It's no secret that anabolic steroids (., drugs that mimic testosterone) build muscle mass. However, existing supplements that claim to boost testosterone, like Tribulus Terrestris, D-Aspartic Acid, Eurycoma Longifolia and Fenugreek, have no scientific support proving that they are anabolic agents in young and healthy men. Even if they do boost testosterone slightly, the effect is not great enough in magnitude or duration to cause muscle growth. A much better approach than using alleged testosterone boosters is to train harder, sleep more and eat more high-quality food (and take creatine, protein and HMB).
Testosterone can be administered parenterally , but it has more irregular prolonged absorption time and greater activity in muscle in enanthate , undecanoate , or cypionate ester form. These derivatives are hydrolyzed to release free testosterone at the site of injection; absorption rate (and thus injection schedule) varies among different esters, but medical injections are normally done anywhere between semi-weekly to once every 12 weeks. A more frequent schedule may be desirable in order to maintain a more constant level of hormone in the system.  Injectable steroids are typically administered into the muscle, not into the vein, to avoid sudden changes in the amount of the drug in the bloodstream. In addition, because estered testosterone is dissolved in oil, intravenous injection has the potential to cause a dangerous embolism (clot) in the bloodstream.
“Reg Park’s theory was that first you have to build the mass and then chisel it down to get the quality; you work on your body the way a sculptor would work on a piece of clay or wood or steel. You rough it out””the more carefully, the more thoroughly, the better”” then you start to cut and define. You work it down gradually until it’s ready to be rubbed and polished. And that’s when you really know about the foundation. Then all the faults of poor early training stand out as hopeless, almost irreparable flaws. [..]