Japanese athlete Kenichi Ito maintained his status as the world's fastest man on four limbs as he ran a 100-metre track in Tokyo in 17.47 seconds, breaking his own record from 2008 of 18.58 seconds.
Kenichi Ito runs modelling his style on how a monkey moves.
The 30-year-old hopes that one day racing on four legs will become an official track and field competition.
Teary-eyed, Ito was overjoyed with his new world record result.
"One day, I am certain that all sprinters will be running on all fours. That is my dream," he said.
Ito has been training for nine years, studying primates' movements through books, videos and visiting the zoo frequently.
At home or at work he moves mainly in all fours as part of his daily training.
Working as a janitor, he says it helps him get better by wiping the floors on all fours instead of using a mop.
"More than one second faster is a huge improvement, that was all the thoughts that were crossing my mind as he was crossing the final line," said Guinness judge Carlos Martinez who witnessed the challenge.
Ito hopes someday he will beat Usain Bolt's record of 9.58 seconds, encouraging sprinters of the world to try running on all fours.