Trenbolone is similar to the highly popular steroid Nandrolone, in that they are both 19-nor steroids, meaning that a testosterone molecule has been altered at the 19th position to give us a new compound. Unlike Nandrolone however Trenbolone is an excellent mass and hardening drug with the majority of gains being muscle fiber, with minimal water retention (1) It has an unbelievable anabolic (muscle building) score of 500. When you compare that to Testosterone, which itself is a powerful mass builder, and has an anabolic score of 100 you can begin to fathom the muscle building potential of Trenbolone. What makes Trenbolone so anabolic? Numerous factors come into play. Trenbolone greatly increases the level of the extremely anabolic hormone IGF-1 within muscle tissue (2). And, its worth noting that not only does it increase the levels of IGF-1 in muscle over two fold, it also causes muscle satellite cells (cells that repair damaged muscle) to be more sensitive to IGF-1 and other growth factors(3). The amount of DNA per muscle cell may also be significantly increased