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 .
Acute growth hormone administration causes exaggerated increases in plasma lactate and glycerol during moderate to high intensity bicycling in trained young men.
We studied the acute effects of a single , sc GH dose on exercise performance and metabolism during bicycling . Seven highly trained men [ age , 26 + /- 1 yr ( mean + /- SEM ) ; weight , 77 + /- 3 kg ; maximal oxygen uptake , 65 + /- 1 ml O(2).min(-1).kg(-1 ) ] performed 90 min of bicycling 4 h after receiving 7.5 IU ( 2.5 mg ) GH or placebo in a r and omized , double-blinded , cross-over design trial . A st and ardized pre-exercise meal was given 2 h before exercise . Blood was sample d at rest and during exercise and analyzed for GH , IGF-I , glucose , lactate , insulin , glycerol , and nonesterified fatty acids ( NEFA ) . In the placebo trial , all subjects completed the exercise protocol without any difficulties . In contrast , two subjects were not able to complete the exercise protocol in the GH trial , and one subject barely managed to complete the protocol . In addition , GH administration result ed in exaggerated increases in plasma lactate concentrations during exercise ( P < 0.0001 ) . The combined lipolytic effect of GH and exercise , evidence d by increased plasma glycerol and serum NEFA concentrations , was 3-fold greater than the effect of exercise alone ( P < 0.0001 ) , but this increased substrate availability did not result in increased whole body fat oxidation ( indirect calorimetry ) . Plasma glucose was , on average , 9 % higher during exercise after GH administration compared with placebo ( P < 0.0001 ) . We conclude that a single , relevant GH dose causes exaggerated increases in plasma lactate and glycerol as well as serum NEFA during 90 min of subsequent bicycling at moderate to high intensity . The exaggerated increase in plasma lactate may be associated with substantially decreased exercise performance
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 .