http://tracking.si.com/2013/01/30/alabama-players-swats-deer-antler-spray-college-football/
Just what exactly is IGF-1?
Dr. Spyros Mezitis, an endocrinologist at Lenox Hill Hospital in New York City, explained to CBSNews.com that IGF-1 is an insulin-like growth factor, a hormone that naturally occurs in the body and circulates in the blood. A person's endocrine system contains a pituitary gland that produces a chemical called growth hormone that helps children grow into adults by making their bones stronger and helping their bodies mature. The brain's growth hormone then stimulates the liver to produce IGF-1, which then binds to receptors in muscle cells, signalling them to multiply and grow.
In normal ranges, IGF-1 in the body aids growth and boosts muscle strength, he said. The hormone also increases metabolism of carbohydrates, bringing more sugars to the cells that also help muscle growth.
Some people with medical conditions in which they have low growth hormone, such as dwarfism, can be treated with injections of IGF-1, according to Mezitis.
However, "We do not prescribe [IGF-1 ] on a basis for muscle building," Mezitis, who does not treat athletes, said. He added that he was aware of a spray, but notes it is not as potent as the injection. If IGF-1 is abused, he said, people may experience more muscle strength and issues with aggressiveness.
Athletes who take growth hormone in the form of HGH -- another substance banned by the league, but not currently measured in NFL drug tests -- may also experience more muscle growth.
IGF-1 is "just like giving someone human growth hormone," Don Catlin, the former head of UCLA's Olympic Analytical Lab, told
The New York Times. "It goes to the same kinds of receptors and turns them on."