LANZHOU, June 2 (Xinhua) -- More than 40,000 runners from 19 countries and regions participated in the 2019 Lanzhou International Marathon on Sunday competing in a city with an average altitude of over 1500 meters.

Athlete Motlokoa Clement Nkhabutlane, 34, from Lesotho, said that high altitude posed as a challenge for runners.

"Although the altitude of Lanzhou is basically the same as that of my hometown, it is still a challenge to finish the race," said Motlokoa.

A training expert from Chinese State General Administration of Sports said there is a negative correlation between altitude and running speed.

"With every 100m higher in the altitude, six more seconds will be needed to run 10,000, "Chen Geng said. "Runners have to run against the effect of high altitude, dry weather and strong sunlight in Lanzhou Marathon."

Lanzhou has been recognized as both the IAAF Gold Label Race Event and the CAA Gold Medal Race Event, the only "double gold" marathon event in northwest China.