Kenyan Trail Running Champion Joyline Chepngeno Slapped With 2-Year Ban for Doping Offense
Trail running champion Joyline Chepngeno has been handed a two-year ban after testing positive for the prohibited substance Triamcinolone Acetonide.
The sanction follows her victory at the 2025 Sierre-Zinal, one of the world’s most prestigious mountain races.
The Athletics Integrity Unit (AIU) confirmed that all of her results from August 9, 2025, onward have been annulled, including her Sierre-Zinal win and her triumph at the 2025 OCC just two weeks later.
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The AIU has banned Joyline Chepngeno (Kenya) for the Presence/Use of a Prohibited Substance (Triamcinolone acetonide) for 2 years from 8 September 2025. DQ results since 9 August 2025.
— Athletics Integrity Unit (@aiu_athletics) September 9, 2025
Details here: https://t.co/y4zy3RzTHe pic.twitter.com/IZDdg6Cgmi
Chepngeno’s fall from grace comes just a year after her breakout victory at the 2024 Sierre-Zinal and following a string of major wins in 2025, including the Marathon du Mont-Blanc.
In its official statement on September 9, the AIU explained: “On the basis that the Athlete has admitted the Anti-Doping Rule Violations under Rule 2.1 ADR and Rule 2.2 ADR, in accordance with Rule 10.2.1 ADR, the AIU confirms by this decision the following Consequences for a first Anti-Doping Rule Violation: a period of Ineligibility of two (2) years commencing on 8 September 2025; and disqualification of the Athlete’s results on and since 9 August 2025, with all resulting consequences, including the forfeiture of any titles, awards, medals, points, prizes and appearance money.”
Chepngeno admitted that she had received an injection in her knee in July 2025 to relieve pain but claimed she was unaware the treatment contained a banned corticosteroid.
She expressed regret for what she described as an honest mistake, submitting an Admission of Anti-Doping Rule Violations and Acceptance of Consequences Form to the AIU.
Race Results Overturned
Following the AIU decision, the Sierre-Zinal race organization confirmed Chepngeno’s disqualification and declared Kenyan runner Caroline Kimutai the official 2025 women’s champion.
The updated podium now sees American Katie Schide elevated to second place and Switzerland’s Maude Mathys to third.
This is not the first time Mathys has been linked to doping controversies. In 2015, she received a warning—though not a suspension—after testing positive for clomifene, which she had reportedly taken unknowingly without a Therapeutic Use Exemption.
Coach and Team Sanctioned
The scandal has also extended to Chepngeno’s coach, Julien Lyon, who has been sanctioned by Sierre-Zinal organizers.
Lyon, who leads the Milimani Runners Kenyan trail running team, has now been involved in two doping cases at the same race in just three years.
In 2022, his athlete Mark Kangogo tested positive for Norandrosterone and Triamcinolone Acetonide, receiving a reduced one-year ban after admitting the violation early.
Lyon and all athletes associated with Milimani Runners have been banned from future editions of Sierre-Zinal. The move underscores the event’s zero-tolerance stance toward doping, particularly given repeated violations linked to the same training group.
The implications for Kenyan distance running are serious. In 2024, Kenya led the world in doping sanctions, with more violations than India and Russia, fueling debate about systemic doping in the nation’s endurance programs.