Doping is the use of illicit chemicals by athletes to improve their performance. There are five sorts of prohibited medications known as doping classifications. Stimulants and hormones are the most prevalent. Other common drugs include substances that increase blood flow to muscles (causing a "rush" when used regularly), painkillers for muscle injuries, and anticonvulsants to control seizures. Stimulants include caffeine, taurine, and ephedrine. They can be taken orally or by injection. Caffeine increases the amount of calcium in the bones, thereby increasing bone density. Taurine promotes growth and development of cells, improves vision, and regulates heart function. Ephedrine stimulates the sympathetic nervous system, which controls heart rate and energy production. This drug has many names including ma huang, mao huang, and myrmecetium. Hormones include anabolic steroids, human growth hormone (hGH), erythropoietin (EPO), insulin-like growth factor 1 (IGF-1), and testicular hormones. Anabolic steroids increase the number of new cells produced by the body's natural repair processes. This includes bone cells and muscle cells. Because these cells are needed for healing after injury or surgery, anabolic steroids are useful in treating athletes who have problems recovering from trauma or surgery.