According to the Japan Anti-Doping Agency, Yasuhiro Suzuki spiked the drink of rival Seiji Komatsu with an anabolic steroid at last September’s national championships, causing him to fail a doping test.
The Japan Canoe Federation began investigating after Komatsu tested positive but denied taking drugs. The federation said Komatsu's suspension and records that had been stripped have been restored.
After Komatsu tested positive, Suzuki admitted putting a muscle-building supplement containing the banned steroid methandienone in his drink, ESPN reported.
It is the first time in Japan that an athlete failed a doping test because of deliberate contamination, JADA said.
Suzuki and Komatsu were considered among the top candidates to represent Japan in the 2020 Tokyo Olympics, ESPN reported.