Tren Cycle refers to Trenbolone cycle and it could be Trenbolone acetate or Trenbolone enanthate. Tren happens to be the most powerful steroid that can be used for either bulking or cutting. It's so powerful that beginners are advised to stay away from it. It is only experienced, professional and advanced bodybuilders who have done steroids earlier that should try this steroid since the side effects are likely to be as severe and a Tren Cycle requires utmost caution.