Appears to be a generally fair summery. Gh has greater effects as a hormone that can improve recoup vs directly impact performance per se, can have uses healing connective tissue injuries*, and when combined with other hormones/drugs, appears to have synergism. However, it's not as well studied as it needs to be, and there is a risk to benefit that must be taken into account as with any drug.
* = for discussion on that see:
http://www.shadowspear.com/vb/showthread.php?t=10110&highlight=growth+factorsSystematic review: the effects of growth hormone on athletic
performance.Ann Intern Med. 2008 May 20;148(10):747-58. Epub 2008 Mar 17.
Liu H, Bravata DM, Olkin I, Friedlander A, Liu V, Roberts B, Bendavid E, Saynina O, Salpeter SR, Garber AM, Hoffman AR.
Santa Clara Valley Medical Center, San Jose, California 95128, USA. hauliu@stanford.edu
BACKGROUND: Human growth hormone is reportedly used to enhance athletic performance, although its safety and efficacy for this purpose are poorly understood.
PURPOSE: To evaluate evidence about the effects of growth hormone on athletic performance in physically fit, young individuals.
DATA SOURCES: MEDLINE, EMBASE, SPORTDiscus, and Cochrane Collaboration databases were searched for English-language studies published between January 1966 and October 2007.
STUDY SELECTION: Randomized, controlled trials that compared growth hormone treatment with no growth hormone treatment in community-dwelling healthy participants between 13 and 45 years of age.
DATA EXTRACTION: 2 authors independently reviewed articles and abstracted data.
DATA SYNTHESIS: 44 articles describing 27 study samples met inclusion criteria; 303 participants received growth hormone, representing 13.3 person-years of treatment. Participants were young (mean age, 27 years [SD, 3]), lean (mean body mass index, 24 kg/m2 [SD, 2]), and physically fit (mean maximum oxygen uptake, 51 mL/kg of body weight per minute [SD, 8]). Growth hormone dosage (mean, 36 microg/kg per day [SD, 21]) and treatment duration (mean, 20 days [SD, 18] for studies giving growth hormone for >1 day) varied. Lean body mass increased in growth hormone recipients compared with participants who did not receive growth hormone (increase, 2.1 kg [95% CI, 1.3 to 2.9 kg]), but strength and exercise capacity did not seem to improve. Lactate levels during exercise were statistically significantly higher in 2 of 3 studies that evaluated this outcome. Growth hormone-treated participants more frequently experienced soft tissue edema and fatigue than did those not treated with growth hormone.
LIMITATIONS: Few studies evaluated athletic performance. Growth hormone protocols in the studies may not reflect real-world doses and regimens.
CONCLUSION: Claims that growth hormone enhances physical performance are not supported by the scientific literature. Although the limited available evidence suggests that growth hormone increases lean body mass, it may not improve strength; in addition, it may worsen exercise capacity and increase adverse events. More research is needed to conclusively determine the effects of growth hormone on athletic performance.
