Running News Daily

For seven relentless days, Débora Simas turned a treadmill inside a bustling shopping mall in Florianópolis, Brazil, into the stage for an extraordinary feat of endurance.

When the clock reached 168 hours at midday on Sunday, the 55-year-old ultramarathoner had covered an astonishing 866.21 kilometres — approximately 538 miles. That distance put her more than 20 kilometres beyond the previous Guinness World Records benchmark of 846.16 kilometres, set by New Zealand’s Emma Timmis in June 2024.

The achievement was the culmination of a challenge that demanded far more than simply running. For an entire week, Simas had to manage the relentless combination of physical fatigue, sleep deprivation, nutrition, recovery and the mental strain of repeatedly stepping back onto the treadmill.

Her temporary home was a tent positioned behind the treadmill, where she grabbed short periods of sleep and attended to essential recovery needs. Food, medical attention and other necessities had to be carefully fitted around the demands of the attempt, while a private bathroom inside the shopping centre provided the only place where she could briefly step away from the public eye.

This was not Simas’s first encounter with the unforgiving nature of seven-day treadmill running. In 2019, she completed 800.61 kilometres over the same 168-hour period at the Beiramar Shopping centre, setting a Brazilian and South American record at the time.  Her return seven years later was driven by a very different ambition: to go beyond the world’s best mark.

The preparation behind the attempt was equally remarkable. Simas reportedly spent two years preparing for the challenge while balancing two jobs, often training largely on her own. Every kilometre of that preparation ultimately became part of a much bigger test of patience, resilience and belief.

There were moments during the seven days when the body threatened to take control. At one stage, a severe cramp placed the attempt in jeopardy and forced members of her support team to intervene. Yet Simas recovered and continued, refusing to let one difficult moment derail an effort that had taken years to build.

Her final distance of 866.21 kilometres represents an average of about 123.7 kilometres per day, or roughly 5.15 kilometres every hour across the full 168-hour period. That figure includes the periods when she was required to stop for essential needs, making the scale of the accomplishment even more striking.

Simas now has the number that matters most: 866.21 kilometres. However, there is an important distinction between breaking the previous mark and having the Guinness title officially ratified. Guinness World Records notes that records can change before they are immediately reflected online, and official recognition depends on the verification process.

For Simas, though, the significance of the achievement goes far beyond a number on a leaderboard. Her journey was a battle against exhaustion, discomfort and the powerful urge to stop — a test in which mental strength became just as important as physical endurance.

“I had to face the sleepiness, the pain, the exhaustion, and moments when my head had to be stronger than my body,” she said.

After 168 hours, the treadmill finally fell silent. Débora Simas stepped away having transformed seven days of relentless running into one of the most remarkable endurance performances of her career — and, pending official verification, a new women’s world-best mark for distance covered on a treadmill in one week.