Growth hormone treatment resulted in quicker, leaner athletes

Researchers in Australia have published data showing a positive effect of human growth hormone treatment on sprint capabilities in athletes. The effect was even more pronounced when testosterone was co-administered.

Athletes taking human GH experienced a 0.4-second improvement in a 10-second sprint.

“This improvement could turn the last place finished in the Olympic finals into a gold medal winner,” Ken Ho, MD, head of the department of endocrinology at St. Vincent’s Hospital in Sydney, said in a press release.

These data justify GH being a banned substance, even though evidence of its performance-enhancing effect has been poor until now, according to the researchers.

The study included 96 recreationally trained athletes, including 63 men (mean age, 28 years). Ho and colleagues randomly assigned athletes to placebo, GH 2 mg per day, testosterone 250 mg per week for men only, or combined GH and testosterone.

Spring capacity significant improvement for men and women who received human GH (combined improvement, 0.71 kJ; 95% CI, 0.1-1.3), for a relative increase of 3.9%.

Men assigned to GH and testosterone experienced greater improvements in sprint capacity (0.71 kJ; 95% CI, 0.5-3.0), equal to a relative increase of 8.3%.

In a six-week follow-up, spring capacity improvements were not maintained, according to the researchers.

Combination treatment in men was also associated with significantly reduced fat mass and increased lean body mass through an increase in extracellular water and body cell mass.

The researchers noted no significant changes in other performance measures such as endurance, strength and power.

Athletes in all treatment groups reported swelling, joint/muscle pain, paresthesias and acne; however, adverse effects were more frequent in those assigned to GH, particularly joint pain.

“In our study, we used doses of GH on the low end of what is believed to be abused in sports,” Ho said. “For that reason, we think that the real effects of GH could be far greater than what is reported in our study. Equally, the side effects could be much more serious, as well.”

The researchers suggested future research to address aerobic performance, strength and power responses to GH treatment at higher doses for longer periods and an examination of the biochemical mechanisms that trigger GH’s improvement of anaerobic capacity.

Meinhardt and colleagues have shown alterations in physical performance when healthy recreational athletes of both genders were administered rhGH for eight weeks in doses about fivefold the replacement dose (for adults with GH deficiency), followed by a washout period. These doses are likely at the lower end of amounts abused by more accomplished athletes. It was previously known that rhGH could alter body composition with an approximately equal decrement in fat mass and increment in lean body mass.
In this study are reported findings from pre-specified primary analysis of secondary outcome data performed to assess how rhGH changes body composition and physical performance. Additionally, in men, the effects of testosterone and combined testosterone and rhGH were evaluated. The main new data indicate a statistically significant increase in sprint capacity (a standard measure of anaerobic power) which may translate to shorter time to complete sprint races. With this dose and duration of administration no other fitness parameters changed — VO2_max, dead lift and jump height — all standard measures in sports physiology. In men co-administered testosterone and rhGH the effects were mainly additive. These findings are in accord with changes noted in children with the Prader-Willi syndrome, given that they have high fat mass and low lean body mass which changes favorably with rhGH therapy and whose performance at physical tasks also improves.
What does all of this mean for the more accomplished athletes? First, it does show a rather large effect size (about 4% change) in performance at this single task after only eight weeks of therapy, which is gone after an additional six weeks. At the elite level, the difference of 0.5% in a sprint may be the difference between an Olympic medal and not making the finals. Second, elite athletes are likely to take greater amounts for longer periods along with much more rigorous training schedules. All may affect their responses to rhGH and whatever other ergogenic aids that they are taking.
In summary, this is the first study to 'validate' what athletes (and the World Anti-Doping Agency) have known for years: that rhGH is anabolic and performance enhancing. This justifies its inclusion of the banner drug list.

– Alan D. Rogol, MD, PhD

Department of Pediatrics, Division of Endocrinology/Diabetes,
University of Virginia Health System

Meinhardt U. Ann Intern Med. 2010;152:568-577.