Last updated: December 19, 2025
Definition of Endurance Trail Running
Endurance trail running is a long-distance running discipline that takes place in natural environments, such as mountains, forests, and deserts. It is characterized by the following elements:
Distance:
Starts at 100 km and includes ultra distances that can exceed 200 miles.
Courses typically require sustained physical effort over extended periods, ranging from several hours to multiple days.
Terrain:
Involves varied natural terrains, such as rocky paths, single tracks, dirt roads, and steep ascents/descents.
A significant percentage of the course is mountain trails, forests, deserts, or other challenging environments.
Elevation Gain and Loss:
Defined by substantial vertical climbs and descents, contributing to the technical and physical challenge of the course.
Self-Sufficiency:
Athletes are required to carry essential gear (e.g., hydration packs, nutrition, emergency supplies) to navigate remote and often extreme conditions.
Community and Sustainability:
Emphasizes camaraderie among athletes and respect for the environment, often adhering to "Leave No Trace" principles.
Objective:
The primary goal of endurance trail running is to test physical and mental limits, immerse in nature, and showcase the beauty of unique landscapes while fostering a sense of achievement.
Course Rules
Definition of an Endurance Mountain Trail Race
An endurance mountain trail race is a competition held in natural environments, including mountains, deserts, and forests. The course must:
Be open to everyone willing to participate.
Range in length from 100 km to 200 miles or more.
Include at least 30% mountain trail sections and up to 70% variations (e.g., asphalt, sand, snow, dirt roads).
Feature naturally variable terrain with substantial ascents and descents, resulting in significant elevation gain and loss.
Course Guidelines for the One Hundred® World Championship
100 km Races
Distance: 90–110 km (plus an additional 5% margin of error to accommodate for GPS variance is accepted).
Vertical Climb: At least 2,000m and no more than 8,000m of elevation gain.
Terrain:
At least 30% mountain trails.
The remaining 70% can include asphalt, sand, snow, or dirt roads.
Competitions Within the Race:
King of the Summit Competition:
Segment with 1,000m vertical ascent over 8–12 km.
Elevation gain and loss may vary by up to 20%.
Mountain Goat Competition:
Segment with 1,000m vertical descent over 8–12 km.
Elevation loss and gain may vary by up to 20%.
100 Mile Races
Distance: 95–105 miles (plus an additional 5% margin of error to accommodate for GPS variance is accepted).
Vertical Climb: At least 3,000m and no more than 12,000m of elevation gain.
Terrain:
At least 30% mountain trails.
The remaining 70% can include asphalt, sand, snow, or dirt roads.
Competitions Within the Race:
King of the Summit Competition:
Segment with 1,000m vertical ascent over 8–12 km.
Elevation gain and loss may vary by up to 20%.
Mountain Goat Competition:
Segment with 1,000m vertical descent over 8–12 km.
Elevation loss and gain may vary by up to 20%.
200 Mile Races
Distance: 190–200 miles (plus an additional 5% margin of error to accommodate for GPS variance is accepted).
Vertical Climb: At least 5,000m and no more than 40,000m of elevation gain.
Terrain:
At least 30% mountain trails.
The remaining 70% can include asphalt, sand, snow, or dirt roads.
Competitions Within the Race:
King of the Summit Competition:
Segment with 1,000m vertical ascent over 8–12 km.
Elevation gain and loss may vary by up to 20%.
Mountain Goat Competition:
Segment with 1,000m vertical descent over 8–12 km.
Elevation loss and gain may vary by up to 20%.
Safety and Environmental Standards
Safety Protocols
Mandatory Medical Checkpoints: Required for races exceeding 100 km to ensure athlete well-being.
Athlete Self-Sufficiency: Runners must carry essential gear for extreme conditions (e.g., hydration packs, emergency blankets).
Environmental Responsibility
Waste Management Plans: Organizers must implement systems to reduce waste at aid stations.
Sustainability: Courses must adhere to Leave No Trace principles and use biodegradable markings wherever possible.
Restricted Motorized Access: Motorized vehicles are prohibited on trails except for emergency response.
