General description

YK-11 is a synthetic steroidal selective androgen receptor modulator (SARM). SARMs are very similar to steroids because they increase muscle growth (improving lean body mass, LBM) and can help with fat loss, but they were designed in the hopes of having less severe side effects than steroids while also preventing the possibility of addiction. It is labeled as the most potent myostatin inhibitor on the market [1,2], was first studied in 2011 by the Japanese researcher Yuihi Kanno. YK11 attaches to the androgen receptor to help inhibit the production of myostatin in the muscle, easing the muscle to create more FST, thus, increasing muscle growth [1,2].

Selective androgen receptor modulators (SARMs) are small-molecule drugs that can exert varying degrees of both agonist and antagonist effects on ARs (Androgen receptors) in different tissues. Their actions can be understood by considering the selective estrogen receptor modulators (SERMs) that preceded them [3]. One SERM widely used to treat breast cancer, tamoxifen, acts as an antagonist in the breast, an agonist in the bone, and a partial agonist in the uterus. The tissue-specific effects of these agents are precisely what makes them attractive, because they can be tailored to address specific medical conditions while minimizing off-target effects [3].

Health Benefits

Increased Muscle Mass 

YK11 has an incredible ability to increase your lean muscle mass. Out of every other SARM on the market right now, YK11 will result in the biggest muscle gain during a cycle. The reason YK11 helps build muscle so well is that it blocks Myostatin (a protein that reduces muscle) and shoots up Follistatin levels (Follistatin promotes muscle gain). This results in an incredible ability to increase lean body mass when bulking and preserve your muscle when cutting [4].

Strengthened Bones

With the research we have right now, we have seen that YK11 shoots up the amount of activated PKB (Protein Kinase B) in the body. PKB is responsible for the growth of bone cells. This means that YK11 supports bone health and reduces bone breakability [4].

Increased Strength

People who take YK11 report incredible strength gains along with the muscle gains. They are able to consistently get stronger week after week and break their bench press, squat and deadlifts by up to 50 pounds each during a cycle [4].

Molecular mechanism of SARM

The AR is widely distributed in tissues such as skeletal muscle, cardiac and smooth muscles, bone, prostate, sebaceous glands, seminal vesicle, male and female genitalia, liver, skin, and brain [5]. Its structure is composed of an N-terminal domain, a DNA binding domain, and a ligand-binding domain that is activated by testosterone and its powerful metabolite dihydrotestosterone (DHT) via the action of 5α-reductase [6]. In addition, a wide range of endogenous and exogenous hormones, growth factors, and peptides have been shown to bind the AR [5]. For AR activation, the ligand diffuses through the cell membrane and binds to an available receptor located within the cytoplasm. The efficacy of the ligand, in this case SARMs, in the activation process is determined by its binding affinity and its ability to replace the corresponding endogenous hormone (i.e., testosterone) [6]. The AR, in an inactive state, is bound to heat shock proteins (HSPs), such as HSP40, 60, 70, and 90, and, when activated, these HSPs are involved in the folding/unfolding process of proteins and immune response. Subsequently, HSP is uncoupled from AR in the presence of a ligand so that forming the AR-ligand complex that translocates into the nucleus where it binds to the androgen response element (ARE) regulating gene expression [7].

But YK11 is also a Myostatin inhibitor (1,2). Myostatin is a protein that reduces muscle mass in our bodies as well as our strength. Follistatin is the antagonist of Myostatin, it increases our muscle mass and strength. Basically, Follistatin keeps Myostatin in place and promotes muscle growth. Myostatin, on the other hand, blocks muscle growth. YK11 aims to increase our Follistatin levels by inhibiting our Myostatin. Because it inhibits the Myostatin, it’s very effective at keeping our muscle mass because Myostatin can’t promote muscle loss. The results of this are increased levels of Follistatin which very effectively promote great muscle gains.

Administration

Generally speaking, a good YK11 dosage is anywhere from 5 to 10mg per day for optimal results. A cycle can last anywhere from 4 to 8 weeks, depending on your goals. And quite frankly, that is all you need. If you’re going to take more than 10mg, you might end up with some side effects. It’s better to take it easy at 5-10mg per day and make significant progress without any issues [8].

Side effects [8]

People who took YK11 and stuck to the recommended report incredible muscle and strength gain and very little side effects. Some people still report side effects such as:

Hair-loss (Most people who report this got their “l(fā)ost” hair back in a few weeks after the cycle, suggesting that the reason hair-loss / hair shedding occurred in the first place was due to them being nervous and stressed during the cycle.). Mild acne (Most people lose acne after the cycle, suggesting that the reason they got it was due to the stress.). Increased aggression; Lower libido (This is due to the testosterone suppression that YK11 causes. Libido will return to normal a few weeks after the cycle); Gyno (This is very, very rare and only happens to people who take dosages close to 40mg a day and keep their cycle up for over 12 weeks.)

It is also worth noting that YK11 does not cause liver damage up to a 30mg dosage. After that, the substance can become toxic to the body and make unnecessary damage to the liver or other organs.

Reference

1. Yuichiro Kanno, et al., Selective androgen receptor modulator, YK11, regulates myogenic differentiation of C2C12 myoblasts by follistatin expression, Biol. Pharm. Bull. 36 (2013) 1460e1465.

2. Su J, Ag B, Jes A, et al. Myostatin inhibitor YK11 as a preventative health supplement for bacterial sepsis[J]. Biochemical and Biophysical Research Communications, 2021, 543:1-7.

3. Zachary J, Solomon, Rivera J, et al. Selective Androgen Receptor Modulators: Current Knowledge and Clinical Applications [J]. Sexual medicine reviews, 2019.

4. https://sarmguide.com/yk11/

5. Negro-Vilar A. Selective androgen receptor modulators (SARMs): a novel approach to androgen therapy for the new millennium. J Clin Endocrinol Metab. 1999;84:3459-3462.

6. Azhagiya Singam ER, Tachachartvanich P, La Merrill MA, et al. Structural Dynamics of Agonist and Antagonist Binding to the Androgen Receptor. J Phys Chem B. 2019;123:7657-7666.

7. Heemers HV, Tindall DJ. Androgen receptor (AR) coregulators: a diversity of functions converging on and regulating the AR transcriptional complex. Endocr Rev. 2007;28:778-808.

8. https://www.peptidesecrets.com/yk-11/