The Human Growth Hormone, which many athletes in the United States and elsewhere use, most of the time illegally, brings no real benefit. Even though it is known that the HGH increases muscle mass, it does not improve performance and in some cases it can lower it, a new study found. Furthermore, intake of Human Growth Hormone may increase fatigue and the risk of injury. The muscle mass is increased by retaining more fluid, but they are not stronger.

"What we saw is that while there was a change in body composition, we didn't find evidence that growth hormone improves athletic performance," Dr. Hau Liu of Stanford University in California, who led the study, told Reuters.

The Human Growth Hormone is banned in the United States for enhancing sports performance. It is also banned by the International Olympic Committee, Major League Baseball and the National Football League.

"The key takeaway is that we don't have any good scientific evidence that growth hormone improves athletic performance," Dr. Andrew Hoffman, a professor of endocrinology, gerontology and metabolism, told Reuters.

However, the scientists reminded that athletes take far higher doses of the HGH and they combine it with other hormones, mainly testosterone, which indeed makes muscles stronger. The increased performance from the intake of some hormones has also severe consequences. Some rap and hip-hop stars also take hormones to look "better".

HGH is a 191-amino acid, single chain polypeptide hormone which is secreted by the omatotroph cells within the anterior pituitary gland. It is released normally as several large pulses or peaks each day.