If you visit Chamonix, the French mountain town nestled at 1,037m above sea level, in the last week of August, you’ll find yourself surrounded by thousands of trail runners from across the globe. They’re here to run one of the seven races put on by Ultra-Trail du Mont-Blanc (UTMB) over the course of seven days, culminating in the big one – the ultramarathon itself.

At 105 miles long, looping all the way around Mont Blanc and passing through three countries, it’s not so much the distance that makes it a challenge – although that’s one major part of it. It’s more the five-figure elevation gain over those 105 miles. A total of 10,000m – higher than Everest – results in the ultimate physical test that, for a select group of ultrarunners, is hard to resist.

In that spirit, I was not in Chamonix as an observer: I was there to experience everything the Trail du Mont Blanc loop had to offer by taking part myself.

Aside from the challenge (perhaps ‘ordeal’ is more appropriate) that hovers on impossibility, the Alpine scenery is a major draw. When you’ve been training in the south of England, where the biggest hill nearby tops out at a miniscule 180m, craning my neck at the vertiginous peaks that surround the town makes me feel woozy. What on earth have I signed up for?

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The route takes runners through France, Italy, Switzerland then back into France. British ultrarunner Tom Evans, who came third in 2022 and sadly had to pull out of this year’s edition at 80km due to a medical emergency, told me before the start that there’s no other race quite like it. “It’s the Super Bowl of trail running. For a week, pro trail runners are treated like A-list celebrities. It’s bonkers.” His favourite part of the race is summiting Grand Col Ferret, at the 100km mark. “By the time we get there, the sun is rising. It’s incredible.”

On Friday afternoon, hours before the 6pm start, I try to stay horizontal in the shade of a hornbeam. My eyes cannot help being drawn to the Mont Blanc massif, the wind whipping puffs of snow off the distinctive granite shards. My anxieties start snowballing. Have I trained enough? Have I chosen the right shoes? Have I eaten enough pains au chocolat?

American former elite trail runner Topher Gaylord, who took part in five editions of UTMB including the inaugural 2003 race (this year is the race’s 20th anniversary), describes UTMB as a “transformative experience” in Doug Mayer’s book, The Race That Changed Running: “You have the opportunity to experience all the emotions of life in a single day. UTMB delivers you back to Chamonix a changed human being.”

As the runners eventually cram behind the start line in the packed Place du Triangle de l’Amitíe, I zone out, wondering how this might change me. The sound of the race anthem, Vangelis’s “Conquest of Paradise”, rouses me from my thousand-yard stare, and the spectators lining Chamonix’s streets excitedly yell “Allez! Allez!” as we stream past. The epic journey back to this very same spot, days later, has begun.

The first 30km takes us through the resorts of Les Houches and Saint Gervais, where the crowds approach levels of freneticism rarely seen in the UK. They are, it’s safe to say, buzzing – whooping hoarsely, high-fiving runners – and you cannot help but feed off their fervour.

We’ve covered one climb by now, but it’s a mini compared to the maxis on the horizon. When we begin the first serious ascent, up the fiercely steep, slab-strewn Notre-Dame de la Gorge, I’m unprepared for the Tour de France-worthy spectators crowding in on us, roaring, whistling, waving flares. There’s even a man wildly revving a chainsaw. It’s truly spine-tingling – I find myself yelling along with them, adrenaline sprinting, elevating my heart rate to 180bpm.

The route sticks mainly to the Trail du Mont Blanc, which 10,000 hikers tackle annually, taking 10 days on average to tour the massif. All the way round, you can sense Mont Blanc on your left, rising up to pierce the clouds, unmoved by your efforts to circumnavigate it.

In the darkness, there’s time to consider what I am doing running on a mountain instead of safely asleep in my bed. But that’s the point of UTMB – to see exactly how far you can push your mind, body and spirit into unheralded levels of discomfort. Shuffling through the fresh night air under a sky glittering with stars, with the mountainous skyline pitch black against the cool navy sky is humbling and strangely calming.

By dawn, having crested the highest point – the rock-laden Col des Pyramides Calcaires at 2,567m – I’m feeling more tired than inspired. I’ve made it to the Italian resort of Courmayeur at 80km, where the advice at the bustling aid station is to get in and get out quickly, as so many competitors call it a day here.

It’s tough to leave knowing we’re heading skywards again. But at the top of the ascent, with Rifugio Bertone marking an undulating section that tracks the valley below, the rising sun colludes on a view that makes me choke on my sickly-sweet energy drink.

Grand Col Ferret looms in the distance, and the summit marks our journey into our third country: Switzerland, with verdant fields of grass, the gentle chimes of cowbells (we even have to stop to let a trio of cattle leisurely cross our path on the aptly named ‘Bovine’ climb) and shady, pine-scented forests that make hiking the endless switchbacks in the afternoon sun marginally less painful.

By this point, runners, including myself, are flaking. I pass many bent double resting on their running poles, sprawled on the soft pine needles or even vomiting Coke at the side of the trail. I check they’re OK as the silent march upwards continues. Eventually, another summit arrives, then another, and before I know it, dusk has swept over us for the second time. I’m on the way up to La Flégère, the final peak, stumbling over rocks and roots like a zombie taking their first steps, desperate not to roll an ankle so close to the finish.

Following a winding downhill, a peacefulness sweeps over me. The only sound is the flowing glacial streams, the tapping of running poles and my ragged breathing. The finish is visible. Achievable. After 34 and a half hours, I don’t have to run any more. My battered body has carried me around, my doubts extinguished. This thing I secretly thought impossible, was possible.

I collapse in a chair, consumed with relief. Around me, others do the same, a collective understanding that we’ve pushed ourselves to the precipice of mental and physical exhaustion and made it through without careering into the abyss.

As the naturalist John Muir said, “The world’s big and I want to have a good look at it before it gets dark.”

I had more than a look (while it was dark, too). And it was worth every agonising step.

More information

To find out how to enter UTMB 2024, visit utmb.world

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