Testosterone can maintain muscle strength and mass, maintain bone density and strength, and improve energy.  Testosterone affects many body systems and functions, including blood production, calcium balance, bone mineralization, lipid metabolism, glucose metabolism, and prostate growth.  It is the main male sex hormone and anabolic hormone.  For both men and women, it has important health effects, including increased libido, strength, immune function, and anti-osteoporosis effects.  Adult males are estimated to produce 20 times more testosterone than adult females.  Testosterone is also an important reason for boys to be active, competitive, adventurous and eager to be the strongest, bravest and strongest man, and plays a crucial role in boys' growth and development.