OSJ KOUMI100 takes place on Sun, Oct 11, 2026 in Koumi, Japan. The main route is 165 km.
- Date
- Sun, Oct 11, 2026
- Start
- Koumi 🇯🇵
- Distance
- 165 km
- Climbing
- 7,500 m
- Level
- Open to all
Toe the line at OSJ KOUMI100 in your best shape
A training plan built around your fitness and this race, adapted every day as your form changes. Attach the course and it prepares for the climbs too.
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OSJ KOUMI100 is a grueling 100-mile trail race held in Koumi, Nagano Prefecture, consisting of five 33km loops around Matsubarako Lake and Inago-yu.
What this race demands
OSJ KOUMI100 demands absolute metabolic resilience and immense structural durability to complete five grueling 33km trail loops totaling 100 miles.
Ultra-Distance Endurance
Covering a 100-mile distance requires sustained cardiovascular output and extreme muscular endurance over many hours of continuous movement.
Loop-Based Pacing
The five 33km loop structure around Matsubarako Lake and Inago-yu demands strict pacing discipline to prevent early fatigue on repetitive terrain.
Structural Durability
Sustaining locomotion across multiple trail loops tests joint and connective tissue resilience against repetitive impact.
To sustain energy across a 100-mile trail race lasting well beyond standard endurance limits, athletes should target 60 to 90 grams of carbohydrates per hour.
Frequently asked questions
When is OSJ KOUMI100?
OSJ KOUMI100 takes place on Sun, Oct 11, 2026 in Koumi, Japan.
How long is OSJ KOUMI100?
The main route is 165 km.
What does OSJ KOUMI100 demand?
OSJ KOUMI100 demands absolute metabolic resilience and immense structural durability to complete five grueling 33km trail loops totaling 100 miles.
How much climbing does OSJ KOUMI100 have?
OSJ KOUMI100 has 7,500 m of climbing.
Who is OSJ KOUMI100 for?
OSJ KOUMI100 is open to all participants.
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