Britain's world women's marathon record holder Paula Radcliffe and double Olympic champion Mo Farah are among the elite runners who have pounded the dirt tracks criss-crossing the lush green hillsides perched some 2,400 metres above sea level.
However, fears of a repeat of the bloody unrest that followed the last presidential election in 2007 and forced the evacuation of some foreign athletes is scaring international runners away.
"They won't confirm (hotel bookings). They are saying 'we would like to come but we will wait and see'," said Wilson Kipsang, Olympic bronze medallist and 2012 London Marathon winner, who also owns the newly-opened Keellu hotel in Iten.
Hotel owners say the number of elite athletes booked in for March are down by around half compared with 2012 when runners from Britain, the United States and Scandinavia descended on Iten in the run-up to the London Olympics.
"Foreign clubs are often sending us e-mails inquiring about elections and safety," said Simoens Peter, who runs Iten's popular Kerio View hotel.
Peter said elite athletes from Belgium, Sweden and Norway were among those who have reserved a space at the hotel but were unwilling to pay the customary 50 percent deposit.
"We have no other choice but to accept it," Peter said. "We just had a German running club cancel. They have one group here now and another was due to come in March but they pulled out."
The Rift Valley was the epicentre of ethnic clashes that followed opposition claims that President Mwai Kibaki's re-election was a sham. Mobs from the rival Kalenjin and Kikuyu communities set up roadblocks, burned houses and killed with stones and machetes.
Local athletes were also caught up in the violence that killed more than 1,200 people nationwide.
Lucas Sang, the 1988 Olympics 4x400 relay finalist, was killed during a mob fracas in Eldoret, while marathon runner Wesley Ngetich was shot by a poisoned arrow near the Maasai Mara game reserve. Training was disrupted for nearly two months.
Western diplomats and political analysts say violence cannot be ruled out this time. Front-runners in the presidential vote Prime Minister Raila Odinga and former Finance Minister Uhuru Kenyatta are running neck-and-neck in the polls.
Luke Kibet, Kenya's 2007 world marathon champion and friend of murdered Sang, was knocked unconscious and concussed by a stone thrown during riots in Eldoret on New Year's eve in 2007.
A few weeks later he was forced to fire his pistol in the air when a mob a road and approached him with machetes.
"I think we will be safe this time around," said Kibet, who gave refuge to women and children in his house during Kenya's worst outbreak of violence since independence in 1963.
Kibet's optimism is shared by fellow Kenyan champions. They who say the authorities are watching out for inter-tribal hate speech in the run-up to the poll and plan to bolster security force numbers in potential flash-points.
"It has really put people at ease," said Kipsang. In a vote of confidence, he said, most Kenyan athletes, many of whom have amassed personal fortunes beyond most Kenyans' dreams, were staying put rather than training abroad.
Deep-seated tensions, primarily over land ownership, have simmered since independence between the local Kalenjin tribe and the Kikuyu community, who obtained tracts of Rift Valley land when the British colonial masters left.
In a country where political support tends to follow ethnic lines rather than ideology, those animosities occasionally flare up, notably around elections.
This vote, though, may be different in the Rift Valley. Uhuru Kenyatta, a prominent Kikuyu, has formed an alliance with Rift Valley favourite William Ruto, a Kalenjin.
Both men face charges of crimes against humanity at the International Criminal Court, accused of masterminding the post-election violence five years ago when they backed rival candidates.
"I don't hear any fears expressed by the athletes that things are going to get out of hand," said Brother Colm O'Connell, who coaches Olympic 800 metres champion and world record holder David Rudisha.