Ugandan long-distance runner Jacob Kiplimo has been stripped of his world record in the half-marathon.
Kiplimo, 25, won a bronze medal at the Paris 2024 Olympics in the men's 10,000 metres.
In February 2025, he won the Barcelona Half Marathon and, in the process, smashed the previous half-marathon record by running a time of 56 minutes and 42 seconds.
The record had been held by Ethiopia's Yomif Kejelcha, who ran a time of 57:30 in Valencia in October 2024.
Kiplimo then capped off an incredible 2025 by winning the Chicago Marathon in a personal-best time of 2:02.23, having finished in second place in the London Marathon.
Kiplimo won the 2025 Chicago Marathon (Image: Getty) However, World Athletics have confirmed to Runner's World Spain that the Ugandan's half-marathon world record has been wiped from the books.
It is said to have been deemed that Kiplimo's time was 'achieved with aids that violated the regulations'.
The report adds that Kiplimo 'took advantage of the slipstream of the nearby lead car that opened the race a few metres behind him to run with less air resistance'.
The lead vehicle is used to control the pace of each race and provides a reference point for the lead athletes, as well as being fitted with a timing clock to help ensure accurate timing splits.
You can see footage of Kiplimo's now unratified world record time below.
As per Point 6.3 of World Athletics' Technical Rules, updated as of 2020, there are a number of definitions for what is classed as assistance to athletes during races.
It states the following is not permitted: "Pacing in races by persons not participating in the same race, by athletes lapped or about to be lapped or by any kind of technical device (other than those permitted under Rule 6.4.4 of the Technical Rules).
The aforementioned Rule 6.4.4 only mentions 'heart rate or speed distance monitors or stride sensors or similar devices carried or worn personally by athletes during an event, provided that such device cannot be used to communicate with any other person'.
Therefore, Kejelcha's time of 57:30 has been restored to the record books, while Kiplimo will have several opportunities to break it again during 2026.