ULTRA runner Shona Thomson is about to tackle her biggest challenge yet.

The Evening Times told last October how Shona is preparing to race along the frozen Tuul river in Mongolia.

She has previously raced in sub-zero temperatures in the Antarctic - but that will pale in comparison with the inaugural Genghis Khan Ice Marathon.

Shona and her running mates, expedition leader David Scott and runner Dr Andrew Murray, fly to Mongolia tomorrow for the race on January 27.

She said: "I'm trying not to overthink it. It's very easy for something like this to become all consuming but at the end of the day it is only an extremely cold run in Outer Mongolia.

"I'm sure when I get out there the adrenaline will start flowing but so far I've not had any sleepness nights.

"There are so many new variables for your body to cope with, from the jetlag to the food to staying in gers with local nomads to the bitter cold.

"It is impossible to predict what will happen on the day or how your body will react to the cold.

"In some ways, these types of challenge are less pressure than conventional marathons as it is very hard to target a time when you're running in minus 40 degrees Celsius on ice.

"For me, the main competition is the conditions: the risk of frostbite, hypothermia and the local wolves."

Shona, an investment banker, intends to use the challenge to raise money for two charities - SAMH and Riding for the Disabled.

Knowing her physical discomfort will raise funds for two causes close to her heart will help propel Shona to the finish line.

She added: "A huge part of my motivation for doing this is to raise awareness and funds for our two chosen charities, Riding for the Disabled and SAMH.

"Having a greater cause other than oneself is very important.

"It is always humbling to read stories about the challenges that many disabled people face and the incredible achievements so many gain through charities such as riding for the disabled.

"It puts a few cold runs into perspective."

Shona is also running the Tokyo marathon in late February so sees the Mongolia challenge as partly a training run for that.

But the training for the Mongolia ice race has been anything but easy.

She said: "My training never goes to plan.

"I've had a couple of health issues to manage along the way but I've done my best to keep going and not let them hold me back too much.

"The kit is the other big challenge but Ellis Brigham and Berghaus have been fabulous with their knowledge."

Mongolia is often considered one of the most savage places on earth and the Genghis Khan Ice Marathon will be one of the toughest runs the competitors will ever undertake.

Husky dogs will be on patrol to keep competitors save from wolves and will pull supply sleds.

Shona, who grew up in Craigmaddie, near Glasgow, added: "The great thing about this trip is that there are several aspects to the adventure.

"The marathon is just part. I'll also be riding a Mongolian horse to raise awareness of the benefits of riding for the disabled.

"David Scott, from Sandbaggers, who is organising the inaugural Genghis Khan ice marathon also has some plans lined up with the fifth Ulan Bator burns supper, as well as supporting local community initiatives.

"Lastly, and by no means least, Dr Andrew Murray is forging some great golfing links with Mongolia and is doing a solo 100km run as well."

To donate to RDA or SAMH see uk.virginmoneygiving.com/team/GhengisKhanIceMarathon or to sponsor Shona email ST@SlowTwitch.co.uk or David Scott david@sand-baggers.com