On The Factory Floor at Arc Project 4: Inside the 24-Hour Indoor Treadmill Relay Race

"Time disappeared."

For Alec, a member of Salty Boys Athletic Club, winners of Arc Project 4, that sentence captures the experience perfectly. Twenty-four hours inside the 'The Treadmill Factory' had a way of doing that.

The Salty Boys motto is "Do mental s***" – and at AP4, that's exactly what they did.

Arc Project 4 was a 24-hour, indoor treadmill relay race, an endurance event where 50 teams competed on manual, unmotorized treadmills inside a warehouse transformed by light, sound and projection. One huge screen, shifting light shows and continuous DJ sets reshaped the atmosphere throughout the race, creating an experience that felt as much psychological as physical.

At times the space would disappear into complete darkness. The next, it would erupt into a blinding whiteout. For 24 hours, runners were immersed in an environment designed to distort their sense of time, effort and place.

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Inside 'The Treadmill Factory'

Inside Arc Project 4 – affectionately dubbed 'The Treadmill Factory' – the outside world quickly fell away. There were no left turns, no rain and no hills. Just relentless manual Woodway treadmills, music, light and effort.

Rob, the team's captain, summed up the difference:

"Outside, you've got wind, changing conditions, shade, that sort of stuff. Whereas here, mate, there’s no escape, no distraction. It's so hard."

The Salty Boys team was made up of sub-three marathoners, track athletes and ultra-runners, but despite their experience, nothing could have prepared them for the challenge ahead. What surprised them wasn’t just the physical demand, but the mental load of running hard, from nowhere to nowhere, never actually moving through space.

Their original plan of running long, sustained stints quickly disappeared under the physical and mental tax of the environment.

"It became military. We were methodical. We became so process-driven. We had no choice."

The team adapted, switching to relentless, rapid-fire 3-minute rotations – 3 minutes on, 3 minutes off – repeated for 45-minute blocks at a time.

During their precious 45-minute recovery windows, runners stepped off the treadmills and immediately collapsed in front of the huge industrial fans to cool down before taking on fuel and preparing to go again.

When Time Stops Making Sense

But regardless of their change of plan and recovery strategy, every runner hit a wall where the reality of the factory floor caught up with them.

For Katie, an experienced ultra-runner, the halfway point brought genuine doubt.

"I've always just been like, 'Well, I'm gonna get through it one way or another,' but with this one I actually wasn't sure if I could physically finish it," she said. "12 hours to go is still a really long time when you are really struggling."

Unlike a trail ultra where effort is constantly reshaped by the terrain, there were no descents to offer release, change of surface or gradient to naturally break your rhythm. At AP4 the effort never really changed, no moments of relief, and the familiar sense of movement and momentum disappeared.

"I found it hard to distinguish if I was in Berghain or running a marathon, or somehow both."

As the race wore on, time itself became increasingly difficult to grasp. Much like a night in the infamous Berlin nightclub Berghain.

"Because you were in a warehouse and it was pitch black, you had no concept of what time it was... I'd look at my watch and then I'd be like, 'Oh my goodness, it's 4pm.' The next time I'd look, I'd be like, 'Oh my goodness, it's 2am.'"

The immersive environment seemed to create moments of both intense focus and complete disorientation. At times runners became acutely aware of every sensation in their bodies. At others, hours appeared to disappear entirely.

A Dominant Victory For Salty Boys Athletic Club

By the end, the Salty Boys had built a dominant lead of more than 16 kilometres.

The victory was impressive, but what stood out even more was how the race exposed every competitor to the same psychological challenge. The team refused to chill and ran straight through the night without sleeping. They powered on at full gas while watching other teams walk and crumble around them.

Like a true competitor, Alec noted:

"It was actually so satisfying just to see other people just crumbling around us."

"Form had gone out the window... bodies everywhere, highs, lows, and raw emotions all on show all the time."

Arc Project 4 wasn't simply a test of fitness. It was a test of attention, resilience and the ability to keep moving through the unfamiliar. For 24 hours, every athlete remained in the same place. Mentally, many felt as if they had travelled somewhere very different.