High Dose Growth Hormone Exerts an Anabolic Effect at Rest and during Exercise in Endurance-Trained Athletes

The anabolic actions of GH in GH-deficient adults and children are well documented. Replacement with GH in such individuals promotes protein synthesis and reduces irreversible loss of protein through oxidation. Although GH is known to be self-administered by athletes, its protein metabolic effects i...

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Bibliographic Details
Published in:The journal of clinical endocrinology and metabolism 2003-11, Vol.88 (11), p.5221-5226
Main Authors: Healy, M. L, Gibney, J, Russell-Jones, D. L, Pentecost, C, Croos, P, Sönksen, P. H, Umpleby, A. M
Format: Article
Language:English
Subjects:
Adult
Biological and medical sciences
Carbon Isotopes
Doping in Sports
Hormones. Endocrine system
Human Growth Hormone - administration & dosage
Human Growth Hormone - adverse effects
Humans
Insulin-Like Growth Factor I - metabolism
Leucine - pharmacokinetics
Male
Medical sciences
Oxygen Consumption - drug effects
Oxygen Consumption - physiology
Pharmacology. Drug treatments
Physical Endurance
Physical Exertion - drug effects
Physical Exertion - physiology
Rest - physiology
Sports
Thyroid Hormones - blood
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Summary:The anabolic actions of GH in GH-deficient adults and children are well documented. Replacement with GH in such individuals promotes protein synthesis and reduces irreversible loss of protein through oxidation. Although GH is known to be self-administered by athletes, its protein metabolic effects in this context are unknown. This study was designed to determine whether 4 wk of high dose recombinant human GH (r-hGH) administration altered whole body leucine kinetics in endurance-trained athletes at rest and during and after 30 min of exercise at 60% of maximal oxygen uptake. Eleven endurance-trained male athletes were studied, six randomized to receive r-hGH (0.067 mg/kg·d), and five to receive placebo. Whole body leucine turnover was measured at rest and during and after exercise, using a 5-h primed constant infusion of 1-[13C]leucine, from which rates of leucine appearance (an index of protein breakdown), leucine oxidation, and nonoxidative leucine disposal (an index of protein synthesis) were estimated. Under resting conditions, r-hGH administration increased rate of leucine appearance and nonoxidative leucine disposal, and reduced leucine oxidation (P < 0.01). This effect was apparent after 1 wk, and was accentuated after 4 wk, of r-hGH administration (P < 0.05). During and after exercise, GH attenuated the exercise-induced increase in leucine oxidation (P < 0.05). There were no changes observed in placebo-treated subjects compared with the baseline study. We conclude that GH administration to endurance-trained male athletes has a net anabolic effect on whole body protein metabolism at rest and during and after exercise.
ISSN:0021-972X
1945-7197
DOI:10.1210/jc.2002-021872