Jacob Kiplimo’s Half-Marathon World Record Ratified 11 Days After Yomif Kejelcha Broke It

World Athletics ratified Jacob Kiplimo’s 57:20 half-marathon world record on Thursday, 179 days after he ran it in Lisbon. Yomif Kejelcha had beaten it 11 days earlier, running 56:51 in Buenos Aires, and that mark is still waiting on a ruling of its own. The announcement covered three records and gave no reason for the wait.

The Records That Went Through First

Kiplimo ran the London Marathon on April 26, seven weeks after Lisbon, and finished third in 2:00:28. The two world records set in that race, Sabastian Sawe’s 1:59:30 and Tigst Assefa’s 2:15:41, were ratified on July 23, 88 days later and six weeks before his own. Both are road records, run on measured courses, subject to the same verification as a half-marathon. That same batch cleared Mondo Duplantis’s 6.31m pole vault from Uppsala on March 12, four days after Lisbon.

The two track marks announced alongside Kiplimo on Thursday were quicker still. Ja’Kobe Tharp’s 12.75 in the 110m hurdles, run on June 10 at the NCAA Championships in Eugene, took 85 days. Emmanuel Wanyonyi’s 2:11.83 over 1,000m in Monaco on July 10 took 55.

The Time That Was Left Out

In Thursday’s release, World Athletics said the Lisbon run “took 10 seconds off the previous ratified world record of 57:30,” the mark Kejelcha set in Valencia in October 2024. That comparison skips over a faster time.

Kiplimo covered the distance in 56:42 in Barcelona on Feb. 16, 2025, the first time a man had gone under 57 minutes, and World Athletics deliberated for almost a year before rejecting it in February. Broadcast pictures showed him 10 to 15 meters behind the lead car for long stretches, near enough to engage Article 6.3.1, which bars pacing help from anything other than a wearable device. Until Thursday, that ruling had appeared only in a footnote to a race report.

Back to Lisbon

Kiplimo returned to Lisbon on March 8 and won in 57:20. No pacemakers were used. Nicholas Kipkorir stayed with him through 5K in 13:28, 10K in 27:00 and 15K in 40:52, according to World Athletics’ race report. The next 5K took 13:31 and settled it. Kipkorir finished second in 58:08, 48 seconds back.

It was Kiplimo’s second world record on that course. He ran 57:31 in Lisbon in 2021, and that mark stood until Kejelcha took it down by a second in Valencia.

What Happens to 56:51

Kejelcha’s 56:51 now goes into the same process, and his course adds a step. Buenos Aires used a new layout in 2026, with the highway sections replaced by Avenida 9 de Julio and Avenida Libertador, so the route he ran with a device on each wrist needs certification of its own. Under the criteria published by AIMS, whose measurers World Athletics recognizes, a course has to be validated from the lead vehicle and then re-measured, preferably by a different approved measurer, as close to race day as practical.

He has waited before. His 10K road record of 26:31, set in February 2025, went more than 15 months before World Athletics made it official. Until the governing body rules on Buenos Aires, 57:20 stands as the men’s half-marathon world record. Kejelcha races next at the Valencia Marathon on Dec. 6.