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.
The cited “steroid pump” manifests itself after the intake of oxymetholone in an extreme form and the athlete experiences a corresponding feeling during his training. The high-level androgenic effect of oxymetholone stimulates the regeneration of the body so that it is unlikely to override. The athlete often has the feeling that he can start again from the beginning hours after a strenuous workout. The training pauses can be massively reduced. Here dangers await the joints and bones, which are not accustomed to this stress. Joint pain due to excessive weight is not a rarity.
The reason why Anapolon is still used in professional and competitive bodybuilding today is that Anapolon is considered a strong IGF-1 trigger, which means that the intake of anapolone increases IGF-1 production. IGF-1 is a very strong anabolic hormone.