Effect of Growth Hormone Administration on the Mass and Strength of Muscles in Healthy Young Adults: A Systematic Review and Meta-Analysis

Abstract

The growth hormone (GH) is prohibited for use by athletes, while its anabolic effect on muscle tissue is still debated. The review provides a systematic evaluation of the GH effects on the body composition and strength parameters in well-trained healthy young subjects. A meta-analysis of published data from randomized controlled trials (RCTs) was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Pooled results of 11 RCTs showed that GH administration significantly increases the lean body mass (2.72, 95% CI: 2.02; 3.38, p < 0.01), total water content (1.10, 95% CI: 0.54; 1.66, p < 0.01), and extracellular water (1.78, 95% CI: 1.04; 2.52, p < 0.01) and reduces the fat mass (–0.67, 95% CI: –0.93; –0.40, p < 0.01) without changing the muscle protein synthesis rate (0.00, 95% CI: –0.01; 0.02, p = 0.70) and muscle strength (–0.02, 95% CI: –0.05; 0.02, p = 0.36) as compared with placebo. A conclusion was made that GH administration can improve the body composition in healthy young subject by exerting a significant lipolytic effect without causing hypertrophy of muscle fibers. The increase in lean body mass is due to an accumulation of extracellular water.