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Growth hormone and body composition in athletes
1Department of Pediatrics, University of Vienna, Austria. herwig.frisch@akh-wien.ac.at
Journal of Endocrinological Investigation
|August 12, 1999
Summary
Growth hormone (GH) does not enhance muscle strength or performance in healthy adults or athletes. While it increases lean body mass, this is likely due to fluid retention, not improved muscle protein synthesis.
Area of Science:
- Endocrinology
- Sports Medicine
- Exercise Physiology
Background:
- Growth hormone (GH) exhibits anabolic properties, influencing muscle mass and composition.
- Previous studies show GH increases muscle size in animals and corrects body composition in GH-deficient adults.
- GH hypersecretion in acromegaly increases muscle volume but not strength, prompting interest in GH for athletic enhancement.
Purpose of the Study:
- To investigate the effects of growth hormone (GH) administration on muscle strength and performance in healthy individuals and athletes.
- To determine if GH supplementation enhances muscle adaptations to resistance exercise training.
- To clarify the mechanisms behind GH-induced changes in body composition.
Main Methods:
- Review of existing animal and human studies on GH effects on muscle.
- Analysis of studies involving GH treatment in GH-deficient adults and children.
- Examination of research on GH administration in healthy young/older men and experienced weightlifters/power athletes, often with resistance training protocols.
- Measurement of muscle strength, performance, body composition, protein synthesis, and relevant biomarkers like IGF-I.
Main Results:
- GH treatment corrects body composition in GH-deficient adults, increasing lean mass and strength.
- In healthy individuals and athletes, GH does not enhance muscle strength or performance gains from exercise.
- Observed increases in fat-free mass with GH are attributed to fluid retention or connective tissue, not contractile protein accretion.
- GH administration did not increase skeletal muscle protein incorporation or decrease protein breakdown in weightlifters.
- Power athletes on GH showed no improvement in maximal strength despite doubled IGF-I levels.
Conclusions:
- Growth hormone (GH) does not improve muscle strength or performance in healthy adults or athletes.
- The anabolic effects of GH on muscle mass in healthy individuals are likely due to non-contractile tissue changes, such as fluid retention.
- GH supplementation is unlikely to provide additional benefits for strength or performance in highly trained athletes.