Androgens are derivatives of cyclopentano-perhydrophenanthrene. Endogenous androgens are C-19 steroids with a side chain at C-17, and with two angular methyl groups. Testosterone is the primary endogenous androgen.

Testosterone Enanthate, owing to its highly anabolic/highly androgenic effects, tends to be used in an off-season mass cycle. Water retention during administration of testosterone with this particular ester is reasonably high.

Testosterone suppresses HPTA function quickly and severely. HCG and nolvadex  are considered after a cycle  to stimulate normal endogenous (natural) testosterone production within a rapid period of time at the point of post use. Males have typically injected 400-1000mg weekly, in conjunction with a high anabolic rated drug such as deca-durabolin or Equipoise.  Trenbolone Enanthate is also a popular addition for leaner mass gains