In the fitness and bodybuilding community, the most profound effect of low testosterone is the negative effects on muscle mass and strength. Research shows that without adequate testosterone levels, the ability of the muscles to synthesize protein is reduced. So, no matter how many protein bars or shakes you take, without enough testosterone, your body cannot synthesize protein at the rate required to increase or even maintain muscle mass.
Exogenous or supplemental testosterone has been shown to have many positive effects on the body that are tempting athletes of all kinds. The most prevalent of these is muscular size and strength. Several studies have demonstrated increase in lean mass in a variety of populations from older men, younger men, bodybuilders, and strength-trained athletes. While it has been noted that the use of Androgenic Anabolic Steroids (AAS) may lead to some water retention contributing to weight gain, the overall consensus is that it is due to lean mass accretion.
The current literature supports the notion that increase in lean mass will increase performance. The most notable of these performance increases were seen in markers of strength. Over two dozen studies have shown AAS to be effective at increasing strength. Others have shown similar findings in just 3-4 weeks of administration. A review of the available literature determined that the strength changes are between 5-20% of baseline strength. With the evolution of scientific research, many testosterone replacement or booster therapies are available today to overcome low testosterone.
Injections of the anabolic hormone testosterone exogenously, at the amount ten times higher than that of the human body, result in negative feedback. The excess amount of testosterone converts to estrogen through the aromatase enzyme. This reaction results in a concomitant increase in estrogen levels in a male body. The high level of estrogen is read by hypothalamus as a danger sight and then, the body shuts down the production of testosterone. It is called as hypothalamic-pituitary-testicular axis (HPTA) shut down.
As the male body does not produce estrogen from any organ (it is produced from the conversion of testosterone), it does not have any way to control the increase or decrease in the production of estrogen in the body. As there is an increase in testosterone, the body needs to handle a higher level of estrogen. Now since the body has already shut down its testosterone production and has a high amount of estrogen, hormonal imbalance can occur. This can result in decreased libido, sexual performance and sperm count, erectile dysfunction, and shrinkage of testicles. When an exogenous testosterone therapy stops, there is an immediate decline in muscle and increase in fat.