Tokyo Olympic 800m champion Athing Mu-Nikolayev has parted ways with coach Bobby Kersee, according to a report by LetsRun’s Jonathan Gault. She had been coached by Kersee in Los Angeles since November 2022. Kersee told LetsRun that Mu-Nikolayev has moved to Dallas with her husband. Kersee added that it was “a blessing” to coach Mu. Mu-Nikolayev has yet to announce a new coach. Mu-Nikolayev raced the 800m four times in 2025 and finished with a season’s best of 1:59.79. She reached the semifinals of the U.S. Championships.