A business consultant from Glasgow became the first Scot to complete all three polar marathons, when she finished the UVU North Pole Marathon in seven hours, 13 minutes.

Audrey McIntosh said she endured the toughest race of her life, in the most brutal weather conditions and course. in the event's 13-year history. Temperatures plunged to -41C while armed marksmen were on hand to protect competitors from polar bears.

The 51-year-old mother-of-two was just 16 minutes behind the first woman to cross the line on Saturday and was fourth female in a field of 44 international competitors.

Named the World's Coolest Marathon, the race is staged near the Geographical North Pole on the Svalbard archipelago. The course took in 12 x 3.5km laps on ice floes six to12 feet thick, in ankle-deep snow and 10mph winds.

Compared to her previous Antarctic marathons in 2013, McIntosh says: "The cold at the North Pole was more biting and I have some minor injuries as a result, with wind nip, frost nip and second degree frostbite on my ears.

"With the wind and cold, the sheer physical effort was harder and tougher mentally, but I was determined to finish. It's the greatest sense of achievement."

Audrey used a blackcurrant dietary supplement, to aid blood circulation, oxygenation and recovery for the extreme event.

McIntosh's Arctic race will form part of scientific research into the impact of extreme exertion in debilitating cold by Nairn Scotie of Glasgow University's School of Life Sciences.

Having achieved all three polar marathons, McIntosh is now setting her sights to run seven 50km endurance events on seven continents in seven days.

McIntosh's polar Odyssey was run in aid of Alzheimer Scotland. To date she has raised almost £16,000 for the charity and is seeking to beat her target of £20,000.

She is now due to compete in Glasgow's 53-mile Ultra Marathon; The Hoka Highland Fling through Loch Lomond & Trossachs National Park to the village of Tyndrum, in just two weeks; followed by a 95-miler in June and 42-mile race on the Devil of the Highlands in August (the West Highland Way triple crown), and the Glenmore 24 (hour) trail race near Aviemore in September where she hopes to complete 100 miles.