The warning is stark and unequivocal. "Situations which under normal circumstances don't cause any problems can become absolutely life threatening in the dead of winter in the Yukon. Please keep this in mind at all times."
Welcome to the Yukon Artic Ultra, supposedly the world's toughest race. It has a strong case to make, taking in 320 miles across a snow-blanketed, frozen wilderness with competitors having to carry all they need to survive. Included among the information packs for those wanting to take part is a graph, across it spreads a thin blue line tracing the maximum mean temperature for the time of year in Canada's northwestern corner. It sneaks up to -10. Beneath it a red line details the minimum mean and flirts with -50. Add wind chill and that takes it well into the red.
"There's some crazy people who do it," says Lewis Moody, a man who during his rugby career was given the nickname Mad Dog. "I absolutely loved it.
"It was so cold that the face masks you have to cover your nose and mouth were freezing solid around your face, your hood on your jacket froze, there was ice on your hair, ice on your eyelashes. It was an awesome experience."
For retired sports men and women the question of what to do next, how to replace the high of competition, is often a quest in itself. For Moody, a former England captain and World Cup winner, an answer was to be found in the Yukon even if it was not to be answered satisfactorily, at least not yet.
The challenge was to complete the 320 miles in eight days but Moody and his team, the polar explorer Alan Chambers and Phil Wall, who runs the HopeHIV charity the trio are raising money for, were forced to pull out after three days. Moody contracted frostbite in one of his fingers – one that had been damaged in childhood and the severed nerve meant he did not realise its onset until too late. Under the strict rules of the event that meant the end of the road and unfinished business. "We will be back next year," he insists.
"It was an incredibly brutal, tough race," continues Moody. "It did make me realise the challenge is what I love. I am bitterly annoyed that I had to pull out. Not being able to hit that goal – finish the race and raise that money – really plays havoc in the back of my mind. It's like a headache you can't get rid of and I need to go back and finish what I started.
"You want to fulfil the goals you set yourself and as a rugby player I've always been able to do it. For something like this to happen, because of a blister on the end of my finger – which is what it feels like – is even more frustrating. I was just fortunate I had Alan there to help me make the right call because otherwise I could be sat here now missing one finger."
The race begins in Whitehorse, the Yukon's largest town, and heads out along the Yukon River – which winds its way on to Alaska and some 2,000 miles later into the Bering Sea – before clambering into the hills and forests that channel the river's path. Day one threw up an unexpected challenge – it was not cold enough. Temperatures leapt to an unseasonal -5.
"That caused havoc for the race because it meant the snow became softer and much harder to run on," explains Moody. "It becomes like sand. A lot of people dropped out that first day because it was such hard going, a lot were being sick."
Around midnight Moody and his team-mates stopped to set up camp after 14 hours of trekking, tugging sleds weighed down with tents, sleeping bags, a stove, food, first-aid kit, and special down jackets in case the thermometer plunged towards the red line. Five hours later they were back on their feet, dawn breaking to reveal a cloudless sky as they headed for Dog Grave Lake.
"It's beautiful, some of the scenery is absolutely breathtaking," says Moody, "especially as the sun is rising or setting across the frozen landscapes. When you get to the top of the hills and look back there is this wilderness of woodland and mountains."
Chambers knew what a clear sky meant. As the day progressed, and they made good progress, well ahead of schedule, the temperature began to drop. As darkness fell Moody watched the frost creep across their sleds. At 8pm they reached a check point and huddled around a fire with other competitors, swapping tales, sipping hot water. It was -15. When they woke at 1am to resume the race, the inside of Moody's tent was layered in frost. It was -35. "When you unzip your sleeping bag and you have to get out that's when the cold really hits you."
It was while packing their gear that the frostbite took hold after Moody's silk undergloves got wet. But, as they set off into the darkness, he was unaware of the problem. Other thoughts were occupying his mind. "It's three in the morning and you find yourself starting to hallucinate. The trees were so tall and so frost covered, there is barely any natural light so everything takes a different shape and you are stumbling around because you are so sleep deprived. You are forcing yourself to keep your eyes open. And I swore I was walking down a New York street with all the shops and high rise buildings around me.
"One of the other guys told me he saw a stick and started having a conversation with it. People see all sorts of things – the last time Alan did the race he swore he was being chased by a panther. It turned out it was marks in the snow where pine combs had fallen from the trees but it didn't stop him running. It is very strange.
"You put one foot in front of the other and just keep going. When it gets to -35 you realise how isolated you are in that part of northern Canada. There is a real sudden realisation of the fact that if something did go wrong, like you broke your leg or anything like that then it was going to be quite a dangerous situation."
As he walked into the night the frostbite spread over his finger. "I took my glove off and saw the end of my finger was a bit white. When I touched it it was rock hard. I spent the next six hours rewarming it, hot pads, swinging my arms around, hoping it was frostnip – the onset of frostbite that if you catch at that stage is reversible. It was a painful process – all the cells in whatever part of your body it is turn to ice and you have to thaw them out, get the blood flowing again. I thought I'd got it back to normal, it felt good so I took my glove off. Alan said straightaway 'That's frostbite.' I was gutted, absolutely gutted. I had sat in the briefings and knew the rules. I knew my race was over."
Moody, Chambers and Wall aim to raise £300,000 for the young people in Africa supported by HOPEHIV. For more information see www.mygreatestchallenge.org, to donate go to www.justgiving.com/teams/mygreatestchallenge