Testosterone Propionate is the shortest estered testosterone preparation available on the market currently. It does everything you’d expect from testosterone, but anecdotally seems to promote less water retention than longer estered versions of the product.

This is an esterified form of the base steroid steroid testosterone, much like enanthate, cypionate and sustanon. It's a superlipophillic, oil-based injectable that slows the release of the steroid into the blood stream. But compared to enanthate and cypionate, propionate is a very short ester and is still released quite fast. As such more frequent injections are needed. Levels will peak after 24-36 hours and begin tapering from there on out, making the longest possible time-span between injections, at least or proper results, about 3 days.

Testosterone promotes nitrogen retention in the muscle, 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. IGF-1 is, alone, highly 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).