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 .
The effect of four weeks of supraphysiological growth hormone administration on the insulin-like growth factor axis in women and men. GH-2000 Study Group.
Measurements of serum insulin-like growth factor I ( IGF-I ) and related markers are routinely used in the diagnosis and treatment of GH deficiency and excess . The validity of these markers for assessment of exogenous GH exposure in healthy adults is , however , unknown . We therefore conducted a double blind , placebo-controlled GH treatment trial in 99 healthy subjects [ 49 women and 50 men ; mean + /- SE age , 25.6+/-0.6 (women)/25.7+/-0.6 yr ( men ) ] .  Blood  was collected weekly during a 4-week treatment period ( days 1 - 28 ) , and the subjects were subsequently followed for additional 8 weeks ( days 29 - 84 ) . The treatment arms included : I ) 0.1 IU/kg x day GH ( n = 30 ; GH 0.1 ) , II ) 0.2 IU/kg x day GH ( n = 29 ; GH 0.2 ) , and III ) placebo ( n = 40 ) . At baseline no gender-specific differences existed , except that the acid-labile subunit ( ALS ) levels were higher in females . Serum insulin-like growth factor I ( IGF-I ) levels in males receiving GH increased significantly through day 42 with no significant difference between the 2 doses . The absolute IGF-I response was significantly lower in females , and there was a clear dose-response relationship . ALS levels in males increased through day 30 ( P < 0.001 ) . In females ALS levels were only modestly increased on day 28 compared with those in the placebo group ( P < 0.02 ) . IGF-binding protein-3 ( IGFBP-3 ) levels in males increased significantly in the GH 0.1 and the GH 0.2 groups on day 30 ( P < 0.03 ) , whereas no solid IGFBP-3 increase was detected in females . IGFBP-2 levels decreased insignificantly during GH exposure in both genders . A gender-specific upper normal range for each analyte was arbitrarily defined as 4 SD above the mean level at baseline . On the basis of IGF-I levels alone , GH exposure in the GH 0.2 group was detected in 86 % of the males and in 50 % of the females on day 21 . On day 42 GH exposure was only weakly detectable in males and was not detectable in females . We conclude that 1 ) males are significantly more responsive than females to exogenous GH ; 2 ) the increase in IGF-I is more robust compared with those in IGFBP-3 and ALS ; 3 ) IGFBP-2 changes very little during GH treatment ; and 4 ) among IGF-related substances , IGF-I is the most specific marker of supraphysiological GH exposure
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 .