Some have suggested that growth hormone is a wonder drug ( 16 ) that results in ripped muscle ( 17 ) and provides stamina-increasing properties ( 18 ) .
The use of human growth hormone to improve athletic performance has recently received worldwide attention .
This practice , often called sports doping , is banned by most professional sports leagues and associations , including the International Olympic Committee , Major League Baseball , and the National Football League ( 13 ) .
However , a wide range of athletes , including those from baseball ( 46 ) , cycling ( 7 , 8) , and track and field ( 5 , 9 ) , have been implicated in or have confessed to illicit growth hormone use .
The Mitchell report ( 10 ) recently identified 89 Major League Baseball players who allegedly used performance-enhancing drugs , and some of these players have subsequently admitted to using growth hormone ( 11 , 12 ) .
Part of the attraction of using growth hormone as a performance enhancer has been that its use is difficult to detect .
The World Anti-Doping Agency , whose formation stemmed from the widely publicized doping sc and al of the 1998 Tour de France ( 13 ) , first used a blood test to detect exogenous growth hormone during the 2004 Olympic Games in Athens .
Although growth hormone is reportedly used to enhance athletic performance and has been called the most anabolic substance known ( 15 ) , its efficacy for this purpose is not well established .
Exogenous growth hormone therapy in growth hormonedeficient adults ( that is , those with growth hormone deficiency due to hypothalamic or pituitary defects ) results in increased lean mass and decreased fat mass ( 19 ) , and comparable body composition changes are seen in healthy elderly adults who receive growth hormone ( 20 ) .
Some experts , however , have suggested that the strength-enhancing properties of growth hormone among healthy adults have been exaggerated ( 15 ) .
Serious side effects , including diabetes , hepatitis , and acute renal failure , may occur in athletes using high-dose growth hormone ( 21 ) .
Furthermore , the use of growth hormone for athletic enhancement is not approved by the U.S. Food and Drug Administration , and the distribution of growth hormone for this purpose is illegal in the United States ( 22 ) .
We performed a systematic review of r and omized , controlled trials to determine the effects of growth hormone therapy on athletic performance in healthy , physically fit , young adults .
Our primary aim was to evaluate the effects of growth hormone on body composition , strength , basal metabolism , and exercise capacity .
In addition , we sought to synthesize the evidence on adverse events associated with growth hormone in the healthy young and assess the quality of the published literature .
Calorigenic effects of growth hormone: the role of thyroid hormones.
GH administration increases energy expenditure , independent of changes in lean body mass , in healthy , obese , and GH-deficient subjects . This may be causally linked to the well known GH-induced increase in peripheral T4 to T3 generation , but experimental data are sparse . In this study we have addressed whether 1 ) the calorigenic effects of GH administration could be reproduced by oral supplementation of T3 in a dose selected to mimic the GH-induced increase in peripheral T3 levels ; and 2 ) combined GH and T3 administration have a synergistic effect on resting energy expenditure ( REE ) .  Eight normal male subjects ( aged 21 - 27 yr ; body mass index , 21.11 - 27.17 kg/m2 ) were r and omly studied during four 10-day treatment periods with 1 ) daily sc placebo injections and placebo tablets , 2 ) daily sc GH injections ( 0.1 IU/kg x day ) and placebo tablets , 3 ) daily T3 administration ( 40 microg on even date s , 20 microg on uneven date s ) plus placebo injections , and 4 ) daily GH injections plus T3 administration . GH administration increased both free T3 ( FT3 ) levels [ mean + /- SE , 6.2 + /- 0.3 ( control ) vs. 7.3 + /- 0.5 ( GH ) pmol/L ; P < 0.05 ] and REE [ mean + /- SE , 1959 + /- 67 ( control ) vs. 2164 + /- 55 ( GH ) Cal/24 h ; P < 0.01 ] . T3 administration yielded comparable levels of FT3 ( 7.7 + /- 0.5 pmol/L ; T3 vs. GH , P = 0.37 ) , but did not increase REE ( 2015 + /- 48 Cal/24 h ; T3 vs. control , P = 0.23 ) . Combined GH and T3 administration increased REE to a level higher than that seen with T3 alone ( 2279 + /- 68 Cal/24 h ; T3 vs. GH plus T3 , P < 0.01 ) . Significant increments in serum levels of insulin-like growth factor I and insulin were recorded with GH administration , but not with T3 alone . Resting heart rate increased to a similar degree after GH administration and T3 supplementation , respectively . Tympanic temperature remained unaltered in all four studies . The results suggest that the calorigenic effect of GH is not mediated solely through increased conversion of T4 to T3
Some have suggested that growth hormone is a wonder drug ( 16 ) that results in ripped muscle ( 17 ) and provides stamina-increasing properties ( 18 ) .
The use of human growth hormone to improve athletic performance has recently received worldwide attention .
This practice , often called sports doping , is banned by most professional sports leagues and associations , including the International Olympic Committee , Major League Baseball , and the National Football League ( 13 ) .
However , a wide range of athletes , including those from baseball ( 46 ) , cycling ( 7 , 8) , and track and field ( 5 , 9 ) , have been implicated in or have confessed to illicit growth hormone use .
The Mitchell report ( 10 ) recently identified 89 Major League Baseball players who allegedly used performance-enhancing drugs , and some of these players have subsequently admitted to using growth hormone ( 11 , 12 ) .
Part of the attraction of using growth hormone as a performance enhancer has been that its use is difficult to detect .
The World Anti-Doping Agency , whose formation stemmed from the widely publicized doping sc and al of the 1998 Tour de France ( 13 ) , first used a blood test to detect exogenous growth hormone during the 2004 Olympic Games in Athens .
Although growth hormone is reportedly used to enhance athletic performance and has been called the most anabolic substance known ( 15 ) , its efficacy for this purpose is not well established .
Exogenous growth hormone therapy in growth hormonedeficient adults ( that is , those with growth hormone deficiency due to hypothalamic or pituitary defects ) results in increased lean mass and decreased fat mass ( 19 ) , and comparable body composition changes are seen in healthy elderly adults who receive growth hormone ( 20 ) .
Some experts , however , have suggested that the strength-enhancing properties of growth hormone among healthy adults have been exaggerated ( 15 ) .
Serious side effects , including diabetes , hepatitis , and acute renal failure , may occur in athletes using high-dose growth hormone ( 21 ) .
Furthermore , the use of growth hormone for athletic enhancement is not approved by the U.S. Food and Drug Administration , and the distribution of growth hormone for this purpose is illegal in the United States ( 22 ) .
We performed a systematic review of r and omized , controlled trials to determine the effects of growth hormone therapy on athletic performance in healthy , physically fit , young adults .
Our primary aim was to evaluate the effects of growth hormone on body composition , strength , basal metabolism , and exercise capacity .
In addition , we sought to synthesize the evidence on adverse events associated with growth hormone in the healthy young and assess the quality of the published literature .