The Rules

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:

1. 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.

2. 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.

3. Elevation Gain and Loss:

   • Defined by substantial vertical climbs and descents, contributing to the technical and physical challenge of the course.

4. Self-Sufficiency:

   • Athletes are required to carry essential gear (e.g., hydration packs, nutrition, emergency supplies) to navigate remote and often extreme conditions.

5. Community and Sustainability:

   • Emphasizes camaraderie among athletes and respect for the environment, often adhering to "Leave No Trace" principles.

6. 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:

1. Be open to everyone willing to participate.

2. Range in length from 100 km to 200 miles or more.

3. Include at least 30% mountain trail sections and up to 70% variations (e.g., asphalt, sand, snow, dirt roads).

4. 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

1. Mandatory Medical Checkpoints: Required for races exceeding 100 km to ensure athlete well-being.

2. Athlete Self-Sufficiency: Runners must carry essential gear for extreme conditions (e.g., hydration packs, emergency blankets).

Environmental Responsibility

1. Waste Management Plans: Organizers must implement systems to reduce waste at aid stations.

2. Sustainability: Courses must adhere to Leave No Trace principles and use biodegradable markings wherever possible.

3. Restricted Motorized Access: Motorized vehicles are prohibited on trails except for emergency response.