Udo Meinhardt, MD; Anne E. Nelson, PhD; Jennifer L. Hansen, RN; Vita Birzniece, MD, PhD; David Clifford, PhD; Kin-Chuen Leung, PhD; Kenneth Graham, BSc; Ken K.Y. Ho, MD
Note: Drs. Meinhardt and Nelson contributed equally to this article.
Acknowledgment: The authors thank Professor Robert Baxter, Professor David Handlesman, and Dr. Ray Kazlauskas for their contribution to the larger project that this study was part of. They also thank Dr. Glenn Stone for statistical advice; Sue Min Choong and Amie Lau for technical support; Irene Walker and Angela Peris for clinical assistance; all the volunteers for their participation; and the University of New South Wales (UniGym, Sports Association, and the Faculties of Sports Science and Medicine), University of Sydney (Sydney University Sport and the Faculty of Medicine), and the Australian College of Physical Education for assistance with recruitment.
Grant Support: By the World Anti-Doping Agency, Australian Government (through the Anti-Doping Research Program of the Department of Communications, Information Technology, and the Arts), and the Swiss National Foundation and the Federal Council of Sports (Dr. Meinhardt). Novo Nordisk and Organon provided the study medication.
Potential Conflicts of Interest: Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M09-0826.
Reproducible Research Statement:Study protocol and data set: Not available. Statistical code: Available from Dr. Ho (K.email@example.com).
Requests for Single Reprints: Ken K.Y. Ho, MD, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, New South Wales 2010, Sydney, Australia; e-mail, firstname.lastname@example.org.
Current Author Addresses: Dr. Meinhardt: Centre for Pediatric Endocrinology, Moerlistrasse 69, CH 8006 Zurich, Switzerland.
Drs. Nelson, Birzniece, and Ho and Ms. Hansen: Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, New South Wales 2010, Sydney, Australia.
Dr. Clifford: CSIRO Mathematical and Information Sciences, North Ryde, New South Wales 1670, Sydney, Australia.
Dr Leung: Department of Infectious Diseases and Microbiology, The Children's Hospital at Westmead, New South Wales 2145, Westmead, Australia.
Mr. Graham: New South Wales Institute of Sports, Olympic Park, New South Wales 2127, Sydney, Australia.
Author Contributions: Conception and design: U. Meinhardt, A.E. Nelson, K.C. Leung, K. Graham, K.K.Y. Ho.
Analysis and interpretation of the data: U. Meinhardt, A.E. Nelson, J.L. Hansen, V. Birzniece, D. Clifford, K.C. Leung, K. Graham, K.K.Y. Ho.
Drafting of the article: U. Meinhardt, A.E. Nelson, J.L. Hansen, V. Birzniece, K.C. Leung, K. Graham, K.K.Y. Ho.
Critical revision of the article for important intellectual content: U. Meinhardt, A.E. Nelson, V. Birzniece, K.C. Leung, K. Graham, K.K.Y. Ho.
Final approval of the article: U. Meinhardt, A.E. Nelson, V. Birzniece, D. Clifford, K.C. Leung, K. Graham, K.K.Y. Ho.
Provision of study materials or patients: U. Meinhardt, K. Graham.
Statistical expertise: D. Clifford, K.K.Y. Ho.
Obtaining of funding: A.E. Nelson, K.C. Leung, K.K.Y. Ho.
Administrative, technical, or logistic support: U. Meinhardt, A.E. Nelson, K.K.Y. Ho.
Collection and assembly of data: U. Meinhardt, A.E. Nelson, J.L. Hansen, V. Birzniece.
Meinhardt U, Nelson AE, Hansen JL, Birzniece V, Clifford D, Leung K, et al. The Effects of Growth Hormone on Body Composition and Physical Performance in Recreational Athletes: A Randomized Trial. Ann Intern Med. 2010;152:568-577. doi: 10.7326/0003-4819-152-9-201005040-00007
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Published: Ann Intern Med. 2010;152(9):568-577.
Growth hormone is widely abused by athletes, frequently with androgenic steroids. Its effects on performance are unclear.
To determine the effect of growth hormone alone or with testosterone on body composition and measures of performance.
Randomized, placebo-controlled, blinded study of 8 weeks of treatment followed by a 6-week washout period. Randomization was computer-generated with concealed allocation. (Australianâ€“New Zealand Clinical Trials Registry registration number: ACTRN012605000508673)
Clinical research facility in Sydney, Australia.
96 recreationally trained athletes (63 men and 33 women) with a mean age of 27.9 years (SD, 5.7).
Men were randomly assigned to receive placebo, growth hormone (2 mg/d subcutaneously), testosterone (250 mg/wk intramuscularly), or combined treatments. Women were randomly assigned to receive either placebo or growth hormone (2 mg/d).
Body composition variables (fat mass, lean body mass, extracellular water mass, and body cell mass) and physical performance variables (endurance [maximum oxygen consumption], strength [dead lift], power [jump height], and sprint capacity [Wingate value]).
Body cell mass was correlated with all measures of performance at baseline. Growth hormone significantly reduced fat mass, increased lean body mass through an increase in extracellular water, and increased body cell mass in men when coadministered with testosterone. Growth hormone significantly increased sprint capacity, by 0.71 kJ (95% CI, 0.1 to 1.3 kJ; relative increase, 3.9% [CI, 0.0% to 7.7%]) in men and women combined and by 1.7 kJ (CI, 0.5 to 3.0 kJ; relative increase, 8.3% [CI, 3.0% to 13.6%]) when coadministered with testosterone to men; other performance measures did not significantly change. The increase in sprint capacity was not maintained 6 weeks after discontinuation of the drug.
Growth hormone dosage may have been lower than that used covertly by competitive athletes. The athletic significance of the observed improvements in sprint capacity is unclear, and the study was too small to draw conclusions about safety.
Growth hormone supplementation influenced body composition and increased sprint capacity when administered alone and in combination with testosterone.
The World Anti-Doping Agency.
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