YK11 is a synthetic steroidal compound primarily researched for its potential applications in muscle growth and bone density enhancement. It functions as a selective androgen receptor modulator (SARM) and inhibits myostatin, a protein that regulates and limits muscle growth. By selectively activating androgen receptor signaling and suppressing myostatin, it may promote muscle hypertrophy, increase protein synthesis, and improve bone strength. This compound is of interest in sports science and bodybuilding, where it is explored for enhancing physical performance and recovery. Additionally, it is being investigated for therapeutic applications in conditions like muscle wasting diseases and osteoporosis, where muscle and bone health are compromised. However, its use remains experimental, not approved for human consumption, and further research is needed to fully understand its efficacy, safety, and potential side effects.