PAULA Radcliffe can collect upwards of GBP500,000 for winning a marathon on smooth urban streets, so what price a victory over the same distance on the world's toughest terrain, racing up and down nearly 18,000 feet?

The 42.195-kilometre Zegama-Aizkorri mountain marathon tomorrow in the Basque country is one of eight events on the Buff Sky Running World Championship series. First prize is GBP684.

Despite this, things are looking up for those intrepid souls who think a marathon on the flat is for wimps. A world series and even modest cash represents progress.

Scotland's former world champion, Dr Angela Mudge, counts a Swiss raclette cheese and a voucher for flowers (unredeemed) among recent prizes, though Rob Jebb, a BT lineman from Kendal, admits to a GBP1700 prize for winning a race in last year's world series.

"Before, a regular top prize would be a GBP30 sports shop voucher, though I did once collect GBP150 at Grassmere sports, " he said, "but hillrunners don't do it for money."

Clearly not. Mudge is the world's most highly-qualified sports masseuse. She has a first class honours degree in chemistry from Stirling University, a Phd and MSc, but she has now qualified in sports massage because it appeals more, and most pertinently allows her to indulge nomadic instincts. "I spent two and a half years in a lab, and didn't like it, " she said. "Doing a Phd lets you be your own boss, time to pursue other things. I'm not career-driven."

Mudge, who is based in Alva, has been teaching athletics in a Dunblane primary this week, collects samples for Scottish Water, has worked for the Scottish Executive, and in recycling, plus numerous laboratory jobs. But the hills are where her heart lies.

She travels the world, often alone, cooking and eating under the stars, and scraping ice off her tent in the morning to keep costs down in order to indulge her peaks passion.

Short-listed for the extreme sportswoman of the year award, by an electoral college including Muhammad Ali, she declined to accept the all-expenses paid trip from New Zealand to London.

She preferred to run in the Southern Alps, and said she did not possess a little black number to wear. She added that she would have been running around the Albert Hall like a tourist, collecting autographs from nominees in other categories: the likes of Cathy Freeman, TigerWoods, Luis Figo, David Beckham, Rivaldo, Sir Steve Redgrave, Lance Armstrong, Michael Schumacher, Shaquille O'Neal, Pete Sampras, Venus Williams, and Ian Thorpe.

Truth is, 35-year-old Mudge is equally bright in the extreme sport firmament, but says: "I don't regard it as extreme."

At last, though, there's some real recognition. Mudge and Jebb are running in Zegama tomorrow in a sponsored team, first glimmer of a commercial future for mountain running.

Mudge has been British cross-country champion and four times British fell-running champion. She has individual and team World Mountain Running Trophy gold medals and two European Grand Prix titles. Now she has been signed by Team Saab Salomon Adventure Racing in an attempt to help them win the world team title. The company has an annual budget for the team of, "well into six figures".

One female is needed in each quartet, and Mudge has joined Jebb who dominated last year's Sky Running World series, Borrowdale's Simon Booth (current UK fells champion) second last year to Jebb, and Lancastrian Nick Sharp, who was fifth. All have made regular podium finishes in Scottish races, but without a woman, the squad can't qualify for team honours.

Zegama is one of eight races, from which the best four finishes count. The others are in Mexico, Switzerland, Japan, Italy (twice), Andorra, and culminates in the Kinabalu Climbathon, in Malaysia.

Trails, glaciers, and moraines are typical terrain. Before one event on the Swiss-Italian border, a runner fell into a crevasse and died, though races themselves are not known to have claimed lives.

Continued participation is perhaps a second miracle for Mudge. She was born with both feet facing the wrong way and had them in plaster until she learned to walk. In 2004, she was set to sign with Saab Salomon, but had to undergo reconstructive surgery, spending two months on crutches.

"I'd worn away all my knee cartilage - more to do with my running style than the sport itself, " she said. "I was running on the bare bone of my femur, so the surgeon drilled holes, which stimulates scar tissue."

Even months after the operation she was allowed to run for only 10 minutes. "I don't mind running uphill, but I might skip Kinabalu, which is up and down, and 'down' is about 7000-feet - too much jarring. It will depend on how we're doing in the series. I'll certainly miss the Swiss race because it is the week before the World Mountain Running Trophy in Turkey."

She has done Kinabalu three times, winning twice and making such an impression that the organisers agreed to equal prize money for women. The 21k (half marathon) course usually takes backpackers two days. The men's record is 2:42.07. Mudge does it in just over three hours.

The trail climbs through several climatic zones from steamy equatorial jungle to freezing tundra, and tops out at a lung-bursting 13,300 feet.

This was the mountain on which 10 British squaddies got lost for several weeks. They clearly neglected the priestly pre-race ritual of slitting the throats of six fighting cocks, designed to appease the spirits which haunt the sacred peak.

"This Sky Running series will be living it up, " says Mudge, "a bit posh for me: flying, travel by car instead of bike and carrying all my gear on the back, and staying in hotels or B&Bs . . . I'm going soft in my old age."