A Brazilian man with a penchant for sporting records has broken a new one after tackling the most boring physical challenge he could dream up: running on a treadmill for 24 hours.

Pepe Fiamoncini ran 188 kilometres – more than four marathons – on a treadmill at an open-air gym on Rio de Janeiro's Ipanema beach.

Once validated by officials who watched the challenge via live stream, the feat will earn him a third Guinness World Record.

The 35-year-old took only short breaks to change his shoes or go to the bathroom.

"I define myself with one word: curious. I'm curious about my abilities," Fiamoncini said.

He said he started doing sport during the Covid pandemic, when he signed up for an Iron Man, a long-distance triathlon, which he saw as the "pinnacle of human capacity."

After conquering that he did an Ultraman – more than double the distance – and set his sights on Guinness World Records.

The first record he broke was in May 2023, when he crossed the Uyuni salt flats in Bolivia, covering 170 km in a little over 33 hours.

The vast white expanse sits at 3,600 meters above sea level, with extreme temperatures ranging from 30 degrees Celsius during the day to -10 degrees Celsius at night.

The previous record was 55 hours.

Having conquered such extremes he sought to challenge his mental limits.

"So I thought, what's the most boring thing I hate? Running non-stop in the same place."

In October, Fiamoncini set his second Guinness record when he ran 110 km in 12 hours on a treadmill as a warm up for the challenge he finished Thursday. (AFP)