HGH Day is a combination of maca, ornithine, arginine and zinc. Maca is a source of steroidal saponins and vegetable sterols. Sterol skeletons (C27) makes up the fundamental part of steroidal saponins, similar to the building structure of testosterone. Arginine is an amino acid responsible for various biochemical functions within the body, being a precursor of nitrogen oxide (NO) secretion. For instance, NO is instrumental in the dilation of the blood vessels. Zinc contributes to the maintenance of normal testosterone levels in the blood and normal protein synthesis. HGH Day is particularly recommended for professional sportsmen pursuing various sports disciplines, especially strength sports (bodybuilding, powerlifting, combat sports).