TORONTO — The short-term use of either growth hormone or testosterone alone does not significantly improve physical performance among recreational athletes, according to research presented in a poster at the annual meeting of the Endocrine Society.
However, the combination of growth hormone and testosterone did significantly increase sprint capacity in men, the researchers found.
Dr. Ken K.Y. Ho, of the Garvan Institute in Sydney, Australia, and his colleagues conducted a prospective, double-blind placebo-controlled study looking at the effects of growth hormone and testosterone supplementation among 97 recreational athletes from 18–40. The mean age of the study participants was 27 years. The researchers defined a recreational athlete as one who exercised at least 2 hr/wk for at least 1 year.
The study was funded by the World Anti-Doping Agency and the Australian Government Anti-Doping Research Program. The supplements were provided by Novo Nordisk and Organon.
Sixty-four men were randomized to receive either placebo, growth hormone (Norditropin), testosterone (Sustanon), or a combination of growth hormone and testosterone over the 8-week study period. In addition, 33 women were randomized to receive either placebo or growth hormone.
Study participants in the growth hormone or combination arms received up to 2 mg/day of growth hormone for 8 weeks. Men in the testosterone or combination arms received 250 mg/wk of testosterone for 5 weeks. The researchers assessed endurance, strength, power, and sprint capacity using a variety of physical tests.
They found that there was no significant change from baseline among any group in terms of endurance, strength, or power. The only significant finding was among men who took a combination of growth hormone and testosterone. In that group, there was a statistically significant increase in sprint capacity, as measured via a 30-second cycle Wingate test that measured total work and peak power.