What is PEG-MGF or PEGylated mechano growth factor? MGF is a splice variant of the IGF gene which increases stem cell count in the muscle and allows for muscle fibers to fuse and mature. This is a process required for growth of adult muscle. Natural MGF is made locally and does not travel into the bloodstream. Synthetic MGF is water based and when administered intramuscularly, travels into the bloodstream. MGF is only stable in the blood stream for only a few minutes.
PEGylation is the act of attaching a Polyethylene glycol (PEG) structure to another larger molecule (in this case, MGF). The PEG acts as a protective coating and the theory here is that this will allow the MGF to be carried through the blood stream without being broken down.
I have to be honest here, and say that in my estimation, PEGylating MGF is basically something a research chemical company did to have a bit of a market with no competition for awhile. That’s not to say that it’s not a decent product, but honestly, in this particular case, I feel that marketing was in the drivers seat with the development of this version of MGF, and science was in the backseat asking “are we there yet?”.
MGF is produced biologically when muscle fibers are broken down through resistance (weight training). It is a potent factor in muscle growth. MGF stimulates muscle growth, creates new muscle fibers, promotes nitrogen retention and increases protein synthesis. This compound is commonly used for overall growth of muscle and to promote growth in body parts that are not up to par with the rest of the user’s physique. Results usually depend on dosage. Fat loss and strength increases are not typically seen with MGF’s use (as they are in IGF-1 use).
The PEG itself is safe for use as it is approved by the US Food and Drug Administration (FDA) and does not react in the body. The PEG is not broken down in the body and excreted (intact) through urine or feces. Any risk associated PEGylated drugs is due to drug itself not the PEG per se.
In a study on older rodents, muscle fiber reduction in their older muscles was found to be attributed to decreased activity of satellite cells (1). After a certain size was reached, growth ceased. In the presence of MGF, satellite cells became activated and hypertrophy in mature muscles continued.
In experiments where MGF was administered intramuscularly, there was a 20% increase in the weight of the injected muscle fibers within 2 weeks (2). In further studies, it took 4 months for IGF to cause a 25% increase in muscle mass (3). MGF was found to be more potent than IGF-1Ea in rapid muscle growth (4).
[Note: This data is on “regular” MGF, not the Pegylated version….we can assume similar results, however]
Although the science looks impressive on paper, in the real world, we see something totally different. While PEGMGF should have theoretically given the athletes who use it better results than regular MGF, it struggles to provide even the same results at a higher dosage (judging from the athletes I have personally spoken to).
So does that mean it’s useless?
No, not at all. Not entirely…
I think that the PEGylation is actually a potentially useful addition to MGF if properly used. If we assume that the PEGylation will extend the life of the MGF in the body somewhat, then we can use it in a very specific manner to help our gains. It is nowhere near as good as regular MGF though, and I wouldn’t use it unless I really had the disposable cash on hand.
I feel that, based on conversations with several athletes and bodybuilders, that PEGMGF is best used in conjunction with (not instead of) regular MGF (and IGF). I feel that if one were to use my Peptides protocol (to read about that in detail, check out the article “Peptides: The Next Frontier in Hypertrophy”), I think that PEGMGF is probably best used on off-days from training, to keep MGF levels elevated and get additional hypertrophy from the longer releasing PEGMGF.
So, along with regular MGF and Lr3IGF-1, if I felt it to be necessary, I might throw in some PEGMGF on off-days from training, to get additional growth (and again, if it were me, I’d probably recommend 400-500mcg of PEGMGF on off days, with a regular dose of 200mcg of regular MGF + 100mgs of Lr3IGF-1 on training days, as per my article).
For most athletes I’ve spoken to and worked with, this is what we’ve found to be optimal. Again, though…I’m not very fond of this product, and it’s best used (if at all), as a possible adjunct to an IGF + MGF cycle, and never in place of regular MGF. Unfortunately, it just didn’t pan out as people hoped it would, but it’s not a complete waste of money.
- Chakravarthy et al. 2000
- Goldspink, 2001
- Musaro et al. 2001
- Musaro et al. 2001