World Athletics recently made a decision: it has officially refused to ratify Uganda star Jacob Kiplimo's 56:42 performance at the Mitja Marató de Barcelona on February 16, 2025. That means the performance, once hailed as a historic breakthrough in the men's half marathon that lowered the previous mark by a remarkable 48 seconds, has been voided. Ethiopia's Yomif Kejelcha's 57:30 at the Valencia Half Marathon in October 2024 will remain the world record. Core of the controversy: aerodynamic advantage and the rules' red line After a lengthy review, World Athletics' Record Ratification Committee determined that Kiplimo received "external assistance" in the Barcelona race which breached competition rules. The central reason for the record being annulled was "running too close behind a vehicle." According to World Athletics, during the race Kiplimo spent extended periods running directly behind the lead vehicle (timing car). Although World Athletics' rules do not specify a precise distance in metres between the lead vehicle and the leading pack, broadcast footage from the race showed Kiplimo repeatedly positioned unusually close to the vehicle. At that proximity, the wake created by the vehicle produces a slipstream effect that significantly reduces air resistance for the runner. This drafting effect can save substantial energy at high speed. The committee concluded that this non-natural aerodynamic advantage violated the principle of fair competition. In addition, under Article 6.3 of the World Athletics competition rules (in force since the end of 2020), the use of "non-competitors, lapped athletes or any technical device to provide pacing assistance" is prohibited, and any form of "mechanical assistance" is banned. Beyond gaining from drafting, World Athletics also cited another infringement: Kiplimo received on-course coaching from his coach during the race. A long wait, and the dust settles Rumours that the record might not stand had been circulating for months. During that period, World Athletics ratified several world records set after the Barcelona performance, yet remained silent specifically about the Barcelona result, which had already prompted industry speculation. On Monday this week, World Athletics formally published a list of newly ratified world records, including Grant Fisher's indoor 5000m world record set on February 14, 2025, and U20 records by Phanuel Koech and Isaac Beacroft. At the same time, Kiplimo's 56:42 was officially confirmed as "not ratified." This decision means that, although Kiplimo's name will not be erased in the way a doping violation would remove it, on the official record lists Kejelcha's 57:30 (2024) remains the benchmark for the men's half marathon.