Brigid Kosgei of Kenya poses with her time after winning the Women's Bank of America Chicago Marathon while setting a world record of 2:14:04 on Sunday. Photo: Paul Beaty/AP

CHICAGO  Kenyan Eliud Kipchoge said he needs time to recover physically and mentally after becoming the first person to run a marathon in under two hours and has yet to decide if he will defend his title at next year's Tokyo Olympics.

World record holder Kipchoge smashed the two-hour barrier on a special course in Vienna on Saturday, finishing in one hour 59 minutes and 40 seconds in an unofficial attempt.

Before switching focus to his next challenge, which could include another Olympic appearance, the 34-year-old plans to recharge his batteries.

"I'll take three weeks of active rest and then I'll know what next. I'm taking normal meals with a lot of carbohydrates," he said in a question and answer session on his Facebook page.

"I'm concentrating purely on recovery and I have not given any thought for any other challenge. It's too early to tell (about the Olympics).

"I've never said that I'll no longer run (a marathon) but I'm going to first recover and then decide which race to run."

The sub-two hour marathon is widely regarded as the biggest achievement in athletics since Briton Roger Bannister broke the four-minute mile in 1954 - and was compared by Kipchoge himself to landing on the moon.

Kipchoge believes his run, which was organised and funded by the British chemical company INEOS and dubbed the INEOS 1.59 challenge, will encourage the next generation of athletes to push the boundaries in his home country.

The winning moment sparked jubilant scenes in Kenya as traffic was brought to a halt in Nairobi by hundreds of fans celebrating in front of a giant screen.

"It means a lot... I received a lot of messages. I saw people celebrating all over the country," Kipchoge said.

"Kenya will not be the same. It will be united and in future Kenya will be a running nation."

Reuters