Whoa! The 12-Hour World Record Run — On a Treadmill?!

Running far, wide, and long, including desert ultra running, set Susie Chan up for her treadmill world record attempt.

Photo by Phil Hill.

Susie Chan treadmill running, leading a Peloton session. Treadmill or Dreadmill, it's all about what you can do.

Photo courtesy of Peloton.

Posted Monday, March 3, 2025 2:02 pm

Excerpted from Trails and Tribulations: The Running Adventures of Susie Chan, Bloomsbury Sport Publishing*

The hours passed. I ran miles and miles. My fake it till you make it attitude was working. I had run through more difficult things in the past – difficult terrain, weathers and temperatures – but this was still tough. In different ways. Inevitably this is an event that’s tough, both physically and mentally. But there were factors I hadn’t considered. When you run outside, even on a track, there will be minor variations and unless you are terribly gifted, your pace will also fluctuate. Here I was locked in to one pace, each step being exactly the same as the last, over and over and over again. You end up using the same muscles in exactly the same way.

Having my close friends next to me as a distraction helped. If you do anything, anything at all – whether that be running, walking, sitting down, standing, gardening, reading, knitting – for 12 hours straight it becomes hard work purely through boredom. We had all sorts of things on the go to alleviate the tedium. I had curated a varied playlist, which was uplifting and loud, and at times people danced around me, making the atmosphere in the room fun. There were times when the space was buzzing and I fed off the energy.

The students were enjoying being part of this and, incredibly, loads of people came in to watch. They ranged from random people off the street, to people who had somehow heard about it and were driven by curiosity. Hannah recalls that more than a hundred people found their way through the campus to the lab that day. A few friends turned up unexpectedly, which was a lovely surprise. I was still struggling, but all these things combined certainly made me feel better at various moments. Having so many people invested helped fuel the part of my brain that can drive me to finish lines out of fear – fear of looking weak and fear of being a failure.

A screen had been set up in front of me to show me the Twitter stream. I was very active on the app back then and we had a hashtag – #SusieWRrun – on the go. Things started off quietly, but as the day went on more and more people were jumping on the hashtag and watching along online. The live feed was a fixed camera without sound, because we were unsure about the legality of broadcasting the music playing in the lab. It wasn’t riveting viewing; we had set this up as a way to record the whole effort and had not anticipated anyone actually wanting to tune in. Despite this, the stream audience grew and grew. At one point, thousands were watching.

Our hashtag started trending on Twitter. Messages started pouring in from all sorts of people from all over the place. They were on display on the screen ahead of me, generous and kind messages from people wishing me well and willing me on. Paula Radcliffe was tweeting about me. Paula Radcliffe!

People from all walks of life were coming in and talking to me next to the treadmill. This began as a happy distraction and something which was enjoyable. They had come in to find out what it was all about and offer support. As the day wore on, though, the conversations got harder and harder. It was the same sort of questions over and over: ‘Why are you doing this?’ The short answer is: Because I can. ‘How are you feeling?’ Increasingly awful. ‘What do you do if you need the loo?’ There’s a bucket. After about eight hours of this I quietly asked Shaun to act as a buffer, and physically stand between me and the people coming in, answering their questions and chatting on my behalf. I did not want to be rude or ungrateful, but eight hours of intermittent small talk was adding to the mental exhaustion.

Every so often the music would crank up and Charlotte or Shaun would bob around dancing with no self-consciousness at all to lift my spirits. The ups got shorter and shorter and the bravado started to wane. I had managed eight hours reasonably fine, but then suddenly everything dropped off a cliff. It was hard enough to pretend to the people in the room that everything was fine, but I had got to the stage where I did not want to speak to anyone at all. I was waving and smiling in the lab to everyone around, but as soon as I caught Shaun’s eye I did my best to convey silently how hideous it was starting to become.

I started to feel a little queasy. It was a specific queasy feeling too. The same sort of nausea that you get from reading a book in a car. This feeling while running was a new experience for me. What on earth is happening? I’ve run a lot further than this and been fine. Chris worked it out. About three feet in front of the treadmill – and me – was a blank wall and then, slightly to the left, the screen with all the tweets. And that was all I’d had to look at for the last eight hours. ‘Your body is detecting motion, but your eyes are not. You are seasick.’

Great.

This was not something that could be resolved, I would have to tough this out. My pace did not drop and I ploughed on, trying every so often to look to my left and my right and to my feet to mix things up a bit. Looking around gave my vision some depth of field. It was tricky because looking to my left or right made me feel unstable, but it did take the edge off the nausea momentarily.

Then, just when I thought that would be the toughest thing I would have to deal with, things took a bit of a turn….”

By Susie Chan

Editor’s Note: Since taking up running at the “late” age of 35, Susie Chan has completed the legendary Marathon des Sables more times than any other British woman and was one of the first women to finish all the World Marathon Majors and became the first European female and the first non-U.S. resident to finish the Badwater Ultra Cup. But she has also had her share of adversities, leaving a dysfunctional marriage, managing as a single mum, and tackling cancer treatment. Through it all, she always finds a reason to lace up her shoes, with her mantra: You never regret a run. As a Peloton tread instructor, Susie shares her love for running to members worldwide. And now — about those 12 hours on a treadmill …

Treadmills. Sometimes they’re called “Treads.” I’ve heard people call them “dreadmills,” say they never use them, and find them boring.
I beg to differ and here’s why — In the world I work in, treadmills are a place of joy, unity, community and, of course, walking and running.

Trails & Treads

Oh yes, I run through the countryside and am lucky enough to be surrounded by miles of trails. But many know me from coaching running classes on a treadmill. And there are benefits that far outweigh the fact that you’re not going anywhere.

The fact you are not going anywhere is a bonus!
• A treadmill is convenient, and there will be many times when convenience matters.
• The mismatching, thrown-on training outfit is suitable for the consistently dry and unimpacted-by-weather-conditions inside my garage. A treadmill run means there is no need to go to the trouble of trying to predict the somewhat unpredictable weather of wherever you lived, and when weather-predicting apps get it wrong. And if you’re not a fan of running in breath-stealing windchills, there’s no headwind to deal with on a treadmill.
• There is no need to sidestep pedestrians, wait for red lights to stop the traffic, or to keep an eye out for the person driving while texting.
• There’s the pleasant thoughtlessness of not having to think about a run route that suits your mileage goal. You get on, run, and, when you’re done, you hop right off, sweating in the privacy of your own home.

• A treadmill is a safe space. This includes those graduating from walking to running, or those coming back from an injury. You can take things at your own pace without having to worry about how far you’ve gone from your car or home. There is also a beauty in the consistency of it all, including pace; just lock in and go!
• Friends of different paces? That’s not a problem with treadmills. I get to share the joy of high-fiving people running at the same time, picking up the pace to the same playlist together, or taking in the same scenic 5K route on the screen.

Treadmill World Record?

Love or hate treadmills, most runners have used them, most runners have used treadmills, perhaps when there was no other option, as part of training, or as an easy way to get your workout in when time was tight.
I was like that, except when a treadmill turned into an opportunity to break a World Record for running.

When I began running, the farthest distance my brain could fathom as runnable was a half marathon. And 13 miles on a dreadmill? Not imaginable! Yet, one day, I would step on one with the singular goal of running the farthest a woman has ever treadmill-run nonstop — for 12 hours!

History & Training

My training history had included preparing for gruelling desert-run ultras, and I would often train at a nearby University’s Sports Science facilities; this facility had a “heat chamber,” a small climate-controlled room containing a treadmill. I used it to condition my body over the course of weeks to be able to withstand running in some of the hottest places on earth, a few exceeding 100 degrees. One year, a Sports Scientist who helped me prepare for my ultra marathons needed volunteers to help him conduct research that would form part of his PhD thesis. Few women had offered to help, so I did.
The help? He needed people to run 50 miles on a treadmill!
By taking blood and saliva samples as we ran, he measured, observed, noted, and monitored how the distance affected us. We also had a chart to capture our mental wellbeing, and he recorded the more straightforward, measurable things such as distance and calorific intake.

Having just completed an Ironman race, I finished the task feeling good, that running 50 miles on a treadmill was more bearable than I thought it would be. After chronicling the experience, including my 50-mile treadmill time, on social media, I thought the treadmill and I were finished. However, the response on social media told me otherwise:
Apparently, I was tantalisingly close to breaking a World record for Running on a treadmill.
A note of perspective: Not many people try these things!

Editor’s Note: Trails and Tribulations (256 pages, Bloomsbury Sports Publishing) by Susie Chan, available in hardcover, Kindle eBook, and Audible Audiobook (which has a fabulous 5-minute audio free sample) as of the October issue’s press time, quickly garnered 120 Amazon ratings soon after its release, with an average of 4.7 stars; Goodreads: 210 ratings with a 4.56-star average reader review. Ultramarathoner and New York Times bestselling author Dean Karnazes wrote: ‘Tells it all with an openness and honesty that comes from having endured some of the world’s most gruelling tests of endurance.’ From the Moroccan desert, the Peruvian jungle and the sweltering Death Valley, to Susie’s local South Downs and a running track in Tooting, her adventures take her across the globe. With Susie’s down-to-earth personality, refreshing attitude and wicked sense of humor, we learn the countless reasons she finds to push herself further and the life-changing opportunities running has given her. Her passion for the sport is infectious, and her story is a shining example to all in the running community and beyond. While available at the big-name places, please consider ordering through and supporting your local independent bookstore.