YK-11 works by inhibiting the protein called myostatin by inducing higher production of its antagonist Follistatin. This makes YK-11 extremely synergistic, and the single best compound to stack with other SARMs and PEDs.
YK-11 is almost always used as a secondary compound in a cycle, with the goal of further enhancing the anabolic effects of anything you stack it with.
What to Stack YK11 With
Synergy is the concept of combining PEDs that work through different muscle-building pathways to create synergy and achieve ridiculous results.
The concept of synergy states that combining regular SARMs together is less optimal than combining SARMs that work via a different mechanism of action. This has been shown to be the case in many of the anecdotal reports I’ve come across of users who combined SARMs of the same sort, like LGD 4033 and RAD 140, and experienced a disproportionate increase in side effects to benefits, compared to just taking one SARM or the other.
Nobody really knows why this happens, but a popular theory is that SARMs fight to bind to the same receptors, and one with a higher binding affinity wins and kicks the other out of the receptor, making it useless.
This is why YK11 is so powerful. Because it builds muscle not only by attaching to androgen receptors, but also inhibiting myostatin. It is the only SARM that should be used in conjunction with another (excluding research chemicals like MK677, or Cardarine and Stenabolic, which also work via different mechanisms).
So what can you combine with YK-11?
- Any single SARM (meaning no more than one)
- GH & IGF-1 secretagogues: MK677, CJC-1295, Ipamorelin
- AAS
- Rev-erbα agonists: SR9009; SR9011
- PPAR agonists: Cardarine; GW0742
Here’s a spreadsheet I created to better illustrate what can and what cannot be taken together, based on the concept of synergy:
Generally, YK 11 can be stacked with any other SARM and, on top of that, with other research chemicals, depending on the goal of the cycle.
For example, a cutting YK 11 stack would consist of
- YK 11 – Myostatin pathway
- Cardarine – PPAR pathway
- S4 or MK2866 – Androgen pathway
A good muscle-bulking YK 11 stack would consist of
- YK 11 – Myostatin pathway
- MK 677 – GH & IGF-1 pathway
- RAD 140 or LGD 4033 – Androgen pathway
YK-11 works best when taken with another SARM, or PED, that builds muscle. Combining it with just a PPAR agonist like Cardarine, that’s mainly used for fat loss and endurance enhancement, would be a waste of its muscle-building potential. Though you could still combine the two + a SARM for advanced cutting cycles.
Stacks & Dosing Protocol
All of the below stacks have in-depth step-by-step, day-by-day instructions including dosing protocols for each compound, ancillary drugs, and more.
As far as YK11 goes, this is the standard recommended dosing protocol you need to know.
- Half-life: Unclear
- Dose: 5-10 mg/day
- Timing and Frequency: 2-3x day
- Cycle Length: 4 - 8 weeks
- PCT: Mandatory
LGD 4033 + YK11
WEEK | LGD 4033 | YK 11 | ENCLOMIPHENE | MK 677 (Optional) |
|---|---|---|---|---|
1 | 5mg/day | 10 mg/day | ||
2 | 5mg/day | 10 mg/day | ||
3 | 5mg/day | 12.5mg/day (if feeling suppressed) | 10 mg/day | |
4 | 5mg/day | 12.5mg/day (if feeling suppressed) | 10 mg/day | |
5 | 10mg/day | 5mg/day | 12.5mg/day | 10 mg/day |
6 | 10mg/day | 5mg/day | 12.5mg/day | 10 mg/day |
7 | 10mg/day | 5mg/day | 12.5mg/day | 10 mg/day |
8 | 10mg/day | 5mg/day | 12.5mg/day | 10 mg/day |
9 | 12.5mg/day | |||
10 | 6.25mg/day |
This is an extremely powerful bulking cycle containing YK 11 and LGD 4033 – one of the “best” bulking SARMs.
If 5 mg/day of LGD 4033 is well tolerated in the first 4 weeks, it can be increased to 10 mg/day for the remainder of the cycle.
The goal of this stack is to build as much muscle as possible. It utilizes LGD 4033 as the main muscle builder, and YK11 as a secondary compound to boost the effectiveness of LGD by inhibiting myostatin. MK677 can also be added to the mix to leverage even more muscle building, better sleep, and improved recovery.
This cycle is highly suppressive and will require you to do a test base of some sort. That can be done with:
- Enclomiphene (SARM + SERM)
- 4-Andro at 150 mg/day – followed by a 4-week PCT
- Testosterone injections (125 – 150 mg/week) – Followed by a 4-week PCT
RAD 140 + YK11
WEEK | RAD 140 | YK 11 | ENCLLOMIPHENE | MK 677 (Optional) |
|---|---|---|---|---|
1 | 15mg/day | 10 mg/day | ||
2 | 15mg/day | 10 mg/day | ||
3 | 15mg/day | 12.5mg/day (if feeling suppressed) | 10 mg/day | |
4 | 15mg/day | 12.5mg/day (if feeling suppressed) | 10 mg/day | |
5 | 20mg/day | 5mg/day | 12.5mg/day | 10 mg/day |
6 | 20mg/day | 5mg/day | 12.5mg/day | 10 mg/day |
7 | 20mg/day | 5mg/day | 12.5mg/day | 10 mg/day |
8 | 20mg/day | 5mg/day | 12.5mg/day | 10 mg/day |
9 | 12.5mg/day | |||
10 | 6.25mg/day |
This stack is a dry version of the previous LGD 4033 + YK11 combination, utilizing RAD 140 instead of LGD.
RAD 140 is exceptionally well at building strength, even better than LGD 4033, but the amount of muscle they build is more or less the same. YK 11 will enhance these effects. This stack is perfect for users that want to remain as lean and shredded as possible while gaining mass.
MK 677 can be added as a GH agent to further add to the cycle, though you may gain a slight amount of water if you’re on a big surplus of calories and eating a boatload of carbs.
This cycle is highly suppressive and will require you to do a test base of some sort. I’ve chosen to deploy Enclomiphene in a SARM+SERM protocol.
MK 2866 + YK11
WEEK | Ostarine | YK 11 | ENCLLOMIPHENE | MK 677 (Optional) |
|---|---|---|---|---|
1 | 15mg/day | 10 mg/day | ||
2 | 15mg/day | 10 mg/day | ||
3 | 15mg/day | 12.5mg/day (if feeling suppressed) | 10 mg/day | |
4 | 15mg/day | 12.5mg/day (if feeling suppressed) | 10 mg/day | |
5 | 25mg/day | 5mg/day | 12.5mg/day | 10 mg/day |
6 | 25mg/day | 5mg/day | 12.5mg/day | 10 mg/day |
7 | 25mg/day | 5mg/day | 12.5mg/day | 10 mg/day |
8 | 25mg/day | 5mg/day | 12.5mg/day | 10 mg/day |
9 | 12.5mg/day | |||
10 | 6.25mg/day |
This stack utilizes Ostarine in conjunction with YK11, and can be used for bulking, cutting, and recomping alike.
But it will be most effective at building muscle on a caloric surplus.
With Ostarine you will gain a modest amount of muscle, but more importantly also joint and connective tissue protection. YK11 is known to cause stiff and dry joints, so combining it with something that has tissue-healing properties makes sense.
If you want to take it one step further, adding MK 677 to the mix would create an even stronger synergy by leveraging the GH and IGF-1 pathway. It will also lubricate your joints by retaining a bit of water.
You’ll get better recovery, sleep, and build more muscle.
In terms of suppression, this stack should be treated as a highly suppressive cycle, even though it utilizes Ostarine.
A test base will be necessary if you want to feel good during the cycle. In the example above I’ve deployed Enclomiphene as a SARM+SERM protocol to act as a test base and a PCT.
This stack can also be used for cutting, with the addition of either:
- Cardarine
- GW0742
- SR9009
- SR9011
I do not recommend stacking YK 11 for cutting cycles. And my reasoning is simple: it would be a waste of muscle-building potential to use something as strong as YK-11 on a caloric deficit.
PCT & Test Base for YK11 Stacks
Stacking YK 11 with any other SARM, no matter how strong, should be treated as a highly suppressive cycle.
Meaning that you will have to do a PCT, and a test base if you want to function normally during and after your cycle.
This can be done using what is known as SERMs (selective estrogen receptor modulators).
SERMs are drugs that bodybuilders use to restart their natural testosterone production after a suppressive cycle with the goal of returning it to baseline levels.
SARM + SERM
The most convenient way of doing both a test base and a PCT after a YK-11 stack is by deploying a SERM on cycle, also known as a SARM+SERM protocol.
The only SERM powerful enough to be used as a test base during a highly suppressive cycle is Enclomiphene.
The following instructions apply to any YK-11 / SARM combination:
- Begin taking the SERM (Enclomiphene) after the second week of your cycle
- Take Enclomiphene for a total of 8 weeks (6 during the cycle, 2 post-cycle)
- Take 12.5 mg/day, and taper down the dose to 6.26 mg/day during the final week
After the final week of Enclomiphene use check your Free Testosterone and LH levels by doing bloodwork. The reason why I choose Enclomiphene is that it’s the only SERM strong enough to be used as a test base for highly suppressive cycles.
By the end of the cycle, your Free Test and LH levels should be in the upper healthy range.
Your YK-11 SARM+SERM cycle should look like this:
WEEK | SARM | YK 11 | ENCLLOMIPHENE |
|---|---|---|---|
1 | x mg/day | ||
2 | x mg/day | ||
3 | x mg/day | 12.5mg/day | |
4 | x mg/day | 12.5mg/day | |
5 | x mg/day | 5mg/day | 12.5mg/day |
6 | x mg/day | 5mg/day | 12.5mg/day |
7 | x mg/day | 5mg/day | 12.5mg/day |
8 | x mg/day | 5mg/day | 12.5mg/day |
9 | 12.5mg/day | ||
10 | 6.25mg/day |
Conclusion
YK 11 is an incredible compound that can be used for any goal, though most effective when used in bulking stacks.
It will always require you to do some sort of testosterone base, and a PCT, no matter what you stack it with. To leverage its myostatin inhibition benefits fully, it’s ideally used with a SARM + a research chemical like MK 677, Stenabolic or Cardarine in accordance with one’s goals.
Using it simply by itself or with a research chemical that’s not a SARM will be suboptimal if your goal is to get as big as possible.
Sources
- Selective androgen receptor modulator, YK11, regulates myogenic differentiation of C2C12 myoblasts by follistatin expression
- Selective Androgen Receptor Modulator, YK11, Up-Regulates Osteoblastic Proliferation and Differentiation in MC3T3-E1 Cells
- (17α,20E)-17,20-[(1-methoxyethylidene)bis(oxy)]-3-oxo-19-norpregna-4,20-diene-21-carboxylic acid methyl ester (YK11) is a partial agonist of the androgen receptor
