{description}While athletes who illegally dope with human growth hormone may look better in their uniforms, they probably do not play any better than their rule-abiding teammates, according to a new review by Hau Liu, MD, MBA, PHD, of Stanford University. Dr. Liu’s review, published in the Annals of Internal Medicine on May 20, 2008, compiled results from 44 randomized, controlled studies on human growth hormone (HGH). All studies included in the review examined only lean, physically fit, young, male adults. HGH, which is naturally produced in the human body, regulates processes such as bone and muscle growth and tissue repair. HGH levels reach their peak during childhood, when growth is at a maximum, and the hormone’s secretion continues until old age, at which time it drops off precipitously.{/description}