CAS finds Koki Ikeda’s explanation for his blood values plausible

The Court of Arbitration for Sport (CAS) has published the full decision in the Koki Ikeda case. Ikeda is a Japanese race walker and Olympic silver medallist. The 30-page opinion was issued on 23 October 2026, and in it the three-member panel finds plausible the athlete’s explanation for his abnormal blood values: gastrointestinal bleeding, exercise-induced intravascular haemolysis and a shift in plasma volume. Ikeda had appealed to CAS against the ruling issued against him.

what the athlete argued

The Athletics Integrity Unit (AIU) charged Ikeda in June 2024 with a doping violation based on a review of his athlete biological passport (ABP). The abnormal values come from tests carried out in 2023. The AIU maintained that they were due to blood withdrawal and reinfusion, in other words blood doping, in time for the 2023 World Athletics Championships.

Ikeda and his team put forward a different explanation: that the 2023 values were the result of gastrointestinal bleeding and his subsequent recovery to a normal state. In the text of the decision, the CAS panel concluded as follows:

“In the Panel’s view, and taking into account the considerations explained above, the alternative physiological scenario put forward by the athlete to explain his abnormal blood values is plausible.”

The three factors the panel found established

According to the panel, the athlete established three factors to explain the anomalies in sample 25: gastrointestinal bleeding, exercise-induced intravascular haemolysis and exercise-induced plasma volume shift. Several experts corroborated that a combination of them could explain the abnormal values. The tribunal also considered that World Athletics’ objections to those experts’ reports do not rule out the plausibility of the athlete’s explanations.

The reasoning includes a detail about his activity: Ikeda kept training between April and June 2023, although with fatigue, despite the anomalies in sample 25. For the panel, this is consistent with a gradual loss of blood and not with a massive withdrawal.

“As explained, the athlete established the existence or occurrence of the three factors he put forward to explain the anomalies in sample 25 (gastrointestinal bleeding, exercise-induced intravascular haemolysis and exercise-induced plasma volume shift). Not one, but several experts corroborated that a combination of the three established factors could explain the abnormal values in sample 25, and the objections to their reports raised by WA do not, in the Panel’s view, exclude the plausibility of the athlete’s explanations. The fact that the athlete continued training in the period from April to June 2023, although with fatigue, despite the anomalies in sample 25, is consistent with a gradual loss of blood and not with a massive withdrawal of blood.”

How the case began: from the charge to the four-year ban

In November 2024 it was reported that the AIU had provisionally suspended Ikeda, then aged 26, after detecting an anomaly in his biological passport data. As explained at the time, that suspension was the precautionary measure required by the World Athletics protocol when the violation was not detected in an anti-doping test flagging the prohibited substance. By November 2024 he had already been notified of the start of disciplinary proceedings and had to justify the origin of the abnormal figures to avoid a definitive ban.

Ikeda denied the charge and the case went to the Disciplinary and Appeals Tribunal, which had to decide before the Japanese National Championships on 16 February 2025, in which the athlete wanted to compete. On Friday 14 February 2025 it was reported that he had been banned for four years by the Athletics Integrity Tribunal over anomalies in his biological passport, although without losing any of his major medals. According to that report, he had breached Rule 2.2 of the World Athletics anti-doping rules, for “use or attempted use of a prohibited substance or method”. The anomalies were detected in blood samples collected on 20 June 2023, and his results between that date and 1 November 2024 were annulled. It was stated at the time that he could appeal to the Court of Arbitration for Sport.

Who is Koki Ikeda: medals and career

Ikeda was Olympic silver medallist in the 20 km walk at the Tokyo 2020 Games. In that race Spain’s Álvaro Martín finished fourth, just missing out on a medal. He also won silver at the 2022 World Championships in Oregon (Eugene, United States).

In 2024 he won the Japanese National Championships, which sent him straight to the Games, and took silver in the mixed relay at the World Team Championships in Antalya in April. At the Paris 2024 Games he finished seventh in the 20 km walk. Before his provisional suspension he competed in the 10,000 m walk in Yamaguchi, where he finished third, a month before the measure became known.