One of the most decorated long-distance runners in modern athletics history, Kenyan elite Peres Jepchirchir, has been provisionally suspended by the independent Athletics Integrity Unit (AIU) following an adverse analytical finding for the banned performance-enhancing substance erythropoietin (EPO) in an out-of-competition drug sample. The specimen in question was collected from the 33-year-old athlete while she was training in Kenya in the lead-up to her dominant victory at the 2026 Sydney Marathon on 30 August. Jepchirchir crossed the Sydney finish line in a blistering time of two hours, 18 minutes and 31 seconds, finishing a full three minutes and 40 seconds ahead of her closest rival and fellow Kenyan Irene Chepet Cheptai. The Sydney event, which earned status as the seventh Abbott World Marathon Major in 2025, was the latest in a long string of landmark career triumphs for Jepchirchir: her resume also includes gold at the 2020 Tokyo Olympic women’s marathon, a 2025 World Championships marathon title secured in Tokyo, major marathon wins in New York (2021), Boston (2022) and London (2024), plus four separate women’s half-marathon world record breaks spanning 2017 and 2020. EPO, a naturally occurring renal hormone that triggers red blood cell production, is classified as a banned substance in athletic competition when administered exogenously, as artificially elevated red blood cell counts boost oxygen delivery to working muscles to drastically enhance endurance performance. The injected form of synthetic EPO is only detectable in urine or blood matrices for a narrow time window, making out-of-competition targeted testing a critical tool for anti-doping authorities to catch use of the substance. The AIU’s provisional suspension bars Jepchirchir from all official athletics competition and sanctioned events pending the completion of a full formal anti-doping review process, during which the athlete retains the right to contest the finding and request analysis of her backup sample.