Forget the brief heady thrills of freestyle acrobatics or the adrenaline rush of your first black run. For the true skiing connoisseur, there are few bigger challenges than the Haute Route, the ultimate ski tour, which winds for about 112 miles through the highest, most dramatic peaks in the Alps.

And, boy, does it make you earn your downhill kicks. More than 70% of the route is uphill, climbing 28,000ft during the six or so days it takes to climb, ski and hike from Chamonix, the French home of Alpinism, to Zermatt, in German-speaking Switzerland.

“Ski touring” may sound genteel but, as I was about to find out, names can be deceiving. For the hardened ski tourer (or ski mountaineer, which sounds more fitting), the Alps begin where the pistes and ski lifts end. According to these uncompromising souls, if you want to ski down a high Alpine valley untouched by anything but the odd sure-footed chamois, you should earn it first by getting up there under your own steam.

The Haute Route was first completed on skis in 1911 and was originally devised, naturally enough, by a handful of foolhardy Brits. First christened the High Level Route, it is now most widely known by the French translation. You can attempt it between March and early May, when the snow bridges over the many crevasses have (hopefully) settled; the weather is a bit kinder and the days are long enough to allow you to cover enough terrain. Still, only about half the skiers who set out complete the course. Did I have what it takes?

The first step was to assemble the right kind of kit to give myself a sporting chance. I was keen to see how little could be carried safely in the mountains for a week. Olly Allen, a British mountain guide for Mountain Tracks, which helps skiers along the route, watched as I flourished the items in my rucksack the night before departure. His response to each was simply “yep” or “ditch”.

Touring skis are light yet wide enough not to sink in deep snow. They have a special binding that allows the boot heel to lift when moving uphill and lock down on the descent. For travelling uphill, I would use “skins”, long strips of glue-backed nylon brush material that stick to the base of your skis so you can slide smoothly upwards, but offer enough grip to stop you sliding back. When the way was particularly steep and icy, metal brackets called “couteaux” would be added to the ski-bindings, providing crampon-like grip under the ski. Add in an avalanche transceiver, which helps find people buried under snow, an avalanche probe, which can be used to poke into a snow pile to search for equipment or victims, an ice axe for vertiginous sections, a snow shovel, climbing harness, crampons and adjustable ski poles and the only luxury I had room for was a toothbrush.

We headed out every morning before dawn. I soon realised there was a reason for early starts in the mountains in springtime. Having got to grips with the skins and couteaux on our first long, zigzagging 1,000ft ascent, we arrive at the Col du Passon, above the Argentière glacier in the Chamonix valley, late in the morning. It’s on with my crampons and out with the ice axe, to try to get a firm grip in the snow above me. By this time, though, the sun has turned the snow to wet sugar. Soon every step on the 45-degree slope finds me sinking thigh-deep into the snow — benignly known as “post-holing” — sapping the strength of all but the ridiculously fit and light.

Stamina is as important as skiing ability but humour helps when all else fails. It’s amazing how a tidy skiing style can fall apart when faced with a 45-degree incline, which is covered 3ft-deep in crusty, sugary snow and bathed in a “flat light” that hides any troublesome ruts or gullies. Allen weighs just 9½ stone, is nimble, and is a member of the British ski-mountaineering team. Some 4,000 people start the Haute Route every year, but Allen reveals that bad weather means he has yet to complete it, despite four attempts. It’s a reminder that mountain weather is fickle and unforgiving.

As I acclimatise to the thin mountain air, the rhythm of “skinning” up for the first col of the day in the blue light of dawn becomes as natural as breathing. By the fourth col of the day, however, the breathing is a little more laboured and thoughts are not quite so poetic. By now I’m reduced to chomping snow to avoid dehydration — a bad idea, I’m told, because it’s full of Saharan grit and germs blown in on high-altitude winds. I pass a German skier, who has stopped to catch his breath, and summon a hearty, “Can’t be far now.” An Eeyore-ish riposte says it all. “Vell, ve have no alternative.”

The route is peppered with joyful sweeps down pristine snowfields, but these seem all too fleeting. By day four we’ve climbed 18,000ft, topped eight cols and skied, climbed, skinned and trudged for 75 miles. On the sixth day, I’m faced with an agonising 50-degree icy slope up to the Col du Mont Brulé. I’m front-pointing: kicking the crampons’ toe spikes in hard enough to stand on while hacking with my ice axe and shortened ski pole above to keep my balance. Every limb is aching, and trying to pull me from the face is the lumbering weight of my backpack with skis strapped to it.

Despite the cold I’m wearing only a base layer and I’m sweating with the effort of maintaining the rhythmic thunk, thunk of kicking steps into the icy snow. The thin air at 9,900ft makes breathing more laboured and a thumping headache doesn’t help. Somehow I summon up enough energy to continue over the Col de Valpelline, but there is one more challenge to come.

Beneath the imposing peak of the Matterhorn, a river of glacial ice inching over a rocky cliff had dropped huge chunks of ice, called seracs, onto the slope above us, just hours before. If it’s possible to ski and tiptoe, we do it, scared to bring ice boulders down on our heads or set off an avalanche. We make it through unscathed, only to discover our longed-for glorious descent into Zermatt will be scuppered by a distinct lack of snow. We resign ourselves to a long hike instead, and several hours later we’re barefoot, reeking but triumphant, sipping celebratory beers in a Zermatt bar. Someone asks where we have come from, and we tell them — Chamonix. And on foot.

ESSENTIAL KIT FOR SKI TOURERS

Ski touring combines uphill skiing, walking and climbing over several days and requires lightweight, specialist kit

1 Backpack Will Robson carries one made with Kevlar, which is very strong and prevents ice axes and other kit from ripping it

2 Base layer A tight, long-sleeved top made of merino wool is warm, light and helps wick sweat away from the skin

3 Avalanche transceiver Attached to Robson’s shoulder strap, it emits a signal that can be used to find anyone who is lost

4 Ski poles They are telescopic, so their height is easily adjustable — important for skiing across slopes when one needs to be shorter than the other

5 Climber’s harness Allows skiers to rope together to cross dangerous glaciers, or to throw a line to anyone who falls beyond reach

6 Touring boots Robson’s Scarpa boots are rigid enough for skiing and have a rubber tread, like a climbing boot, for walking

7 Touring skis (not seen) These are light and wide, to stop them sinking into snow. Strips of a nylon brush material, known as “skins”, are attached to the bottom for skiing uphill. The fibres are smoothed down when you push uphill but will bristle, to provide grip, if you slip back