What to Wear for Trail Running and Mountain Races

One might think –particularly those who join the mountain-racing world from a non-mountain background like running– that trail-running clothes are pretty much the same as those worn for urban races.

And that’s actually partly true. The clothes worn for both activities have to be comfortable to run in, but there are obvious external factors on the mountain, particularly during long races, that make it necessary to take a different approach to race clothing. Runners have to be prepared to deal with abrupt weather changes –cold, extreme heat, rain, hail, snow, etc.– which can also occur in places far from shelter or protection. Unlike urban running, on the mountain it’s impossible to simply stop and grab a taxi, bus or sweeper car to take you home.

The event organizers behind practically every race require runners to carry mandatory gear in case of bad weather. Carrying a backpack is something that newcomers to mountain racing have to get used to. Here’s a guide to picking out the best backpack for your needs:

How to Choose your Trail Running Pack or Belt

Mountain-running clothes are designed to keep body temperature (36.5ºC or 97.7ºF) even. The body quickly loses heat in cold weather, making it crucial to cover up. However, with intense physical activity, extra thermal protection can easily make you sweat and overheat. This is very dangerous, because that sweat will cool you down as soon as you stop, slow down, or if the wind and cold suddenly get worse.

So there are three things you should always keep in mind:

  • Never put too many clothes on before starting the race. If you’re wearing so many layers that you’re warm before you even get moving, then you’ll definitely overheat when you start running. The old mountain rule applies here: “start cold” with as little clothing as possible, or plan to stop a few minutes into the race to strip off your jacket as soon as you’ve warmed up.
  • Everything you wear, besides meeting the weight, agility and protection requirements for the race, must be extremely breathable, quick drying, and capable of wicking away sweat.
  • It’s all about layering up: choose pieces you can layer in order to adapt to the different situations that you might encounter during the race.

We’ll skip shoes since we’ve already written a full article on how to choose the right running shoes:

How to Choose the Right Trail Running Shoes for You

Although we’ve divided our tips into winter/summer, we want to stress that the difference between winter and summer is relative on the mountain. In high mountain areas the temperature can drop drastically in summer and weather can include rain, hail, even snow. An ultra race like the Great Trail Trangoworld Aneto-Posets forces runners to deal with almost 3,000 meter (9842.5 feet) changes in elevation at night, passing through areas with snow, ice, and temperatures around 0ºC. And this is not an exception. Any small outing in the mountains can get complicated on the turn of a dime and can bring drastic changes in weather. The best advice is to always be prepared.


The vote on the use of tights in winter is practically unanimous. Tights are extremely comfortable, like a second skin, and support muscles, keeping them warm and protecting them from injuries as a result of shock, cold and vibrations. And –like compression socks– they protect runners from abrasions on the mountain. Tights come in different thicknesses for different outside temperatures.

Lurbel Ergo
However, not all tights are the same length. Runners are increasingly wearing ¾ tights as a compromise; these cover the leg until just below the knee and provide protection for this join. They can be worn with a pair of high socks that support the calf muscles and with tights that cover the entire leg, in layers in case you overheat. But many prefer to run in full-length tights.

Lurbel Ultra compresive
Running shorts are not a great option for cold climates, and are hardly ever used in winter on the mountain (that is, they are hardly ever worn alone, but can be worn over tights as extra protection or for a more aesthetic look).

The same thing happens with biker-style shorts, although their ease and comfort means you often see runners in these types of tights during training sessions or in less extreme weather.

Waterproof or protective pants are worn on top of tights in bad weather. Most runners wear or remove this outwear (like they would a jacket) depending on race or training circumstances.

Of course, it goes without saying that all tights and mountain clothes must be high-quality and high-performance: flat seams, lightweight, protective, stretchable, quick-drying and made from high-quality materials.

Summer/3 seasons

Things change in summer and what you wear when you run becomes more of a matter of taste.

Running shorts pop onto the scene, the garment of choice for many runners who prefer the enhanced comfort and coolness these shorts provide as opposed to the tighter-fitting biker-style shorts. But because they’re longer, reaching half-way down the thigh, short tights protect the muscles better and cover more of the leg if the weather starts to turn bad.

Luis Alberto Herrando. Photo: Barrabes/Adidas Terrex
Summer short tights are available in quite thin material that combines support and protection with comfort and breathability.

However, despite these pros and cons, the shorts vs. tights debate ultimately comes down to a question of comfort and preference.

Salomon Agile



While winter running clothes are different, the tips for dressing for mountain runs in the cold or winter is based on layering.

This system has two advantages:

  • It manages moisture extremely well: the first layer next to the skin quickly wicks away moisture towards to outer or next layer of clothing, preventing the body from cooling down as a result of evaporation.
  • It provides tremendous versatility. As conditions change, you can go from wearing just a T-shirt to a T-shirt with warmer clothing, or a waterproof and breathable outer layer with just a T-shirt underneath...
These are clothes designed for sports and are ultralight and, again, very technical. In winter, try to wear a tight-fitting bottom layer. It provides the most heat and works the best with the body. However, there are those who hate the compressed feeling and prefer wearing rather loose T-shirts.

Salomon Elevate Seamless
Some might think that long-sleeved shirts are the best kind to wear in winter. However, the general preference is to wear a long-sleeved shirt that can be converted into short sleeves. This two-in-one option increases versatility: you can wear the sleeves if you’re cold or keep the extra material down around your wrists to wear short sleeves if you get too hot.

Compressport ArmForce
The evolution in terms of windbreakers/waterproof garments has been tremendous. Shake-dry technology makes it possible –for the very first time– for runners to wear ultralight jackets that are waterproof enough (like a traditional windbreaker) to be effective in high-intensity activities.

The North Face Hyperair GoreTex Jacket
Summer/3 seasons

Here, once again, comfort and individual taste becomes more important. Warmer seasons are a time for outer garments, usually with a mesh back, that are ultralight and with ultra-quick drying, many with UV protection and minimal flat seams.

Dynafit Alpine Seamless Tank
There are a range of options to choose from: short sleeves, sleeveless, tighter, looser…it’s up to each runner to choose their favorite style and the one that provides the most comfort. Of course, as with all other running clothes, stay away from cotton, garments with seams, etc.

It’s also important to mention that tight T-shirts with sleeves (or sleeveless ones in the case of men’s shirts) have the tendency to cause chaffing, particularly on long runs. Some runners choose to use baby ointment on areas that are prone to chaffing, like the outside of the armpit.

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