Final answer:
Blood doping is the practice of injecting supplemental red blood cells (RBCs) into an individual to enhance performance in a sport. It can increase aerobic capacity, but it is illegal and carries risks such as increased blood viscosity and the potential for transmission of blood-borne pathogens.
Step-by-step explanation:
Blood doping is the practice of injecting supplemental red blood cells (RBCs) into an individual to enhance performance in a sport. When reinfused, the additional RBCs deliver more oxygen to the tissues, increasing aerobic capacity. However, blood doping is illegal in sports due to the risks involved. It can significantly increase blood viscosity and the potential for transmission of blood-borne pathogens if the blood is collected from another individual.