Effects of High-Dose Growth Hormone on Glucose and Glycerol Metabolism at Rest and During Exercise in Endurance-Trained Athletes

J Clin Endocrinol Metab. 2006 Jan;91(1):320-7. doi: 10.1210/jc.2005-0916. Epub 2005 Nov 1.

Abstract

Context: Recombinant human-GH (r-hGH), in supraphysiological doses, is self-administered by athletes in the belief that it is performance enhancing.

Objective: The objective of this study was to determine whether r-hGH alters whole-body glucose and glycerol metabolism in endurance-trained athletes at rest and during and after exercise.

Design: This was a 4-wk double-blind placebo-controlled trial.

Setting: This study was conducted at St. Thomas Hospital (London, UK).

Participants: Twelve endurance-trained male athletes were recruited and randomized to r-hGH (0.2 U/kg.d) (n = 6) or identical placebo (n = 6) for 4 wk. One (placebo group) withdrew after randomization.

Intervention: Intervention was conducted by randomization to r-hGH (0.2 U/kg x d) or identical placebo for 4 wk.

Main outcome measures: Whole-body rates of appearance (Ra) of glucose and glycerol (an index of lipolysis) and rate of disappearance of glucose were measured using infusions of d-[6-6-2H2]glucose and 2H5-glycerol.

Results: Plasma levels of glycerol and free fatty acids and glycerol Ra at rest and during and after exercise increased during r-hGH treatment (P < 0.05 vs. placebo). Glucose Ra and glucose rate of disappearance were greater after exercise during r-hGH treatment (P < 0.05 vs. placebo). Resting energy expenditure and fat oxidation were greater under resting conditions during r-hGH treatment (P < 0.05 vs. placebo).

Conclusions: r-hGH in endurance-trained athletes increased lipolysis and fatty acid availability at rest and during and after exercise. r-hGH increased glucose production and uptake rates after exercise. The relevance of these effects for athletic performance is not known.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Blood Glucose / metabolism*
  • Calorimetry, Indirect
  • Cross-Over Studies
  • Dietary Carbohydrates / metabolism
  • Double-Blind Method
  • Energy Metabolism / drug effects
  • Exercise / physiology*
  • Exercise Test
  • Fatty Acids / metabolism
  • Fatty Acids, Nonesterified / blood
  • Glycerol / metabolism*
  • Growth Hormone / pharmacology*
  • Human Growth Hormone / blood
  • Humans
  • Lipolysis / drug effects
  • Male
  • Oxidation-Reduction
  • Physical Endurance / physiology*
  • Physical Fitness / physiology*
  • Rest / physiology*

Substances

  • Blood Glucose
  • Dietary Carbohydrates
  • Fatty Acids
  • Fatty Acids, Nonesterified
  • Human Growth Hormone
  • Growth Hormone
  • Glycerol