Runners first taking the plunge into trail running often end up asking what the difference between road running shoes and trail running shoes is? The short answer is that they have been designed with the types of terrain often seen on technical trails in mind. The terrains might include water on the coarse, mud, rocks, tree roots and other dangers. They are designed with stopping loose dirt and debris from being able to enter the shoe in mind.
The next question of coarse is whether or not you need a trail shoe to tackle any of your weekly runs? Basically if any of your runs include single track trails or open trails that are steep, muddy or rocky then the answer is unequivocally yes! An appropriate pair of trail shoes will protect your feet from the terrain and obstacles you may encounter. They will also help you get better grip on the trails, making you faster and more efficient.
Now that you know that you need a pair of trail running shoes, what should you be looking for. Unfortunately the answer to this question is as varied as the terrains that these shoes can be used on. The most important factor when buying any shoes is comfort, this is also the case when buying trail runners. Keep in mind that these shoes will feel stiffer as they generally are intended to protect your feet not just cushion them.
If you're running on a rocky trail then you'll need trail shoes with a rock plate to protect your feet from pointy rocks and sticks on the track. This will help avoid ending up with bruised feet from stepping on a particularly pointy rock. Additionally having a wide base will help stabilise your feet when you are stepping on loose rocks. This wide base (outsole) will assist in avoiding rolling an ankle if you misjudge the stability of a rock.
Mud on the trail is sometimes unavoidable and if you want to avoid wet feet you will need trail running shoes that are water proof. The shoes will also need to feature large lugs to give you optimal grip on this slippery surface.
Running on sand is really tough work and one of the problems is getting sand in your shoes. There are a few things that runners can do to avoid this. You should definitely use gaiters and also use water proof shoes. This usually keeps all the sand out of your shoes. One word of caution though if you are prone to having sweaty feet this may not work so well for you. Additionally on soft sand you won't need as much cushioning as on rocky trails so trail racing shoes are a good option.
Steep downhill trails require plenty of cushioning to help alleviate some of the impact forces. They should be nice and stiff with a good snug fit and a toe box with ample room for your toes. You need to be secure though as you don't want to loose toe nails due to the shoes being too loose fitting. Finding the right fit as always is tricky and depends on what shape your feet are and this may actually change as you run more.