YK11 sits at an unusual crossroads in peptide and SARM research. Structurally, it resembles a synthetic steroid more than a traditional selective androgen receptor modulator — yet it behaves like one, and then some. Researchers have grown increasingly interested in YK11 because it appears to do two things simultaneously: activate androgen receptors in muscle tissue and suppress myostatin, the protein that limits how much muscle the body can build. That dual mechanism is what makes it one of the most-discussed compounds in the research community today.
What Is YK11?
YK11 (chemical name: (17α,20E)-17,20-[(1-methoxyethylidene)bis(oxy)]-3-oxo-19-norpregna-4,20-diene-21-carboxylic acid methyl ester) is a steroidal selective androgen receptor modulator (SARM) first synthesized and described by researcher Yuichiro Kanno in 2011. Unlike non-steroidal SARMs such as RAD-140 or LGD-4033, YK11’s structure is derived from dihydrotestosterone (DHT), giving it a steroid-like backbone. This matters because the structural similarity to DHT allows it to bind androgen receptors with high affinity — while its unique side chains appear to trigger a different transcriptional response than testosterone or DHT alone.
The compound is currently classified as a research chemical. It is on the World Anti-Doping Agency (WADA) prohibited list and has been detected in doping control samples from competitive athletes. It is not approved for human use by the FDA or any equivalent regulatory body.
Research Overview
Peer-reviewed research on YK11 remains limited but is growing. The bulk of published data covers its androgen receptor binding profile, myostatin inhibition pathway, and — more recently — its neurochemical effects. Below are key findings from indexed studies.
Androgen receptor binding and muscle signaling: Early cell-based studies demonstrated that YK11 acts as a partial agonist at the androgen receptor, stimulating expression of anabolic-specific genes while activating the Follistatin pathway — a known downstream inhibitor of myostatin. Molecular docking analyses have confirmed high binding affinity with the AR, particularly through hydrogen interactions at the Arg752 residue. (DOI: 10.1016/j.jsbmb.2023.106364)
Hippocampal and neurochemical effects (in vivo): A 2024 study published in Chemico-Biological Interactions examined YK11’s impact on rat hippocampus at anabolic doses. The study found that YK11 demonstrated high brain permeability and influenced neurochemical function, including downregulation of the BDNF/TrkB/CREB signaling pathway, increased pro-inflammatory cytokines (IL-1β, IL-6), and initiation of apoptotic cascades. Importantly, groups combining exercise with YK11 showed partial mitigation of some inflammatory markers. (DOI: 10.1016/j.cbi.2024.110971)
Oxidative stress and mitochondrial function: A companion animal study found that YK11 administration promoted increased oxidative stress and impaired all mitochondrial function markers in the hippocampus. Exercise alone had neuroprotective effects, and the combined EXE+YK11 group showed partial protection — though YK11-induced mitochondrial dysfunction was not fully reversed. (DOI: 10.1016/j.jsbmb.2023.106364)
Anti-doping detection: YK11 has been formally detected in a human doping control sample analyzed by the UCLA Olympic Analytical Laboratory, confirming its use in competitive sports. (DOI: 10.1002/dta.3604)
For ongoing academic research, explore PubMed searches for YK11 androgen receptor and Google Scholar for YK11 SARM myostatin.
Community Discussion
The research community discusses YK11 extensively on r/PEDs and r/sarmssourcetalk, covering cycle length, suppression management, and stacking comparisons with LGD-4033 and RAD-140.
Potential Benefits Studied
- Androgen receptor activation in skeletal muscle: In vitro studies confirm YK11 binds AR with high affinity and stimulates muscle-specific anabolic gene expression.
- Myostatin inhibition via Follistatin upregulation: YK11 appears to trigger Follistatin release, suppressing myostatin — the body’s natural brake on muscle growth.
- Selective tissue targeting: As a SARM, YK11 is theorized to exert more targeted androgen activity compared to anabolic steroids.
- Bone density research: Early cell studies suggest potential effects on bone cell differentiation through androgen receptor pathways.
- Stacking synergy: The research community has explored YK11 with GH secretagogues and other SARMs for compounded anabolic signaling.
Dosage & Administration
All dosage information is derived from animal research and community anecdotal data. No human clinical trials for YK11 have been conducted. YK11 50MG/ML is an injectable solution; administration in research contexts is typically subcutaneous. Reported research doses in community discussion range from 5mg to 15mg daily. Cycle lengths range from 6 to 10 weeks, commonly followed by a post-cycle support protocol.
Where to Find It
YK11 50MG/ML is available for research purposes at combatresearch.is.
Conclusion
YK11 represents one of the most mechanistically interesting compounds in the SARM category. Its dual action on androgen receptors and myostatin inhibition sets it apart from nearly every other compound in this class. For researchers studying androgen receptor biology, myostatin inhibition, or anabolic signaling pathways, YK11 remains a compound of significant interest — and one where rigorous, well-designed protocols matter more than ever.
Disclaimer: This article is for educational and informational purposes only. YK11 is a research chemical not approved for human use by the FDA or any regulatory authority. This content does not constitute medical advice, diagnosis, or treatment recommendations. Always consult a licensed healthcare professional before initiating any research protocol.
