YK11

YK11 is a special case among the SARM-like compounds. Structurally it is a steroid derivative but it behaves like a selective androgen receptor modulator. It has additionally been described in cell models as a myostatin inhibitor, a compound that could loosen the muscle's natural growth brake.

Up front: there are essentially no human data on YK11. Everything available comes from cell culture.

YK11 activates the androgen receptor as a partial agonist. In muscle cells it increased the production of follistatin, an endogenous counterpart to myostatin. Since myostatin brakes muscle growth, more follistatin would theoretically be a lever for more growth.

Important: this is described in C2C12 muscle cells, not in humans. Whether and how strongly it transfers is open.

Oral, often split across two doses.

• Because of the shorter duration of action, it is frequently split.
• With some water, with or without food.
• Cycles are kept short.

The central study (Kanno, 2013) showed that YK11 in C2C12 muscle cells stimulated the production of follistatin and through it promoted myogenic differentiation. The effect could be reversed with a follistatin antibody, which supports the mechanism.

This is a clean preclinical work but it is cell culture. There are no human studies, no human pharmacokinetics and no long-term data. YK11 is clearly experimental.

• The case literature on SARM-like compounds documents liver strain, and for YK11 the window is judged especially narrow.
• As an androgenically active compound, suppression of the body's own axis is to be expected.
• Solid human side-effect data simply do not exist.

• Keep expectations on the floor, everything rests on cell models.
• If at all, very low and short.
• Banned in official competition.
• Keep an eye on liver and blood values.

Store dry, cool and protected from light, out of reach of children. Keep the original container closed and mind the expiry date.