40/50 Mile Challenge - Lake Carl Blackwell (May 23, 2026)
Course Description:
Lake Carl Blackwell, Stillwater, OK
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The course at Lake Carl Blackwell features a scenic and runnable trail system that loops through rolling lakeside terrain, open grasslands, and wooded sections. Runners will complete a clearly marked 3.1-mile (5K) loop, returning each lap to the same central start/finish area and fully stocked aid station.
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The trail surface is a mix of dirt paths, grass, and lightly packed earth, with gentle rolling elevation that adds interest without becoming overly technical. The course offers good footing and wide sections, making it approachable for newer trail runners while still engaging for experienced endurance athletes over multiple loops.
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With expansive views of the lake and surrounding landscape, the loop-based format allows runners to pace themselves, refuel easily, and decide how far they want to go—whether that’s one loop or an extended endurance effort. The combination of natural beauty, manageable terrain, and centralized support makes Lake Carl Blackwell an excellent venue for athletes of all experience levels.
Support & Logistics
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Runners may access personal supplies at their staging area each loop
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Crew access permitted in designated areas
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Pacers allowed per event rules (location-specific and time-based)
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Medical and race staff on site throughout the event
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This setup allows runners to adapt strategy on the fly—fueling, gear changes, and rest without leaving the course.
Running Alongside The Next Loop, The 40/50 Mile Challenge runs simultaneously with The Next Loop Endurance Series on the same course.
While Next Loop participants run on the hour, 40/50 Mile Challenge runners race continuously and are scored separately.
Each event has its own competitive field, results, and rules.This creates an energetic race environment while preserving the integrity of both formats.
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Ready to Take on the Challenge?
Registration is limited to ensure course quality and runner support.
Location: Lake Carl Blackwell
11000 W Hwy 51, Stillwater, OK 74074
Distances Offered: 40 Mile, 50 Mile
The 40/50 Mile Challenge
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The 40/50 Mile Challenge is a continuous loop endurance race designed for runners who want to push beyond traditional race formats while benefiting from a fully supported, centralized course.
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Held alongside The Next Loop Endurance Series, this event runs on the same 3.1-mile (5K) loop, but unlike the hourly format, competitors in the 40/50 Mile Challenge run continuously with a strict time cutoff.
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This format offers a true ultra-distance experience—simplified logistics, consistent footing, and constant access to aid and support.
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Event Format
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Distances: 40 Miles or 50 Miles
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Loop Length: 3.1 miles (5K)
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Course Type: Continuous loop trail race
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Time Limit: 12 hours
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Start/Finish: Same location each loop
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Aid Station: Fully stocked at every lap
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Staging Area: Designated personal staging area near start/finish
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Runners complete repeated loops until they reach their chosen distance or the time limit expires.
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Who Should Run the 40/50 Mile Challenge
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This event is ideal for:
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Runners attempting their first ultra distance
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Athletes stepping up from a marathon or 50K
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Experienced ultrarunners seeking a fast, efficient course
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Competitors who value logistics simplicity and strong support
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The loop format removes navigation concerns and allows athletes to focus entirely on pacing, fueling, and mental toughness.
