Hau Liu, MD, MBA, MPH; Dena M. Bravata, MD, MS; Ingram Olkin, PhD; Anne Friedlander, PhD; Vincent Liu, MD; Brian Roberts, MD; Eran Bendavid, MD, MPH; Olga Saynina, MA, MBA; Shelley R. Salpeter, MD; Alan M. Garber, MD, PhD; Andrew R. Hoffman, MD
Acknowledgment: The authors thank Rikke Ogawa, MLIS, and Christopher Stave, MLS, Information Services Librarians, Lane Medical Library, Stanford University, for their assistance with the literature searches. They also thank Arthur Weltman, PhD, University of Virginia, for his insight and expertise in growth hormone and exercise physiology. Ms. Ogawa, Mr. Stave, and Dr. Weltman did not receive compensation for their contributions.
Grant Support: In part or fully by the Agency for Healthcare Research and Quality (National Research Service Award, grant no. HS000028-19), the U.S. Department of Veteran Affairs, Stanford University Medical Center, Stanford University, Genentech (fellowship stipend), the National Science Foundation, and the Evidence-Based Medicine Center of Excellence of Pfizer.
Potential Financial Conflicts of Interest:Consultancies: A.M. Garber (Blue Cross and Blue Shield Association), A.R. Hoffman (Genentech, Teva, LG Life Sciences, Ambrx). Honoraria: A.R. Hoffman (Genentech). Stock ownership or options (other than mutual funds): A.R. Hoffman (Ambrx). Expert testimony: A.R. Hoffman (U.S. Attorney, regarding off-label growth hormone use). Grants received: A.R. Hoffman (Genentech, Pfizer).
Requests for Single Reprints: Hau Liu, MD, MBA, MPH, Santa Clara Valley Medical Center, 751 South Bascom Avenue, 4th Floor Medicine, San Jose, CA 95128; e-mail, email@example.com.
Current Author Addresses: Drs. H. Liu and Salpeter: Santa Clara Valley Medical Center, 751 South Bascom Avenue, San Jose, CA 95128.
Drs. Bravata, Bendavid, and Garber and Ms. Saynina: 117 Encina Commons, Stanford, CA 94305.
Dr. Olkin: Department of Statistics, Stanford University, Sequoia Hall, 390 Serra Mall, Stanford, CA 94305.
Dr. Friedlander: Stanford Center on Longevity, Encina Hall, East Wing–5th Floor, 616 Serra Street, Stanford, CA 94305.
Dr. V. Liu: Division of Pulmonary and Critical Care Medicine, Stanford University, 300 Pasteur Drive, Room H3143, Stanford, CA 94305.
Drs. Roberts and Hoffman: Division of Endocrinology and Metabolism, Stanford University, 300 Pasteur Drive, Stanford, CA 94305.
Human growth hormone is reportedly used to enhance athletic performance, although its safety and efficacy for this purpose are poorly understood.
To evaluate evidence about the effects of growth hormone on athletic performance in physically fit, young individuals.
MEDLINE, EMBASE, SPORTDiscus, and Cochrane Collaboration databases were searched for English-language studies published between January 1966 and October 2007.
Randomized, controlled trials that compared growth hormone treatment with no growth hormone treatment in community-dwelling healthy participants between 13 and 45 years of age.
2 authors independently reviewed articles and abstracted data.
44 articles describing 27 study samples met inclusion criteria; 303 participants received growth hormone, representing 13.3 person-years of treatment. Participants were young (mean age, 27 years [SD, 3]), lean (mean body mass index, 24 kg/m2 [SD, 2]), and physically fit (mean maximum oxygen uptake, 51 mL/kg of body weight per minute [SD, 8]). Growth hormone dosage (mean, 36 µg/kg per day [SD, 21]) and treatment duration (mean, 20 days [SD, 18] for studies giving growth hormone for >1 day) varied. Lean body mass increased in growth hormone recipients compared with participants who did not receive growth hormone (increase, 2.1 kg [95% CI, 1.3 to 2.9 kg]), but strength and exercise capacity did not seem to improve. Lactate levels during exercise were statistically significantly higher in 2 of 3 studies that evaluated this outcome. Growth hormone–treated participants more frequently experienced soft tissue edema and fatigue than did those not treated with growth hormone.
Few studies evaluated athletic performance. Growth hormone protocols in the studies may not reflect real-world doses and regimens.
Claims that growth hormone enhances physical performance are not supported by the scientific literature. Although the limited available evidence suggests that growth hormone increases lean body mass, it may not improve strength; in addition, it may worsen exercise capacity and increase adverse events. More research is needed to conclusively determine the effects of growth hormone on athletic performance.
Appendix Table 1. Search Strategy
Study flow diagram.
GH = growth hormone. *Sum may be greater than total number excluded because some studies had multiple reasons for exclusion.
Table 1. Baseline Characteristics of Participants and Study Intervention
Table 2. Study Quality
Appendix Table 2. Key Outcomes Available for Analysis
Table 3. Summary Effect Sizes for Body Composition, Strength, and Basal Metabolism
Effect of growth hormone (GH) on body composition.
We used a random-effects model and a weighted mean difference effect size to compare GH-treated and non–GH-treated participants. The black diamond represents the summary effect size for the outcome of interest. Values greater than 0 indicate that results with GH treatment were higher than those without GH treatment. The studies are ordered by mean effect size. *Male. †Female. ‡High-dose group. §Low-dose group.
Effect of growth hormone (GH) on strength.
We used a random-effects model and a weighted mean difference effect size to compare GH-treated and non–GH-treated participants. The black diamond represents the summary effect size for the outcome of interest. Values greater than 0 indicate that results with GH treatment were higher than those without GH treatment. The studies are ordered by mean effect size. 1RM = 1 repetition maximum.
Effect of growth hormone (GH) on basal metabolism.
We used a random-effects model and a weighted mean difference effect size to compare GH-treated and non–GH-treated participants. The black diamonds represents the summary effect size for the outcome of interest. Values greater than 0 indicate that results with GH treatment were higher than those without GH treatment. The studies are ordered by mean effect size. RER = respiratory exchange rate; RQ = respiratory quotient. *Low-dose group; data obtained from reference 50. †Low-dose GH. ‡High-dose GH. Data obtained from reference 50. §High-dose GH.
Table 4. Qualitative Summary for Exercise Capacity
Table 5. Key Adverse Events
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Liu H, Bravata DM, Olkin I, Friedlander A, Liu V, Roberts B, et al. Systematic Review: The Effects of Growth Hormone on Athletic Performance. Ann Intern Med. 2008;148:747-758. doi: 10.7326/0003-4819-148-10-200805200-00215
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Published: Ann Intern Med. 2008;148(10):747-758.
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