THERE IS NO SCIENTIFIC EVIDENCE THAT GROWTH HORMONE IS PERFORMANCE ENHANCING
Bidlingmaier, M., Wu, Z., & Strasburger, C. J. (2001). Doping with growth hormone. Journal of Pediatric Endocrinology and Metabolism, 14, 1077-1083.
"Triggered by the Olympic games in Sydney last year, many articles in the press suggested that recombinant human growth hormone (hGH) is one of the most popular performance enhancing drugs used by athletes. However, any hard facts on hGH abuse were provided by Australian customs officers--and not by laboratory assessment. The lack of an official test for hGH doping together with the widespread rumors on its tremendous beneficial effects seem to make this compound attractive for athletes. From a scientific point of view, there are two major questions about this issue: First, as there is no controlled study demonstrating a profound effect of hGH administration on workload capacity in healthy adults, why do athletes use hGH? Second, how could the application of a substance naturally occurring in the human body be detected? Both aspects are discussed in this article".
Implication. As of 2001, there is no scientific evidence that exogenous growth hormone is performance enhancing in healthy adults, let alone athletes.