American Alberto Salazar, who has coached some of the world's top distance runners including British multiple Olympic and world champion Mo Farah, has been banned for four years for doping violations.
The U.S. Anti-Doping Agency (USADA) said Salazar's punishment was for "orchestrating and facilitating prohibited doping conduct" as head coach of the Nike Oregon Project (NOP).
Reuters reports that the project was a camp designed primarily to develop U.S. endurance athletes.
The 61-year-old was quickly stripped of his accreditation for the world athletics championships in Doha by the sport's governing IAAF at the request of the U.S. track and field federation.
USADA said that Salazar, who also coached American Olympian Matthew Centrowitz among other top distance runners, trafficked banned performance-enhancing substance testosterone to multiple athletes.
Jeffrey Brown, who worked as a paid consultant endocrinologist for NOP on performance enhancement and served as a physician for numerous athletes in the training programme, also received a four-year ban.
Salazar said he would appeal USADA's decision, and sportswear giant Nike said in a statement that it would stand by him.
"I am shocked by the outcome today," Salazar said in a statement. "My athletes and I have endured unjust, unethical and highly damaging treatment from USADA."
"The Oregon Project has never and will never permit doping. I will appeal and look forward to this unfair and protracted process reaching the conclusion I know to be true. I will not be commenting further at this time."