3. Duration of use is an extremely very influential factor but very easily understood, as it need not be explained that the longer a particular anabolic steroid cycle is run, the increased incidence of side effects will also present themselves as the duration of use becomes longer and longer. The recovery of natural endogenous Testosterone production also becomes increasingly difficult following the termination of an anabolic steroid cycle if a cycle is run for longer and longer lengths of time. Various anabolic steroids may exhibit higher degrees of HPTA suppression and shut-down than other compounds, but all anabolic steroids exhibit this effect of HPTA suppression and eventual shutdown as duration of use continues. Severely atrophied Leydig cells in the testes following extremely long cycles will have far greater difficulty re-engaging endogenous Testosterone production again due to desensitization to gonadotropins resultant of long-term suppression/shutdown. Ideal cycle lengths for short-estered anabolic steroids should be in the range of 8 – 10 weeks, and for long-estered anabolic steroids, 10 – 12 weeks. Any longer than this and the individual runs high risk of increasingly difficult HPTA recovery.