YK-11

YK-11 is a synthetic steroidal compound commonly classified alongside selective androgen receptor modulators (SARMs). In bodybuilding, it is primarily associated with muscle hypertrophy, strength development and increased lean muscle mass. Unlike conventional nonsteroidal SARMs such as Ostarine or Ligandrol, YK-11 has a steroidal chemical structure and is particularly associated with its potential influence on myostatin-related pathways.

YK-11 activates androgen receptor signalling and is associated with increased expression of Follistatin, a protein that can inhibit myostatin, which normally acts as a regulator of muscle growth. Its intended effects include supporting muscle protein synthesis, promoting muscle development and potentially reducing biological signals that limit muscle hypertrophy. This combination of androgen receptor activity and potential myostatin regulation makes YK-11 distinct from other compounds commonly grouped under SARMs.