands like Timberland are expanding into the area with a new Mountain Athletics range aimed specifically at trail runners and lightweight walkers.
Starting from the bottom, the outsole should be made from rubber that's grippy enough to cope with rock, but has enough tread to deal with softer ground, look for prominent lugs and check rubber hardness with your thumb nail.
Next, cushioning is down to the mid-sole, usually made from EVA foam rubber. This should be thinner and lower than pure road shoes for better balance, but still thick enough to offer cushioning on harder surfaces. State of the art shoes will use different hardnesses of rubber to optimise your foot strike and keep things stable. Look for different coloured foam.
The next crucial element, you can't see, but you can feel. Inside the shoe will be some sort of stiffening plate moulded into the chassis. Ideally the shoe should bend easily fore and after, but resist twisting in the middle of the shoe. If you grasp heel and toe and twist in different directions, the middle of the shoe shouldn't twist much if at all.
Finally there are the uppers. The heel should have a stiff cup around it which is crucial for stability. We'd also look for rubber reinforcement at the toe end to protect the uppers from rocks and rubble and a lacing system that holds your foot firmly in place and doesn't allow it to slide around inside the shoe. Generally we'd suggest a snug fit for that reason, but make sure your toes don't slide into the front of the shoe when running downhill.
Last but not least, winter-friendly shoes tend to have a waterproof liner while those aimed at hotter conditions use more breathable mesh uppers.
Ideally you should buy from a good specialist retailer with a choice of brands and models.
Shoes For Walking
The same basic principles are true if you're buying trail-runners for lightweight walking use, but be aware that running shoes used for walking won't last as long as traditional boots, even though they're fantastically comfortable.
If you're wary of lightweight shoes, some trail-runners also come in a 'mid' version which gives a little more ankle protection and can make a good compromise.
There's plenty of running kit out there, but shorts, leggings, a baselayer top and a lightweight windproof plus maybe a waterproof for really bad downpours and some gloves and a hat should see you right on most days. On longer days a bum-bag with water and some energy bars makes a lot of sense too. Choose your socks carefully to give good wicking and cushioning in strategic areas like heels, toes and the balls of your feet.
We could write a whole book about running - and people have - but start gently if you're not used to regular running, take shorter strides and build up slowly to avoid injury. No more than 10 per-cent extra per week is a typical suggestion.
Even if you already run on the road, remember that your pace will be slower on the trail and start with less ambitious surfaces before throwing yourself at high mountain paths. Don't fret, you'll get there soon enough.
One Last Thing
The great thing about trail-running is that magical feeling of freedom you get from moving fast and easily through the outdoors. It's a proper grin-inducing way of seeing the hills and there's something beautifully escapist about pulling on your runnings shoes and simply taking off. Enjoy.
Jon Doran, Outdoorsmagic Editor