SNOW, ice and temperatures plummeting to -30C aren't ideal conditions to run a marathon, but the challenge Audrey McIntosh has set her sights on is no ordinary endurance run.

Instead of pounding pavements she will test her fitness to the limits on a stretch of groomed snow that covers crevasses on an active glacier in Antarctica.

The 50-year-old freelance IT project manager, from Cathcart, will be the first Scot to compete in the Antarctic Ice Marathon later this month: a 42.2-kilometre marathon followed by a 100k ultra race with one rest day in between.

"I think it's going to be gruelling," admits Audrey.

"I've been told it will take one-and-a-half times the effort of running a normal marathon under normal conditions.

"The marathon will probably take me six hours and I think the ultra marathon will be 18 or 19 hours. The schedule has a day off but last year they ran on consecutive days because of the weather so I have to be prepared to do that."

Intensive training started a year ago and Audrey has dropped from a size 14 to a 10, running up to 30 miles four times a week.

She has included key events and marathons, including the Glen Ogle 33 ultra marathon, in her training regime as milestones to judge fitness along the way.

"To prepare for the conditions I've actually done a lot of running on sand because that simulates the snowy surface, which is much harder to run on.

"In terms of preparing for the cold, other than running in our own winters as much as I could when temperatures dropped, I haven't been able to do anything else," she says.

"It's a different type of snow to ours, it's drier, harder and more icy. "Everyone says firm, wet sand is probably the equivalent so I've been doing a lot of beach running."

If the thought of running a marathon and ultra marathon isn't enough to put most people off, the journey itself will take two days to travel to Punta Arenas in Chile, then on to Antarctica, 600 miles from the South Pole in the Chilean sector.

Audrey will sleep in a tent, with outside temperatures reaching as low as -40C overnight in the southern hemisphere's summer, when the sun doesn't set.

"I have been working with a nutritionist and sports scientist at the University of Glasgow, it hit home how massive a challenge this is going to be when they talked to me about how tough it would be on my body," she says.

THE professionals said my head will keep me going, I will suffer from low blood flow to my extremities and my core temperature will be erratic.

"I will experience a lot of pain and swelling, but I need to keep positive to get through it."

If being surrounded by the continent's overwhelming landscapes aren't enough to keep Audrey going, she is asking well-wishers to send motivational tweets to spur her on in the event to raise funds for Alzheimer Scotland.

She will print them out before she goes, then put them in her drop bags with food and drink to be picked up at eight stations along the way of the race.

"That will give me encouragement and I'll remember people at home are thinking about me," she adds.

Now in its ninth year, only 28 Britons have completed the race, with only nine British women completing the marathon and two the 100k. Only one other British woman has completed both distances together.

So far Audrey, whose uncle suffers from dementia, has raised more than £5000 for Alzheimer Scotland. But she expects more money to come in after the event.

She has paid the registration fee herself, with the help of sponsors Askharad Consulting, which means all the money raised goes to charity.

"That's really important to me: the charity gets all the money I raise in their name," she says.

"I've never taken charity places in races because I know a lot of the money goes to pay off admin costs."

Her husband Alasdair and two daughters, who have been helping to raise funds, will be waiting at home to hear how she fares in the challenge.

It is a long way from the first 10k she ran in 1998 to raise £500 for Glasgow's Victoria Infirmary after Alasdair was treated for non-Hodgkin's lymphoma.

SHE said: "Charity has always been a big thing for me and for the family.

"I think it's important that you give back into society to help those less fortunate.

"I feel quite nervous but there's a bit of me that's feeling quite confident in my training and my preparation.

"I know I'm strong and I'm fit and have the distance but the big unknown is the conditions. It goes without saying, my family think I'm slightly mad to be doing this."

You can tweet or Facebook Audrey a message @AudreyMcIntosh.

To donate, visit McIntosh1 or text 70070 with the code ICEM50 + amount (£1, £2,£3,£4, £5, £10).