Testosterone cypionate is an injectable oil which contains testosterone with the cypionate ester attached to the testosterone molecule. The ester denotes the release pattern of the test after it is injected into the body. This particular ester gives the testosterone an active life of 15-16 days, although blood levels of this drug fall sharply five days post-administration, testosterone levels are still above baseline after a week. Stable blood levels can be achieved with once per week injections. Our clients often administer the drug twice weekly or every three to five days. Many people believe that testosterone cypionate is more or less powerful than the other popular injectable testosterone enanthate. The truth is, they are almost identical in release patterns, so there is virtually no difference between the two.
Testosterone is significantly correlated with aggression and competitive behaviour and is directly facilitated by the latter. There are two theories on the role of testosterone in aggression and competition.  The first one is the challenge hypothesis which states that testosterone would increase during puberty thus facilitating reproductive and competitive behaviour which would include aggression.  Thus it is the challenge of competition among males of the species that facilitates aggression and violence.  Studies conducted have found direct correlation between testosterone and dominance especially among the most violent criminals in prison who had the highest testosterone levels.  The same research also found fathers (those outside competitive environments) had the lowest testosterone levels compared to other males.