Collection of common trail running terms and definitions

24 Feb, 2019 • by Admin

Definitive list explains the running terms and definitions you may come across when reading our blog, other websites and books, and speaking with other runners

Aid Station

A point during a race where you can replenish your water and food stashes, see supporters and seek medical assistance if required. The level of support at an aid station varies depending on the race and the individual aid station – some may be very basic, with just water on offer, others can include a sit-down buffet and sleeping arrangements for longer races.

Altitude Training (aka Elevation Training)

Training at a higher altitude than sea level, often done in mountain towns sitting at higher elevations, such as in the Alps and Colorado. Because you get used to training in thinner air (and develop more oxygen-carrying red blood cells), your performance is relatively better when returning to sea-level. People also emulate training at altitude by using elevation-training masks

Barefoot Running (aka Minimalist Running)

Can either mean running literally bare-footed, or, more commonly, wearing minimal, zero-drop running shoes to emulate the movement and feeling of running barefoot, but with a shoe to still protect your feet. Alastair has written more about barefoot running in this barefoot running guide.


Before I started running I thought ‘bonk’ meant something very different… in the running world, this describes the feeling you get where you run out of energy and feel a sudden wave of fatigue during a long run. Key to avoiding ‘bonking’ or ‘hitting the wall’ is making sure you get your running nutrition sorted, so that you don’t run out of energy. See our running nutrition articles for more advice in this area, and our nutrition reviews section for reviews of popular running gels, powders and other food.


Ok, so you may know what a running blister is, but how do you stop getting running blisters? Our popular posts: how to treat running blisters, stop getting blisters from running and blisters on the ball of my foot (from gait, not shoes) are a good place to start! Also make sure you have the best running socks and best running shoes.

Buffed Trail

A smooth, runnable off-road trail, with few obstacles and typically over rolling hilly terrain, as opposed to steep, tricky rocky, muddy or uneven terrain.


A trail running race with your dog! The dog is attached to their human via a special harness and you run the race as a team with your beloved pooch! REI sell a nice range of these canicross-specific harnesses.

Chafing / Chafe

Where your skin rubs raw from either rubbing against fabrics (such as your running clothes) or other parts of your body. Most commonly found in delicate parts of your body, such as between thighs, under arms and on nipples! Make sure you have running clothes that fit you properly and minimize the risk of chafing


Another word for an Aid Station during a race, although generally a checkpoint does not promise a smorgasbord of goodies, it may literally be someone checking your timing chip or bib number at a certain point during a trail race.

Chicked/ Chicking

Getting overtaken by a badass female trail runner during a race 😉

Code Brown

A sudden urge to find a porta-potty or secluded hole in the ground during a run.


In a running context, usually used to describe a muscle cramp, such as your calf or quad muscle – painful and stops you in your tracks! Often a result of over-exertion and/or loss of vital salts.


Not a term exclusive to running, but very important to understand and manage as a runner. Make sure you have appropriate means to carry water and replace vital salts when out running, to help reduce the risk of dehydration. These posts are a good place to start: Race Vests (running hydration vests), Soft Flasks, Saltstick salt tablets – stop muscle cramps.


Did Not Finish. Some races are just not meant to be, we live and learn, and come back stronger next time.

DOMS (Delayed Onset Muscle Soreness)

You know when you have a big training session, such as doing a longer-than-normal run? Feels good, right? Even the next day you feel ok, and rather pleased with yourself. But then…. Day 2 post-run – GAH! Those quads/hammies/calves ache like crazy! Yep, that’s DOMS, it takes a while to kick in.


Running from home (usually via a road/pavement) to the trails. Door-to-trail shoes are designed to be comfortable on both hard surfaces and moderate trails, for these situations – and are also great for running on mild trails, such as in city parks.

Fartlek Training

Speed training (translated from the Swedish term ‘Speed Play’) where you vary your pace between fast and slow at varying intervals, for example, running fast and slow between park benches or trees during a training run. Fartlek training makes speedwork a bit more interesting than fixed distance/time interval training.

Fast and Light

The principle of carrying a minimal amount of essential kit on a trail or mountain adventure, to enable you to move quickly and efficiently over off-road terrain. There is a fine line between having enough kit and being underprepared, so it takes a level of skill and experience to make sure you are adequately prepared with the right safety kit (such as enough clothes) when playing out in remote / potentially dangerous places.

Fell Running (aka Hill Running)

Originating in the UK, Fell Running is off-road running, however often does not involve running on defined trails. It’s common for Fell Running races to involve simply running up and over a hill (or up and down again) via whichever route you choose. This often means you’re running over bogs, scree, heather and other scrambly terrain, so it can get pretty messy and technical!

FKT – Fastest Known Time

A speed record on any given route. FKTs are getting popular amongst elite and fast trail runners, who seek out epic challenging routes and aim to complete them in the fastest recorded time, typically supported by witnesses and GPS data. There are no defined courses or rules, although people may set different times for doing a route (eg. circumnavigating a mountain or lake) depending on whether they did it ‘supported’ (with people meeting them at points along the way to provide food, shelter, etc) or ‘unsupported’ (where they carry everything they need themselves without outside assistance)


Gaiters are fabric (such as neoprene or parachute material) garment that wraps around the top of your shoe and ankle to keep debris out.

Gnarly Trail

The opposite of a Buffed Trail! Uneven, tricky, possibly slippery (eg wet roots and mud) or loose scree and stones to navigate.

Intervals / Interval Training

A type of speed training to help you train to run faster. Read our speed training post to learn more.

Loop Course

A running route that starts where it finishes, but doesn’t simply go out-and back – so you see as much different scenery and terrain as possible.

Mandatory Kit / Equipment

The items that race organizers stipulate you must have with you for your race, for your safety and to avoid being disqualified. This may include a minimum amount of food, water, clothing and emergency items such as a foil blanket, whistle and mobile phone.

Mountain Goat

Name used to describe an agile, speedy mountain or fell-runner! Also, a generic name for mountain-dwelling goats, such as the beautiful Chamois that can be found in the Alps.

MUT – Mountain Ultra Trail

An ultramarathon trail race, being held in mountain environments. Some of the World’s most famous ultramarathons, such as the UTMB, are MUT races.

Multi-Day / Multi-Stage

An ultramarathon race that take place over multiple days. Some require runners to be self-supported and carry a significant portion of their equipment, including all their food and clothing for the 3-6 days of the race.


My least favourite course, one that returns the way it came, so you repeat the ground you just covered, but in the opposite direction. The good thing about these is that you get to run down all the steep terrain you just climbed, but it works both ways!


A companion runner who may accompany an ultrarunner on certain sections of a race, usually for 100 mile races or longer. Common for North American ultramarathons, but rarely permitted in European races.

Poles (hiking or running poles)

Lightweight hiking or running poles are usually foldable so they can be stored in a Race Vest when not in use. Very popular with mountain runners in Europe, and gaining popularity for mountain running races in North America.


A one-way running route or race, i.e. one that finishes in a different place than where it starts, unlike an out-and-back or looped route. This is a great format for a running race where you want to travel as far as possible from A to B and not have to return to where you started! Examples of point-to-point races we have done include Transgrancanaria Marathon and Race to the Stones.


Transgrancanaria marathon review Most experienced trail runners find it more efficient both speed and energy-wise to adopt a fast hike for steeper uphill trails, rather than trying to run these sections

Race Vest

Also referred to as a hydration vest or pack, this is a specially-designed form-fitting backpack for runners, typically used when running more than a few hours through to multiple days at a time on the trails. They come in different sizes and male and female-specific fits. See Race Vests (running hydration vests) to learn more and read reviews of popular models.


A Fell Running (see above) route originating in the UK, where runners cover a set loop course involving covering a certain number of summits. Perhaps the most famous is the Bob Graham Round, a 106k loop in the UK’s Lake District that covers 42 fells and peaks with more than 8,000m of climbing and descent involved.

Run On Clouds

Brand slogan for unique running brand On Running. Their shoes include rubber ‘cloud’ soles. For more about On Running read ‘Best On Running Shoes’ and see the On Brand page.

Run Streak

Running every day for several days in a row. Read more about the Benefits of a Running Streak.


Narrow trail, usually only wide enough for one person at a time.


Mountain running above 2,000m of altitude over very technical terrain with a significant amount of climbing and descent. Traditional skyrunning races are typically between 25k and 50k long, and are often organized on a weekend involving a Vertical Kilometer race and an Ultra-distance skyrace.

Technical Trail

Like beauty or the spiciness of food, the technicality of a trail depends on who is contemplating it. An elite ultrarunner once told me that a certain ultramarathon course was not technical in the slightest. Maybe not for him, but I found certain sections were impossible to run!

A technical trail is usually one which is very uneven and steep, with tricky rocks, roots and loose footings to navigate. It may also involve semi-rock-climbing scrambles and descents – dangerous for the inexperienced and/or unprepared!

Tempo Run

A high-effort run intended to help you train to run faster. Read our speed training post to learn more.

Trail Dog

Loyal furry buddy who accompanies you on trail running and hiking adventures.

Trail Running

Aka the best pastime on Earth! Trail running means running primarily off-road, such as on dirt and forest trails. Taking up trail running changes your life! For inspiration visit our Trail Running website section, and read popular interviews with trail runners of all backgrounds and experiences levels.

Ultramarathon / Ultrarunning

An ultramarathon is running any distance greater than a marathon (26.2 miles). Ultramarathons can be run on paved surfaces, but are most commonly run on trails, where the ground is often softer underfoot, the terrain undulates, and the landscapes are more peaceful and varied.

Common ultrarunning distances are 50k, 50 miles and 100 miles, however the distances vary depending on the location and geography. For examples of ultramarathons we have run, have a read of our ultrarunning posts.

UTMB – Ultra Tour de Mont Blanc

A famous 100 mile MUT race in the French Alps, which follows the Tour de Mont Blanc trail to circumnavigate the highest peak in Western Europe, Mont Blanc.

Vert / Vertical Gain (and Vertical Loss)

How many feet (or metres) a running route gains, and therefore how much climbing (and descending) you would have to do on the route. The ratio of vertical gain to distance covered gives you an indication of how tough the route is, and how long it may take you. For example, a half-marathon distance with 1000 metres of gain will be relatively easier than a 10k with the same amount of gain.

Vertical Kilometer / Vertical Kilometre

Aka a ‘VK’ or ‘KmV‘, a point-to-point mountain running route that is less than 5km long, but climbs more than 1,000 metres (around 3,300ft) in that distance. VK routes and races are popular in the European mountain running community, and are only found in mountainous regions where it’s possible to climb this much over such a short distance. Read our summary of the Best Vertical KM races in the World to learn more.

Zero-drop running shoes

Zero-drop running shoes with no height differential between the heel and toe area. Traditional running shoes may have a differential of 10mm or more.


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