A fleet-footed Japanese centenarian raced into the Guinness World Records reference book on Wednesday and declared himself a "medical marvel" as he continues to stalk sprint king Usain Bolt.

Hidekichi Miyazaki, dubbed "Golden Bolt" after the fastest man on the planet, clocked 42.22 seconds in Kyoto to set a 100 metres world record in the over-105 age category -- one for which no mark previously existed -- a day after reaching the milestone age.

"I'm not happy with the time," the pint-sized Miyazaki told AFP in an interview after recovering his wind. "I started shedding tears during the race because I was going so slowly. Perhaps I'm getting old!"

Indeed, so leisurely was his pace that Bolt could have run his world record of 9.58 four times, or practically completed a 400 metres race -- a fact not lost on Miyazaki.