As we all know, Testosterone was the first steroid to be synthesized. Now, it remains the gold standard of all steroids. First, we?ll discuss Testosterone in general, and in depth, then we?ll examine exactly how (and what) the propionate ester is (together, testosterone propionate is often referred to as just “prop” or “test prop”). Testosterones anabolic/androgenic ratio is 1:1 meaning it is exactly as anabolic as it is androgenic. Actually, testosterone is the steroid which all anabolic/androgenic ratio?s are based on. If a steroid is 2:1, then it is, compared with testosterone?s ratio, doubly as anabolic as it is androgenic. Hence, we see from testosterone?s ratio, it is both quite anabolic as well as androgenic. So how exactly does Testosterone build muscle? Well, Testosterone promotes nitrogen retention in the muscle (6), and the more nitrogen the muscles holds the more protein the muscle stores, and the bigger the muscle gets. Testosterone can also increase the levels of another anabolic hormone, IGF-1, in muscle tissue (7). IGF-1 is, alone, highly Testosterone Propionate anabolic and can promote muscle growth. It is responsible for much of the anabolic activity of Growth Hormone (GH). IGF-1 is also one of the few hormones positively correlated with both muscle cell hyperplasia and hyperphasia (this means it both creates more muscle fibers as well as bigger fibers). All of this leads me to speculate that for pure mass, IGF-1, GH, and Testosterone would be a very effective combination. Testosterone also has the amazing ability to increase the activity of satellite cells(8). These cells play a very active role in repairing damaged muscle. Testosterone also binds to the androgen receptor (A.R.) to promote all of the A.R dependant mechanisms for muscle gain and fat loss (9), but clearly, as we?ve seen, this isn?t the only mechanism by which it promotes growth.