Background The Genghis Khan Ice Marathon took place in January 2016 in the mountains of the Terelj National Park, Mongolia at an altitude of 1800 metre. The route was a 26 mile marathon following the route of the frozen Tul Goll River. Conditions on race day were dry, sunny, light wind, with an air temperature of minus 35°C.

Aim To assess the effect of competing in a marathon in an extreme cold environment in a group of experienced ultrarunners.

Method A multinational group of experienced ultrarunners (n = 9, male 5, female 4, age range 25-53 years) completed a post race questionnaire detailing any adverse effects encountered when competing in the marathon. All athletes also rated the perceived effort of the race on the Borg Scale. Two weeks after the event all runners were contacted via email to determine if any illness or injury had occurred in the post race period.

Results The race was completed in 3:05 – 5:50. One person did not finish the race due to a navigational error. All athletes completed the post race questionnaire and the two week follow up email survey. No significant difficulties were encountered during the race. The cold air caused freezing around the nostrils and irritated the airways but no one experienced any cold induced bronchopasm. Clothing froze due to sweat and expired air but there were no cases of hypothermia. There were two cases of frostbite; earlobe (moderate) and nose (mild). Borg scale of perceived exertion values ranged from 13 – 17 (mean 15). On two week follow up all athletes had been well with only two cases of viral URTI’s reported. No athlete reported any DOMS in the immediate post race period.

Conclusion All the athletes were very experienced in ultrarunning having competed in mountain, desert or cold environments. This experience level possibly contributed to the lack of complications during the race and in the post race period. No athletes experienced any DOMS in the post race period which is unusual for this distance and presumably related to lack of peripheral muscular perfusion during exercise in extreme cold.