RESULTS Body cell mass was correlated with all measures of performance at baseline .
Growth hormone significantly reduced fat mass , increased lean body mass through an increase in extracellular water , and increased body cell mass in men when coadministered with testosterone .
Growth hormone supplementation influenced body composition and increased sprint capacity when administered alone and in combination with testosterone .
BACKGROUND Growth hormone is widely abused by athletes , frequently with and rogenic steroids .
Its effects on performance are unclear .
OBJECTIVE To determine the effect of growth hormone alone or with testosterone on body composition and measures of performance .
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
RESULTS Body cell mass was correlated with all measures of performance at baseline .
Growth hormone significantly reduced fat mass , increased lean body mass through an increase in extracellular water , and increased body cell mass in men when coadministered with testosterone .
Growth hormone supplementation influenced body composition and increased sprint capacity when administered alone and in combination with testosterone .
BACKGROUND Growth hormone is widely abused by athletes , frequently with and rogenic steroids .
Its effects on performance are unclear .
OBJECTIVE To determine the effect of growth hormone alone or with testosterone on body composition and measures of performance .