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
DATA SOURCES: MEDLINE, EMBASE, SPORTDiscus, and Cochrane
Collaboration databases were searched for English-language studies
published between January 1966 and October 2007.
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.