Testosterone
is the most important male sex hormone agent produced by the gonads. Its
secretion stimulates the distinction of the male reproductive tract in
the embryo, the descent of the testes into the scrotum, the further
development of the reproductive tract and penis during puberty and
maturation of sperm. It is also responsible for the development of
secondary male sex characteristics such as facial hair, enlargement of
the larynx (deep voice) and increase in production of the sebaceous
glands, all of which are associated with masculine features.
Testosterone also plays a role in the development and persistence of
male libido (sexual desire) and sexual behavior.
Testosterone also has other "non sexual" roles: it performs the important function of protein biosynthesis in accelerating muscle build-up, increasing the formation of red blood cells, and accelerating regeneration and recovery time after illness or injury. It stimulates the entire metabolic activity especially in the energy metabolic pathways and burning of body fat.
As Age Goes Up, Testosterone Levels Go Down
If you ask any elderly man about his levels of endurance and sexual desire, his response will probably be one of dissatisfaction. What causes declining sexual prowess? Aging is a significant factor. But how is aging responsible for this syndrome? The key is declining testosterone levels. Research shows that during puberty, testosterone levels are peaking. Levels reach their lifetime summit at the age of 25, and steadily decrease with age. Some clinical studies indicate that on average testosterone levels drop as much as 2% per year after the age of thirty. Lifestyle habits are a significant factor in the rate of decline. Individuals who exercise regularly have a much slower rate of decline. This is due to the fact that exercise stimulates hormone secretion. A more prominent decline was observed in individuals who are heavy smokers and ingest a lot of alcohol.