Rating by Distance, Elevation and Technical Difficulty


 Trail running is a sport that involves running or walking in a outdoor environment on a natural terrain, taking advantage of the geographical features offered by each region (usually mountains, deserts, forests…) and following a logical path that allows us to discover the region. Trail running encompasses very different practices, depending on where we run, the distance and the characteristics of each region.

iancorless-orgp1050496trofeokima                                 884A9949_TJOHNSON

(c) Ian Corless Troffeo KIMA                                                (c) Tanner Johnson Western States 100


It’s important to know that Trail running is a sport played outdoors, in the nature. That implies a difficulty of classifying competitions as each race will have its peculiarities. We will never find an identical race to another and even the same race may well change from one edition to the next, as specificity and difficulty of the game is given because the mountain is a living being, that is changing and it is different at each place and at all times of the year.

Two races with the same elevation and distance can be very different from each other, either by the type of terrain, the climatic conditions or the conditions of the mountain at the time, or the different surfaces, such as snow, mud or a dry floor.

And although each mountain race, by elevation, weather, terrain, technicality, kilometers and more factors is almost impossible to establish a classification. Trail runners mostly think about physical capacities (“I can run 20km, 80km or 200km” or “I can make 4000m elevation…”) but rarely they do think about the difficulty (“it demands some climbing, it demands to know how to put the feet, rocks, snow…”) the experience (“need to navigate out of trails, need to use and know to use extra gear to protect myself because is a storm, need to stay on the middle of a mountain for some hours waiting for a rescue….”) and the exposition (be injured here is difficult to evacuate, “if I fall from here I can die…”)

We think it is very important all the trail runners to understand that Trail Running is not just about distance and elevation but about technical skills and experience. Our goal is not to make a classification of the races but make the runners understand the technical notion on races to be safer and to not go where they have not the technical capacities.

We were thinking on a label of races on difficulty/exposition. As there is in mountaineering a system to provide guidance if you have enough experience to do a route(PD, AD, D, MD, ED) we design a label system for trail races to tell people what they may expect.


The facts that differecncy every trail race can be grouped on 3 axes:

  1. Distance: kilometers of the race
  1. Elevation: ascent meters and downhill meters
  1. Technicality and Exposure: Exposure, altitude and technicality of the terrain. Considering the risk of injury or die, the technical skills to progress on every terrain, the self-reliance needed to be on safety by oneself.

 We can study the distance on a metric system (distance on kilometers) or on a physiological way on the duration of effort:

– Short: need of a strong contribution of the anaerobic metabolism (mainly lactic, but also alactic), the intensity is above and not lower than the anaerobic threshold. Maximum time: from few seconds to one hour.

– Medium: need of a mixture of aerobic and anaerobic metabolism, up, but not higher than the anaerobic threshold, or between the aerobic and the anaerobic thresholds. Time: between one hour and few (3-4) hours (we have to decide considering the aerobic power/time relationship).

– Long: need only the aerobic metabolism, always under the aerobic threshold. Time from 4 hours, but less than 16 hours.

– Ultra-long: mean intensity always under the aerobic threshold, but race long enough to reach a minimum level of sleep deprivation (that affects brain and cognitive functions). So, considering a mean of 8 hours of daily sleep, we can define “sleep deprivation” when the performance lasts more than 24-8=16 hours.


Lavel distance time Examples
short 1-19km 20’- 1h Vertical Kilometers, Mount Marathon, Tjon Dixence
middle 20-49km 2-4h Dolomites SkyRace, Zegama, Ultraks, Sierre Zinal
long 50-100km 5-16h 80 Chamonix, Transvulcania, The Rutt
ultra more than 100km > 16h UTMB, Hardrock 100, Diagonale des Fous
Stages races multy day race Transalpine run, transrockies, 4 trails

We consider the elevation on meters or feet, taking the elevation gain in the case the race have the same drop on uphill and downhill, and specifying the uphill and downhill elevation on the case the race is A to B.

We can difference:

– Uphill race: only positive elevation: includes Vertical Km, Opp races, Pikes peak ascent

– Downhill race:       only negative elevation

– From A to B race: Start and finish line not at the same point, so different + and – elevation. Exemples:    WS100, Valmalenco Valspochiavo,

– loop race: Start and finish on the same point, so same + and – elevation: examples: UTMB, Zegama, KIMA…


 Taking the example on mountaineering label for alpine routes (PD to ABO) we make a label on trail running races:

Level Tecnhical skills Exposition Examples
I – EASY easy terrain, not need to use the hands. Clean trails, on outdoors or low mountain.  no risk or small injuries Sierre Zinal, Western States
II- INTERMEDIATE easy terrain, not need to use the hands. Some rocky or mountain trail parts, need to have a “randonée” or low mountain knowledge. Risk of injuries and need to be self-relianced on low mountain (wait to be evacuate in case of accident, not get lost on non visibility,know to  follow trails, know about storms…) UTMB, Zermatt Ultraks, Giir di Mont, Zegama
III- INTERMEDIATE dificult terrain, rocks, snow, go out trails. Need to use the hands.  Need to have a middle – middle – high mountain knowledge. Risk to get injured or seriously injured. Need to be in autonomy in hard mountain conditions. Diagonale Des Fous, 80 Chamonix, Dolomites Skyrace, Hardrock 100, The Rutt
IV – DIFFICULT dificult terrain, steep rocks, hard snow, small scrambling and ropes use. high mountain knowledge. Use of Risk to get injured or seriously injured. Need to be in autonomy in hard mountain conditions. Sentiero delle Grigne, Elbrus race
V – DIFFICULT Dificult terrain, glacier, rock scrambling, up to III climbing grade. Need a high mountain knowledge. Use of crampons or technical gear. Risk to get seriously injured or die in case to fall. Need to have knowleges on hight mountain and be independent to make himself safe in all conditions. KIMA, Lenin race, els 2900, Tromso SkyRace

Other factors can influence on the T label:

– Distance on exposed terrain, the fatality in case of fall.

– A long way or difficult access to evacuate in case of DNF or accident.

– A low number of aid stations or controls, the needed of navigate and be autonomy during long periods on the mountains.

– the quality of the terrain, as lose rocks, ice snow…

– Weather conditions on the race spot, as average on the dates and area.

– Mountain knowledges are not just about the altitude: High mountain (glacier) can be at 1000m on Scandinavia, 3500m on the alps or 5000m on Himalayas or US.

Captura de pantalla 2015-04-02 a les 18.06.44


Trail running is a mountain sport, Altitude should be considered starting from the classification proposed by Bartsch and accepted by the UIAA:

Altitude From m To m AMS lavel
Light Sea level 500 No no
Low 501 2000 Usually no no
Medium 2001 3000 Possible no
High 3001 5500 Possible/probable specify “High altitude”
Extreme 5501 8848 Probable specify “extreme altitude”

AMS: Acute Mountain Sickness Acute mountain sickness can progress to high altitude pulmonary edema (HAPE) or high altitude cerebral edema (HACE), which are potentially fatal.

Also in high altitude the recovery time it decreases, the decisions taken is less lucid and we have less precision on the movements.


The organizers must be the ones who decide the label of the race, in function of the technical and exposed facts of the track. And communicate for the safety of the athletes, and don’t overestimate the difficulty to don’t make the athletes confused on other races more technical.

The athletes must understand which are their technical capacities and experience to take part on a more or less technical race. And to train and improve this capacities on training before taking part on a more technical race (without counting the distance and elevation facts)

Federations must control that the races under his calendar are well labeled. A over-label can make misunderstanding and confusion and affect the safety of the racers.

The situation today:

Alpinism and Athletics are on the schema to situate the label and other disciplines.

Captura de pantalla 2015-04-02 a les 18.07.00Alpinism / Alpinrunning: a global sport, not on Trail running label, label used is the UIAA (PD,AD,D,TD,ED)

Trail Running: a global sport, running on the outdoors on natural terrain.

Inside we can find some disciplines:

Skyrunning: On technical trails, altitude and hight mountains. from level I to V

Fellrunning: On technical trails, normally off trails on rocky and grass terrain, specific from UK. From level I to V

Vertical Kilometer: A Only uphill race. the technicality can be from I to V.

Mountain running: On easy trails on outdoors. Level I of technically.

Urban Trail / City Trail: On urban spaces, on artificial terrain, with elevation and artificial obstacles. Level I of technicality.

Athletics: a global sport, running on the outdoors or indoors on artificial terrain. Only Cross country is on natural terrain. Technical label will be 0.


 Kilian Jornet Burgada, Thanks to the collaboration of:

Giulio Sergio Roi, Doctor specialized in altitude and mountaineering

Fabio Menino, Journalist, sport analist

Marino Giacometti, ISF president

Carlos García Prieto, ITRA secretary

Joe Grant, Runner and representant of trail running athletes commission, 

Christophe Boloyan, Directeur de la Chamoniarde

Download PDF

link to Alpinism – climbing – scrambling grades

  1. Hi
    This is a very pertinent aspect of our sport but I am not sure that every thing should be classified.

  2. I like the ideas here. I think the same group of people would have to rate all the races if there hope for some consistency. Unless you could really spell out the details to enable any race director to label the race themselves.

  3. Ara falta que la gent i els organitzadors ho tinguin en compte! La muntanya es un medi natural i cambiant i MAI s’ha de subestimar i deixar de respectar.
    *When i see you on the mountains SMILE and i say HELLO ! 😉

  4. Molt bó I objectiu per posar una mica de ordre i evitar accidents perque no es extrem ni bogeria es disfrutar de la natura i cada persona ha d’entendre i asumir les seves limitacions aixi com els limits que no es poden traspassar a la natura.👏👏👏☺

  5. Hi,

    Thanks for taking the initiative !

    Some typos I noted:

    regiona => region

    Trail running it encompasses => Trail running encompasses


    And although each mountain race.. classifiction => a piece is missing

    but rarely they think => but rarely do they think

    all the trail runners to understand => all the trail runners understand

    We think is very important => We think it is very important

    to be more safe and to don’t go => to be safer and not go

    We was thinking on a label => We were thinking about label

    As in mountaineering exist a system that can guide yourself if you’re experimented to do a route (PD, AD, D, MD, ED) and we design a label system for trails races, to don’t see in adapted people on technical trails and to have a prevention of what they will find. => As there is in mountaineering a system to provide guidance if you have enough experience to do a route, we design a label system for trail races to tell people what they may expect.

  6. Hi Kilian, This a a great system, especially for events. Here in Australia, our consultancy, Adventure Types, has also created a proprietary technical system for rating trails, Trail Score. However rather than concentrate on rating trails for events as you have, we concentrated on recreational (non competitive) grading of trails for runners. That is, creating a system akin to that seen in skiing, mountain biking and walking ratings for trails where the end user is of a recreational nature. The aim is to have councils, regions, tourism authorities use our system, graded by registered assessors, to create a suite of trails for both promotion /marketing of a region’s attractions for trail runners and for land management (i.e. directing runners onto assessed and certified trails, rather than using trails that land managers / parks authorities would prefer they stay away from or are closed.

    See the link / pdf here for how we make our grading:

    Obviously this Trail Score system would not be appropriate for competitive events as realistically it is a grading system for trails of up to 30km or so – beyond that they are all rated Black / Epic anyway, given the recreational nature / one day usage assumption.

    Would be interested to know what you thought of this, in the context of a more tourism orientated context.

    We have had several tourism authorities and alpine resorts empty the Trail Score rating system here in Australia, and we are working to take the rating system overseas as a tourism enabler (which can actually work in tandem with an event system like the one you have created, as the Trail Score system is about enticing runners to trails of their own accord with some guidelines, at any time, rather than at a specific event, thus it ‘in-fills’ the usage of trails in between events.

    We had wanted to discuss this Trail Score concept with an international authorising body (ITRA?).


    Adventure Types

  7. Good initiative! However I recommend using a better translation because reading through this is very tiring and distracting from the true essence. Technicality and exposure are best described in multiple frases in stead of a scale.

  8. You need a third axis – climate. Simply put, humidity weighted to temperature. Extreme (hot/cold, dry/wet) climates are much harder to run in than moderate ones. IMHO, it’s harder to run in wet hot than dry hot.

  9. It’s a good start, however not all the races are made in the mountains. We need another another category for hot and humid climate races like Jungle ultras or desert ultras, self support, semi self support, also the navigation issue….
    Thank you for the initiative.

  10. Excellent start for an all-encompassing rating!

    Here is a simple one that we’ve been using for the last 5 years in South Africa – developed by Owen Middleton.

    Trails are basically rated on:
    1. Terrain difficulty (easy or tricky?)
    2. % single track/off-road to on-road (how much on difficult terrain?)
    3. Route severity (how steep?)

    I use it on my blog ( for classifications and use it when they classify their races.

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