Mountain Safety and Rescue

Trail running

Well-known for its great vertical amplitude, Chamonix offers terrain that can be wide and easy to roll on, steep and technical, narrow and challenging. For the past few years, Chamonix has attracted trail runners from around the world, making it today a leading destination for trail running.

Trail running in the mountains

  • Terrain
  • Conditions and seasons


Trail running in the mountains, and particularly in the Chamonix valley, can be very different from the classic activity which takes place in lower mountain regions.

Some routes go through uneven terrain and have steep ascents and descents, which can take you by surprise and take longer than expected. Points of reference will be unclear and it will be a lot harder on your muscles. 

Trail runners have to be realistic about their physical form and their muscular ability to absorb the mountainous terrain. Poles are highly recommended. Trail runners have to check and manage their timings and adapt their food intake.

Conditions and seasons

The mountains are affected by the seasons more than elsewhere. Some routes are only accessible in summer or autumn. 

At the start of the season (until mid-July depending on the altitude), many persistent névés can make progression difficult or even impossible and dangerous. Many snow bridges formed over torrents and streams become fragile. 

The weather changes are sudden and sometimes extreme, such as winter conditions in the middle of summer. Trail runners will have to consider these factors and adapt their equipment accordingly.

They can find out about the snow conditions for their planned route from the High Mountain Office on

Many trail runners wish to take advantage of the bank holidays at the end of spring (April and May) to come and check out the different Mont Blanc Marathon or UTMB routes. This is often much too early: long sections at altitude are often still entirely under snow, which is often still hard. 

These passages are often impassable and dangerous. It is therefore imperative to check the conditions before leaving and to adapt your itinerary or give up if necessary.


From Servoz to Vallorcine, going through Les Houches, Chamonix and Argentière, 18 trail running circuits have been mapped down.

  • S route from 1 to 2 hours 
  • M route from 2 to 4 hours
  • L route for efforts lasting 4 to 8 hours.

A detailed trail running description was published and a specific sign system (numbers and 10 cm wide green strips) was added on trail marking posts.

The classification system refers to a number and a direction. All information and downloadable route descriptions are available on the valley website

Trail running off marked paths and Scrambling *

Perfect preparation

In addition to all that has been said above, trail running off marked paths requires infallible advanced preparation of the route so as not to find yourself in a precarious situation. That is to say, at the bottom of a lapies or lost between two rocky cliffs. 

There are mapping apps (Iphigenia, AlpineQuest, etc.) which allow you to locate and orientate yourself in real time. Using these will ensure a safe progression and will eliminate the need to improvise.

* Scrambling: Moving quickly in a rocky and steep environment off marked paths. This can include easy rocky ridges and very easy climbing.

Trail mountaineering


An up and coming sport, trail mountaineering (also known as Alpi-trail, Alpirunning or Alpinrunning) consists of moving quickly in a mountainous environment with all that the mountain involves: glaciers, rocky or snow ridges, snowy or icy slopes...

In the Chamonix valley, trail runners will quickly be confronted with a specific high mountain environment.

The equipment perfectly adapted to normal trail running becomes insufficient and is no use in the event of a fall, slip or snow bridges formed on top of crevasses giving way.

Learning about the mountain and technical skills begins on progressive routes, with a mountain guide or a competent partner.

Equipment and experience

You must therefore be equipped with appropriate mountaineering equipment and know the specific progression and rescue techniques:

  • Knowing how to walk in crampons on all types of snow and terrain.
  • Choosing the right length of rope to better manage technical passages.
  • Knowing how to perform a crevasse rescue in the event of a fall into a crevasse.
  • Being able to stop your own slide or that of your partner.

Altitude influences physical abilities and good physical fitness is no longer a guarantee of safety. Acclimatisation is essential to not feel the altitude’s effects.

In summary, it is essential to be in excellent physical condition, to be equipped with the appropriate mountaineering equipment and to know the specific progression and rescue techniques. Remember: NEVER GO ON YOUR OWN!

Mont Blanc Focus

  • A mountaineering route
  • Regulations and numbers
  • Weather forecast
  • Altitude sickness
  • Equipment suitable
  • Supervised Experience

A mountaineering route

The ascent of Mont Blanc (4810 metres above sea level) by the normal route is a mountaineering route and not a trail running route. 

The goal is to move quickly using lighter equipment. However, in no case should you deviate from the basic safety rules of mountaineering. We can’t all be Kilian Jornet…

Ascending in one day from the valley (one shot) intrinsically limits the time of exposure to risks. However, specific equipment and essential experience are required. Equipment suitable for trail running becomes completely insufficient and is of no use in the event of a fall, slip or break in snow bridges formed over crevasses.

The normal Mont Blanc route is a mountaineering route where several technical passages follow one another:

  • Crossing the Goûter couloir, threatened by rock fall (time management is essential, especially on the way back).
  • The ascent of the Aiguille du Goûter where there is a high risk of falling
  • The Dôme du Goûter glacier and the Col du Dôme where a lot of crevasses are hidden and where, in the event of fog, navigation becomes difficult.
  • The final and narrow ridge, arête des Bosses, which has sheer drops on either side and where getting tangled in your crampons is not an option.

More Info

Regulations and numbers

There are regulations regarding the ascent of Mont Blanc by its normal route. It is important to refer to them . 

Download the flyer

The PGHM, sometimes on patrol, will be able to judge the trail runner’s ability to go up and down in one go without a night in a refuge.

The frequent use of this route does not guarantee safety. It can even become problematic when there are too many people on the Aiguille du Goûter (due to recurring rock fall) or on the arête des Bosses (due to delicate or even impossible passing).

    Conditions météo

    In the high mountains, changes in weather can be abrupt and sometimes extreme:

    • In the middle of August, tens of centimetres of fresh snow can fall. The ascent or descent of the Aiguille du Goûter can become complicated.
    • The wind reinforces the cold, which you will already be feeling as temperatures can drop as low as -20°C. The jacket you wear for your daily jog on a cool morning will not be enough! The wind can also reach sufficient speeds for you to lose balance during progression on the narrow arête des Bosses…
    • A cloud can suddenly cover the top of the route, lowering the visibility to almost zero on the Dôme du Goûter glacier, on the Col du Dôme and on the summit ridge.
    • ...

    Altitude sickness

    Acute altitude sickness can affect anyone, even the most seasoned mountaineer or a trail runner with the VO2 Max of a chamois. Sport enthusiasts will see their physical and pulmonary capacities greatly reduced. 

    Altitude sickness can be very disabling or even fatal (cerebral oedema in particular). Acclimatising before the ascent of the Mont Blanc is imperative in order to avoid all effects linked to altitude.

    Equipment suitable for mountaineering

    Trail runners will obviously choose lighter equipment, suitable for mountaineering, without neglecting their own safety.

    They must wear warm shoes with high tops, suitable for wearing crampons. This implies no trainers. 

    They must have a pair of crampons with steel points. Nortec or Camp “ice master” type trail crampons should stay in the cupboard (with the trainers!).

    Supervised Experience

    Learning about the mountain and technical skills begins on progressive routes, with a mountain guide or a competent partner.

    For information, some mountain guides or professionals offer trail-mountaineering courses or ascents (Eg: Aiguille du Tour or Mont Blanc in a day).

    Quand les Yétis font du trail

    Les Yetis

    LeTrail en montagne
    Tout refuser

    Utilisation des cookies

    Ce site utilise des cookies dont certains sont necessaires au bon fonctionnement de celui-ci et d'autres optionnels. En savoir +

    Cookies optionnels :