Colorado Trail FKT: One Ultrarunner’s Quest to Run 500 Miles

What does it take to set the fastest known time (FKT) on a 500 mile trail that extends across the state of Colorado through unforgiving high altitude terrain of equal parts beauty and harshness?
Ultrarunner, endurance coach, and 2022 World's Toughest Mudder champion, DJ Fox wanted to find out. 

  • After moving to Durango, Colorado in 2022, DJ found himself running almost daily on the southern terminus of the Colorado Trail (CT). 
  • He became inspired by, curious about, and even slightly obsessed with completing the whole trek on his own two feet.
  • And to do it all in less than 7 days, 13 hours, 16 minutes, and 15 seconds–the FKT held by professional ultrarunner, Michael Mcknight

So he planned the perfect route and organized a crew to go the distance. 
🏃‍♂️Here's what happened...

The Colorado Trail stretches about 500 miles from the southwestern mountain town of Durango to the northeastern part of Colorado’s bustling capital city, Denver.

About the Colorado Trail

The Colorado Trail journeys eastward from the southwestern mountain town of Durango to the north eastern part of Colorado’s bustling capital city, Denver.
📌According to

  • It usually requires backpackers 4-6 weeks to hike the entire route. 
  • Each year, it’s estimated that 500 people complete the trail on foot, bicycle, or horseback.

📈Elevation Gain

As one would expect, there are plenty of mountains to climb in Colorado, and the Colorado Trail takes users right up and over some of the highest of them. 

  • With roughly 90,000 feet (27,432 meters) of vertical gain and loss over the entire route, adding high altitude to the equation, it's no wonder hikers budget weeks of time to complete it. 
  • The trail’s high point is 13,271 feet above sea level and the entire trail averages above 10,000 feet.

📍There are four recognized variations for the Colorado Trail route: 

  • West to East via Collegiate East (FKT held by Michael Mcknight, and the one DJ set his sights on)
  • West to East via Collegiate West (an additional 80 miles of trail added to the original route that users describe as more scenic, but is also higher in elevation and more exposed)
  • East to West via Collegiate East
  • East to West via Collegiate West
DJ’s crew and pacers were largely inexperienced when it came to supporting a multi-day endeavor. Over the course of DJ’s Colorado Trail FKT attempt, they would learn what it takes to chase a speed record of this magnitude.

🗓️The Colorado Trail FKT Journey Begins...

With the dream realized, DJ started planning immediately.
If he was to successfully take the FKT, the logistics needed to be perfect:

  • Dates
  • Crew
  • Pacers
  • Crew access points
  • Fueling
  • Hydration

He left no stone unturned. But even with the closest attention to detail, DJ was well aware that planning would only take him so far. 
Five hundreds miles is a long way to run, and there are bound to be challenges along the way. 

🚎The Crew with Nick’s Van:🚐

🏃‍♂️The Pacers:🏃‍♀️

Crew members help DJ refuel between Durango to Molas Pass. He covered 75 miles on Day 1 of the Colorado Trail FKT attempt.

⛰️Colorado Trail FKT: Day 1

Durango to Molas Pass (75 Miles)

DJ launched from Durango on September 24th accompanied by his first pacer, Meredith Edwards.
Throughout that first day, DJ picked up pacers Will Mitchell and Miguel Medina who ran with DJ to Molas Pass– 75 miles from the starting point.
“The first day was perfect. Super relaxed,” says DJ.

  • He had anticipated the segment taking 21 hours, and he was spot on. 
  • He had initially planned a 4 hour nap at Molas, so following the plan, he forced himself to lay down for a couple of hours, but restful slumber eluded him. 

By the time the crew had him ready to leave Molas, DJ learned his first lesson from the trail: Wait for sleep to find you. 
“I didn’t sleep for the first 48 hours entirely,” says DJ.
“I would’ve been better off trying to move through it and sleep when needed.”

DJ's crew treats his foot between Molas to Spring Creek Pass during Day 2 of his Colorado Trail FKT attempt.

⛰️Colorado Trail FKT: Day 2

Molas to Spring Creek Pass (54.2 Miles)--129.2 Miles from start

“Day two went sideways immediately,” says DJ.
It was when he experienced the first major hitch in the plan. 

  • One of his key pacers that was supposed to be along for the rest of the journey decided to drop, leaving only two long-term pacers remaining–Sam Siddons and Nick Bailey. 
  • This meant that the two would have to shoulder the literal burden of the heavy pacer pack for the remaining 420 miles. 
  • Sam ran two exhausting back-to-back sections with DJ, totalling 40 miles, before Nick stepped in at Carson Saddle. 

👊Even amidst the jarring disruption to the original pacer plan, DJ had a chance to simultaneously celebrate and acknowledge the gargantuan trek he was embarking on.
“I had a really cool moment here, realizing that I had reached my personal record in regards to the furthest distance I had ever run before. 105 miles," says DJ.
"Every step here on out would be a new PR. But as is the nature of ultrarunning, the highs are high, and the lows are inevitable."
🦶A new obstacle presented itself later when DJ’s tibialis anterior flared with pain. 
“It hurt to pick my left foot up off the ground…I couldn’t rotate my ankle at all.” 

  • DJ tried to cross fiber the muscle for relief. 
  • It brought some, so he kept moving. 

🏃‍♂️At the time, DJ thought to himself:
"'I’ll at least hobble my way to the next section and we’ll figure it out from there.” 
Upon reaching Spring Creek, DJ was unable to move his left foot. 

On Day 3 of his Colorado Trail FKT attempt, DJ reached the high point on segment 22 (Spring Creek to Carson Saddle) at 13,271 feet.

⛰️Colorado Trail FKT: Day 3

Spring Creek to Hwy 114 (56.4 Miles)--185.6 miles from start

The next morning, DJ woke up still unable to move his left foot. 
The first doubtful thoughts crept in. With his emotions high, the crew came together:

  • They rubbed, poked, and prodded him in hopes of easing the discomfort. 
  • Eventually, they taped his foot up in a flexed position.
  • Then added a compression sleeve, and sent him on his way. 

So, DJ started playing some mind games with himself:
"'You can quit at the next stop’ is what I told myself. ‘Next’ never really arrives.”

The whole day was a bit of a grind...

...due to the ankle/foot issues and they moved much slower than planned. 

  • Unless DJ was climbing something steep and fully engaging his calf, he was in pain. 
  • The flat sections and descents, usually DJ’s strengths, took their toll.

With Nick and Sam pacing DJ for most of the day, they handed the baton to Will once nighttime fell.

  • DJ and Will made their way to Highway 114 where DJ planned to catch some sleep in the crew’s van. 
  • During those miles in the dark, DJ started to develop a cough–nothing too concerning, but notable.

⛰️Colorado Trail FKT: Day 4

Hwy 114 to US Hwy 50 (50.5 miles)-236.1 miles from start

After a few hours of sleep, DJ woke up with a nasty cough and some mucus starting to develop in his lungs and his ankle/foot were still quite painful.
With his pacer, Robyn Lesh, DJ made his way across a beautiful 20-mile section towards Sargent’s Mesa where Nick would take over pacing duties.
It was this day when things seemed to take a turn for the better, DJ recalls:
“I was aware that we were slowing down a bit due mostly to my ankle at this point, but Nick really got me motivated to try and pick up the pace regardless," says DJ.
"We started to push through the discomfort just a bit more and the pain actually started to fade away."
"I remember getting into an aid station and saying something along the lines of, ‘my body is starting to cooperate.’ My mind had no intention of quitting so maybe my foot finally got the message?”

  • With his foot/ankle finally cooperating, DJ was able to start jogging the flats on the last section of this day. 
  • With some rest at the end of the segment, he had high hopes for the following day.
Colorado Trail FKT: Day 5 from Highway 50 to Twin Lakes (51.3 miles)—287.4 miles from start.

⛰️Colorado Trail FKT: Day 5

Hwy 50 to Twin Lakes (51.3 miles)-287.4 miles from start

DJ woke again with phlegm and mucus filling his lungs. He spent the early parts of day 5 clearing everything out.

  • Two fresh pacers from Salida’s running store, 7000 Feet Running Company, joined the party. 
  • OCR athlete Dolan Potts ran with DJ for the next 33 miles before ultrarunner Justin Walker took the pacer pack for the following 30 miles. 

DJ remarked on how fresh his legs felt, yet how heavy his lungs were becoming.

  • He was finally able to move on the flats, but breathing heavily on any climb resulted in a disconcerting wheeze. 
  • “I was frustrated at the dichotomy I was experiencing within my own body, but happy to be picking up the pace from the previous two days.” 

On the final 11 mile section of day 5, as DJ and Sam trekked along, DJ experienced a coughing fit in the middle of the trail.
And there it was…blood. 
DJ discounted it as merely a bloody nose and kept moving. The FKT was still in sight. 

DJ logged multiple weeks of high mileage (100+ miles/week) training before embarking on his Colorado Trail FKT. Photo Credit: Chloe Rebaudo (@chloerebaudo). But would it be enough to cover all 500 miles?

⛰️Colorado Trail FKT: Day 6

Twin Lakes to Copper Mountain (65.8 miles)--353.2 miles from start

After another morning of clearing his lungs of phlegm, DJ got moving with Nick.
After a few miles, he started to feel a familiar sensation in his knee–ITBS (IT band syndrome).
Luckily, they were able to give the crew an update on DJ’s IT band issue before meeting at the next planned junction.
This was the point at which DJ noticed a change in his crew, as they had assembled a pit stop worthy of Formula 1..
After 300 miles and more than 5 days on the trail, they were a well-oiled machine.
DJ explains the scene: 

  • “Will and Sam immediately get to work with their hands, attempting to find the right muscle release through massage."
  • "Someone is doing the same with the percussion gun."
  • "Eric is spoon feeding me."
  • "Someone is putting sunscreen on my face." 
  • "People are filling up my pack and bottles.” 

After the crew finished with DJ...

  • Another OCR athlete, Shane Terry picked up pacing duties for the next 26 miles. 
  • Marshall Thompson then hopped in at Timberline Lakes Trailhead, pacing DJ to Copper Mountain.

“Marshall paced it perfectly," says DJ.
"I just got behind him, clung to his heels, and got to the top of the pass where it was extremely cold and windy."
"After a quick and flowy descent (again, my legs felt great. It was hard for me to believe how well I could still run at this point), I realized that I was wet from sweating. This became an obvious mistake very fast as I started to get cold quickly.”
Luckily, the crew wasn’t too far away...

  • Once in the warm van, DJ tried to sleep, but frustratingly woke several times to involuntary coughing fits;.
  • "It’s a major bummer when you can’t sleep but know how badly you need it,” he says.

⛰️Colorado Trail FKT: Day 7

Copper Mountain to Long Gulch (60.4 miles)-413.6 miles from start

As DJ prepared for the home stretch of this FKT, he cleared his lungs using steam, but this time everything was tinted red with blood.
Nervous, yet determined to continue chasing the record, DJ departed Copper Mountain with Sam and Shane.

On the first climb of the day, DJ couldn’t catch his breath.
“It started to affect me mentally…during the downhill I had my first real low of the effort. First real low during an event of my athletic career so far actually,” says DJ.
He felt terrible.
Asking for the pulse oximeter, DJ checked his metrics...

  • 67% oxygen saturation–that had to be an error. 
  • Sam checked his own as a reference. It read 78%, so they assumed the oximeter was malfunctioning. 
  • After sitting for a moment, DJ rechecked and his saturation was back into the 80s–low, but acceptable. 
  • They kept moving and met the crew at the next checkpoint. 

The crew rallied DJ’s spirits and turned him loose with pacers, Sam and Nick.

  • They sandwiched DJ between them to help push and pull him through the next section of trail. 
  • DJ’s only job was to put one foot in front of the other. 

After another quick pit stop John Crawford, Nick, and Shane hiked with DJ for the next section. 
“This one was an absolute grind,” says DJ. 
“I was really starting to break down now. I could only keep a good hiking pace for short periods of time before I started to lose my breath and was forced into a much slower walk."
"I tried every mind trick in the book to convince myself that I could keep pushing. It got me to the next aid stop.” 

Although it wasn’t an easy decision to make, DJ opted in favor of his long-term health and ended the FKT attempt with roughly 60 miles to go.

⛰️Colorado Trail FKT: Day 7 + An Impossible Decision

The crew met DJ at Kenosha Pass. Will picked up pacing duties, but as they pushed forward...
DJ realized that pushing his body to keep up with record pace was starting to feel dangerous.
Every inhale was accompanied by a wheeze, and with every exhale, an unnerving rumble.

  • “To say I was frustrated here would be an understatement."
  • "I was broken…just over 60 miles from the finish of my 485 mile journey and I was falling apart."
  • "My body felt great, my spirit was strong, but my lungs were failing me.” 

Still on pace for the FKT, DJ had to make an impossible decision...

  • 👍Keep pushing for the record and jeopardize his long term health, OR...
  • 👎Call it 60 miles from the finish and preserve his body for future efforts.

As DJ sat waiting for his ride to the hospital, he cried, shivering from the cold.
His pacer, Will, layered DJ up in everything they had available trying to keep DJ warm until the ambulance arrived.
Sitting, finally giving his body the permission to stop after refusing its demands for so long, DJ felt his lungs filling with fluid, and fast.
Once he arrived at the hospital...

  • They diagnosed DJ with pneumonia and found a heart arrhythmia that had his resting pulse leaping erratically from 70 bpm to 190 bpm instantaneously.  
  • The EKG tests weren’t pretty either. 
  • After holding him for 40 hours, the hospital released DJ, finally allowing him to return home to Durango. 
Undeterred by this unexpected ending to his Colorado Trail FKT journey, DJ doesn’t feel like he’s walking away empty-handed or thwarted from trying again.

“At the end of the day I'm grateful for everything," says DJ.
"I'm grateful for everyone who helped me along the way, especially the crew and pacers who started with me in Durango and took an entire week of their lives to help me chase my dreams. I'm grateful for...

  • Everyone who jumped in along the way to pace and crew, even if only for a single section.
  • A mind and body that is willing to try hard things.
  • The difficulties that I faced while racing the CT.
  • And grateful for how amazing the whole experience really was. It is something that I will remember and cherish for the rest of my days."

DJ plans to reattempt the Colorado Trail FKT in 2024.
He knows that this year’s experience taught himself and the crew many valuable lessons that will translate to a fresh and faster Colorado Trail FKT attempt. 
“I think we can really do something special out on that trail…hopefully next time I just don’t get sick!”

⛰️Colorado Trail FKT: The Reflection

Q: What were some key takeaways you had from this experience that you’ll take into next year’s FKT?

 DJ: There are modifications I need to make in my training that will help me handle the demands of the trail better. 

  • Specifically, I need to hike more flat and extremely low grades. I believe that will prevent the ankle issues that I experienced. 
  • I also think that prioritizing solid food earlier on will prevent some of the damage that I did to my mouth, if they weren't entirely related to getting ill.

Q: What pacing/crew strategies really helped you along the way?

DJ: Justin and Dolan had tons of pacing and crewing experience. They pace runners at the Leadville 100 every year. 
Justin was the first person who was able to pace me from the front. 

  • Up until that point, it was me having to run from the front. This brought me back to the world of a mix of ultra shuffle/walking, which was a really good way to switch up muscle groups. 

Dolan helped the crew organize the pacer bag and prioritize what needed to be in the bag, making it much lighter. 

  • They were able to anticipate my needs and not bring anything extra. 
  • At crew points, there was no more asking ‘what do you need?’ Each person had a role. This made pit stops more efficient. 

Q: What aspects of your training paid off the most for this FKT attempt?

DJ: Spending so much time at altitude (10,000'+) was a major success. 

  • I seemed to handle the altitude of the trail very well. 
  • I didn't necessarily get altitude sickness that bothered my respiratory system, I got pneumonia. 
  • The training that went on at these high altitudes was also of high value. 
  • It was a ton of steep hiking and downhill done at an extremely easy effort. 
  • The plan was just lots of time on feet, and I think it went as well as it could have for the 14 weeks I trained specifically for this.

Q: What gear really pulled through for you on this adventure?

DJ: My shoes were honestly perfect for this. 

  • I wore Speedland SL:HSV for the first 75 miles and a single pair of Speedland GS:TAM for the next 345 miles. 
  • The shoes are still in excellent shape and my feet stayed relatively healthy. 
  • Some beat up toes, but only a single blister on my heel.
DJ takes a quick break on the side of the trail with his legs up. The GS:TAM was the perfect shoe for the last 345 miles of the journey. Photo credit: Nick Bailey.

Q: What was your favorite section of the trail and why?

DJ: It's hard to beat the beginning section going through the San Juans. 

  • Most of it is above 12,000' and wide open. 
  • You can see forever, and it's just incredibly beautiful. Nothing words can really do justice for. 
  • The foliage was nearly perfect the entire time, so every part of the trail had a special shine to it.

Q: How do you mentally train/prepare yourself to deal with adversity in ultramarathons and multi-day events?

DJ: I think that most of it comes from the daily commitment to the singular goal. 

  • You get up every single day with the intention of preparing for whatever event you chose and put in time and energy towards it. 
  • If you really care about it and put the work in, you'll always look for a way to continue when things inevitably go wrong. 
  • I'm learning that you prepare the best you can, but will have things to deal with on the fly no matter what. 
  • Think of what situations you could encounter along the way ahead of time, and then think of how you could remedy the situation.
  • Nothing will prepare you like experience will though. You have to get out there and learn on the job.

Q: What is your strategy for dealing with the inevitable “failures” that arise from dreaming big in the sport of running?

DJ: I don't know if I really have a specific strategy to deal with failure. I just know it's going to come around and I'm not afraid of it. 

  • I may have failed at hitting the target I put out in front of myself, but I didn't truly fail. 
  • The goal is something to aim for, but what we do on our way there is the true trophy. 

Choosing this as my event left me vulnerable, but it also helped me grow as an athlete more than anything I've done so far. 

  • I succeeded in the training. I succeeded in the commitment. 
  • I succeeded in the effort put forth. 
  • I succeeded through the experience I've gained. 

There are more wins than losses within our failures if we really evaluate the situation. 
I have failed over and over again in this sport, but I still believe that I can do incredible things if I dedicate myself to it. 
My failures have pushed me further and harder than any success I have ever experienced. 

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Abigail Lock
Durango, CO
24 Following

Endurance athlete with a proclivity for mountain running and high altitude desert dwelling. NASM Certified Sports Nutriti...


Bill Lock Enlightening, I'm new to 'extreme' sports, but extremely impressed! Great article, I felt like a part of the team, I was rooting for you all the way! Can't wait to hear about your next attempt!

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