The efficacy of ergogenic agents in athletic competition. Part II: Other performance-enhancing agents

To summarize the literature describing the epidemiology, pharmacology, efficacy, and adverse effects associated with growth hormone (GH), caffeine, aerobic metabolism facilitator (AMF), and sympathomimetic use among athletes.

Relevant articles were identified from a MEDLINE search using the search terms "Doping in Sports," "Blood," "Caffeine," "Cocaine," "Erythropoietin," "Somatotropin," and "Sympathomimetics (exploded)." Additional references were found in bibliographies of these articles.

We reviewed studies of ergogenic drug (ED) use among athletes. Interpretation of these studies is difficult because of poor research design and the paucity of information available. This necessitated the inclusion of many anecdotal or conjectural reports in our review.

There are no studies documenting an ergogenic effect associated with GH use in humans or animals. It is still unknown whether GH abuse causes adverse effects in healthy adults, although GH-induced acromegaly has been suspected. Amphetamines, cocaine, and caffeine are thought to improve performance via enhanced concentration among athletes. Amphetamines and cocaine may increase aggressiveness. The ergogenic effects of other sympathomimetics including ephedrine and phenylpropanolamine are unclear. AMFs (e.g., blood doping, epoetin) enhance aerobic metabolism and endurance by increasing the oxygen-carrying capacity of the blood. Risks associated with excessive AMF use include increased blood viscosity and clotting.

Athletes view EDs as an essential component for success. Without adequate intervention measures, ED abuse is likely to continue unchecked.