Based on current Italian Law for participation at sport events (D.M. 18.02.1982 tab. B) UTLM races are open to everyone who is 18 years old on September 18th 2021, holding a valid agonistic sport medical certificate (template on www.UTLM.it). For 81K race, we advise participants to have completed at least one TRAIL race on mountain terrain of about 50 Km and 2.500m D+. Every participant must be aware of chosen race length and specific terrain where the race takes place, be well trained and have gained, before the race, a full capacity of self-autonomy in a mountain environment, in particular: - Be able to eventually face weather conditions, which could become difficult. Alpine environment conditions can change fast and drastically, so this is an aspect that cannot be underestimated; therefore, participants must be able to face extreme weather conditions as intense cold/hot, snow or rain, strong wind etc. - Be able to manage eventual physical/psychological problems connected to high level of tiredness, stomach problems, muscular/articular pain, small wounds, starvation/dehydration feelings etc. - Be conscious that the OC role is not helping or assisting the participant to complete the race.