Final answer:
Athletes selected for doping controls must immediately stop all activities and comply with the doping control process, overseen by organizations like the World Anti-Doping Agency to preserve the spirit of sport and prevent cheating.
Step-by-step explanation:
Once an athlete is selected for doping controls, they must cease training, competing, or any warm down activities immediately. Doping controls are conducted to ensure the integrity of sports and are upheld by rules set by organizations such as the World Anti-Doping Agency. These rules are put in place to catch athletes who use drugs and maintain fair play and the spirit of sport. Athletes are often required to stay within sight of a doping control officer from the moment they are notified until the completion of their test, which ensures that there is no opportunity for tampering with the sample.