By the time Lizzy Hawker and Stephen Pyke staggered into Kathmandu’s national stadium on the morning of October 28, they had been running near continuously for three days.

Starving, deprived of sleep and more exhausted than most of us will ever feel, these two British endurance athletes had completed one of the world’s most gruelling challenges in long-distance running – a 188-mile trek from the base camp at the southern foot of Mount Everest down to Nepal’s capital, crossing some of the most inhospitable mountain terrain imaginable.

The two runners had endured temperatures as low as -10C and paddy fields filled with blood-sucking leeches, and had fought off altitude sickness. They also lost the third member of the team – Mark Hartell – who dropped out halfway, unable to keep up the pace.

But the pair said it was all worth it. By clocking a time of 3 days, 2hr 36min, Hawker and Pyke set a new world record for the course, smashing the previous time by nearly five hours.

And what makes this all the more remarkable is that the previous record had stood for more than seven years and was held by a famed Nepalese mountain runner called Kumar Limbu, running on home soil and phsyiologically better adapted to the conditions than Hawker and Pyke, both amateurs, could hope to be.

The trail is notorious among runners and locals alike. Many an intrepid group of runners has set off with glory in mind only to beat a weary retreat or to be rescued from near certain death, suffering from the combined effects of cold and exhaustion.

When the British pair completed the final stages through the city’s gridlocked and smoggy streets, they were greeted like heroes with a police escort that parted the traffic for them. At the finish they were met by a Nepalese television crew, though it was as much as Hawker and Pyke could do to stutter a few breathless words.

Since departing from their start point at 17,800ft just after dawn on the previous Thursday, the pair had climbed and descended the rugged terrain at a steady running pace. For food they survived on little more than hot soup, tea, glucose gel and tsamba porridge – a Tibetan dish made from barley. “Even if someone breaks the record tomorrow I won’t be doing that again,” said Pyke.

For decades local sherpas have slowly negotiated the treacherous climbs and descents of the trail from Everest base camp to get messages from mountaineering expeditions to Kathmandu and the outside world.

But it’s only in the past 25 years that outsiders have tried to run it for sport, and few have finished. Richard and Adrian Crane, two Britons, were the pioneers of running expeditions through the Himalayas in the early 1980s when they first mapped out the route. Then in 1987 two British women, Helene Diamantides and Alison Wright, completed the course in 3 days, 10hr 8min, and it was their effort that led to Guinness World Records recognising the run.

To prepare for the race, Hawker, Pyke and Hartell (or Team Montrail as they are known through their sponsors), spent several months running 70 or 80 miles a week on the hilly terrain around the Pennines. Then, five weeks before their attempt, they decamped to Nepal to train at altitude.

This served two purposes: to familiarise themselves with the severe conditions, and to acclimatise them to the high altitude to prevent altitude sickness (also known as acute mountain sickness), which is caused by exposure to low air pressure and can result in fatigue, stomach cramps and dizziness, not to mention death.

There were some things the team couldn’t prepare for, however. After a brutal 6,900ft descent at the start of the second day, the trio found themselves running along the edges of paddy fields into a driving monsoon.

“It was in a small forest that we noticed leeches on our ankles,” says Hartell. “A closer look revealed that our shoes where crawling with the things and on removing shoes and socks we found about 15 each per foot. Of course they inject an anticoagulant so we were dripping blood for the rest of the day.” Which all begs the question: why do it? None of the runners is a professional, but all have a passion for the sport. Hartell, 43, is an IT consultant who has won races all round the world; Hawker, 31, is an environmental scientist with the British Antarctic Survey and the world 100km champion; and Pyke (or Spyke as he is known), 42, is a research engineer with Rolls-Royce and a road runner.

“Lizzy, Spyke and I share a passion for running in beautiful and inspiring places,” says Hartell. “What better than to run from the roof of the world – surrounded by soaring snow peaks in the crisp early dawn and to submit to a mini-adventure.

“We knew the challenge would be tough – personally, and with hindsight, I should have prepared better for the mental lows that accompany sleep deprivation and exhaustion. It’s so easy to get ‘down’ and be defeated and I should have been stronger. We are, however, contemplating our next mini adventure in the Cordillera Huayhuash [in the Peruvian Andes] in early 2009.” Mini-adventure? Yeah, right.

How to take on a mountain

To find out more about just how gruelling the run was, read Mark Hartell’s blow-by-blow account at tinyurl.com/39aeps

If you’re still interested in this brand of extreme mountain marathon, you should start by fell running, otherwise known as hill running. The website of the Fell Runners Association (www.fellrunner.org.uk) contains information on races and links to finding a club

One of the biggest challenges facing any mountain run is coping with altitude sickness, which can begin to strike any time after 7,000ft and is often brought on by ascending quickly. The comprehensive website www.high-altitude-medicine.com explains just how to diagnose and treat the condition

A number of races take place every year in the foothills of Everest, including the Himalayan 100 Mile Stage Race, which is run over five days. See the organiser’s website for more information (www.himalayan.com)