Growth hormones improve sprint times in recreational athletes, but safety is unclear

Growth hormones increased sprint capacity in recreational athletes when used alone and in combination with testosterone, according to the first trial to demonstrate that the hormones do affect athletic performance.

Australian researchers in a blinded study followed 96 recreationally trained athletes (63 men and 33 women) with a mean age of 27.9 years (SD, 5.7). Men received either placebo or a hormone (somatropin, Novo Nordisk) in a dose of 2 mg/d subcutaneously, testosterone (Sustanon, Organon) in a dose of 250 mg/wk intramuscularly, or combined treatments. Women received placebo or hormone (2 mg/d).

After eight weeks, researchers assessed fat mass, lean body mass, extracellular water mass and body cell mass and their correlation to endurance (maximum oxygen consumption), strength (dead lift), power (jump height) and sprint capacity on a bicycle (Wingate value). Results appeared in the May 4 issue of Annals of Internal Medicine. Video of the report is available online.

Growth hormone significantly reduced fat mass, increased lean body mass through an increase in extracellular water, and increased body cell mass in men when combined 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. In men co-administered with testosterone, hormone increased sprint capacity by 1.7 kJ (CI, 0.5 to 3.0 kJ; relative increase, 8.3% [CI, 3.0% to 13.6%]). Endurance, strength and power did not significantly change. The increased sprint capacity was not maintained after a six-week washout period.

The improvement in sprint capacity in men who also received testosterone injections would correlate to a 0.4-second improvement over 10 seconds in a 100-meter dash, according to lead author Ken K. Y. Ho, MD. “This improvement could turn the last-place finisher in the Olympic finals into a gold medal winner,” he said.

Growth hormone dosage may have been lower than that used covertly by competitive athletes, who might see bigger gains but also may experience greater side effects. While the study was too small to draw conclusions about safety, patients in all treatment arms reported swelling, joint and muscle pain, paresthesia and acne.