Body composition response to exogenous GH during training in highly conditioned adults

Area of Science:

• Exercise Physiology
• Endocrinology
• Sports Science

Background:

• Growth hormone (GH) plays a crucial role in metabolism and body composition.
• Understanding the effects of exogenous GH administration is important for athletes and clinicians.
• Biosynthetic methionyl-human growth hormone (met-hGH) is a synthetic form of GH.

Purpose of the Study:

• To investigate the impact of met-hGH on body composition in well-trained exercising adults.
• To assess the effects of met-hGH on endogenous growth hormone (GH) and insulin-like growth factor I (IGF-I) secretion.
• To determine the relationship between met-hGH dosage and changes in body composition.

Main Methods:

• Double-blind, repeated-measures design with counterbalanced treatment order.
• Eight well-trained adults received either met-hGH (2.67 mg/day, 3 days/wk) or placebo for 6 weeks.
• Body composition was assessed using hydrodensitometry; GH and IGF-I levels were measured via stimulation tests and blood sampling.

Main Results:

• met-hGH significantly decreased body fat percentage (%fat) and increased fat-free weight (FFW) and FFW/fat weight (FW) ratio.
• Placebo treatment did not yield significant changes in body composition measures.
• Elevated mean IGF-I levels and suppressed GH response to stimulation were observed with met-hGH treatment.
• Changes in FFW/FW correlated with met-hGH dosage, independent of IGF-I levels or GH response.

Conclusions:

• Supraphysiological doses of met-hGH can alter body composition in exercising adults in a dose-dependent manner.
• met-hGH administration may suppress endogenous GH release in some individuals.
• These findings highlight the potential for exogenous GH to impact body composition and endocrine function in trained individuals.