It's classified as a PED. Absurd but true.
According to the United States Anti-Doping Agency, which follows WADA’s rules, cannabis can cause muscle relaxation and reduce pain after workouts while also decreasing anxiety and tension, “resulting in better sport performance under pressure.” WADA and the USADA also say that pot increases focus and risk-taking behaviors, “allowing athletes to forget bad falls or previous trauma in sport, and push themselves past those fears in competition.” However, the organizations also cite “health risks,” and note that pot’s illegal status in most states and countries “does not exhibit the ethics and moral judgment that upholds the spirit of sport.”
