The amount of free testosterone can be altered (increased) by the use of aromatase inhibitors such as TesTo-Rex???. The less testosterone that is synthesized [aromatized] into estrogen, the more total testosterone) or inhibitors of the plasma proteins that bind into testosterone. Manipulating the tendency of a testosterone to exist in an unbound state is an effective way to alter the overall activity and potency of one's overall testosterone levels. Higher levels of testosterone produce an enhanced anti-glucocorticoid effect, which yields an anti-catabolic, or more precisely, anti-proteoolytic, effect on muscle cells. This indirect anabolic effect is the result of testosterone's high affinity for binding with glucocorticoid receptors, thus blocking the normal messenger pathway that triggers protein release from muscle tissue. More free testosterone also likely results in higher concentrations of IGF-1 and IGF-1 receptor sites in skeletal muscle tissue. Correspondingly, lower testosterone also likely yields less IGF-1 production and a corresponding decrease in IGF-1 receptor sites. Lower free testosterone also likely means a weaker immune system.