Acclimatisation is not mandatory for the North Pole Marathon. The race occurs at sea level so there are no altitude-related issues. The main challenges from a running perspective are the Cold and the Underfoot Terrain.
Cold: The correct clothing is an essential element in dealing with the cold. Please refer to the Race Gear section for information on clothing.
Underfoot Terrain: The underfoot terrain can be energy sapping in places, though the snow will not be deep except in patches. The aircraft landing runway may be incorporated into the race loop so there will be solid ice for at least one-fifth of the course.
Training in Freezers
Having some prior experience of running on ice / snow terrain in temperatures of -25C with your polar clothing would obviously be advantageous, but probably not practical for people who live in more temperate climates. As a result, some competitors have come up with innovative means of preparing for the race. These methodologies have ranged from running on beach sand to running on treadmills in freezers. The videos below from Spanish and French national television stations show athletes training in a giant industrial freezer.
Training in a Cold Weather Environment
There is probably no substitute for training in a cold weather environment and testing your gear in underfoot snow conditions. It is important to wear the full set of gear and practice temperature control in particular. A critical element is to never become too warm and sweat a lot - or too cold - so ventilation and maintaining a good core body temperature is important.