Mechano growth factor has the best name in the peptide catalogue. It sounds like the molecule a muscle makes when it is loaded, and that is roughly how it was discovered. What gym sellers leave out is the next twenty years: no human has been given it in a published study, and when two pharmaceutical companies tried to reproduce its effects on muscle cells, it did nothing. For a tested athlete there is also the List. This page covers status, the evidence and the tests, and gives no usage guidance, per our editorial standards.
What it is, in one paragraph
The IGF-1 gene can be spliced in more than one way. In 1996 Geoffrey Goldspink's group in London reported that one splice form, now called IGF-1Ec in humans, rises in muscle after mechanical stress, and named its product mechano growth factor. The form sold as "MGF" is not the whole protein. It is the 24-amino-acid peptide from the end of that precursor, made from exons 4 to 6 (Thevis 2014), often with substitutions to stop it breaking down, and sometimes with polyethylene glycol attached (PEG-MGF). It is not approved as a medicine anywhere. The related, approved hormone is IGF-1 itself, sold as mecasermin (Increlex) for a rare growth disorder; this site covers the research analogue on IGF-1 LR3.
Status: named, at all times, non-Specified
WADA's 2026 Prohibited List, read on 2026-10-03, names MGF in section S2.3, growth factors and growth factor modulators:
"Insulin-like growth factor 1 (IGF-1, mecasermin) and its analogues; Mechano growth factors (MGFs); Platelet-derived growth factor (PDGF); Thymosin-β4 and its derivatives e.g. TB-500 …"
The List names the class, MGFs in the plural, so PEG-MGF and the substituted versions are covered without being listed one by one. S2 applies at all times, and the List states that every S2 substance is non-Specified, the stricter category for sanction reductions. According to the Cologne laboratory, MGF has been treated as prohibited since 2005 (Thevis 2014). The neighbours on the same line are worth knowing: TB-500 is in the same section, which is why the two are often sold together. The full section map is on WADA status by compound.
Goldspink himself flagged the risk in 2005, in a British Journal of Sports Medicine commentary on MGF's "potential for optimising physical training as well as misuse in doping" (Goldspink 2005).
The evidence, in the order it matters
Human trials: none. PubMed holds 85 records with "mechano growth factor" in the title (2026-10-03). They are cell, animal and gene-expression studies; none gives MGF to a person. ClinicalTrials.gov returns 105 records for an intervention search on "mechano growth factor", but the search engine matches the words loosely. Read title by title, none administers MGF: the hits are IGF-1 therapies, IGF-1 receptor antibodies in cancer, growth hormone studies and cohort studies. A registry hit count is not a count of trials of the compound, a lesson this site learned on MOTS-c.
The human data that do exist measure the gene, not the drug. Exercise studies biopsied muscle and measured how much IGF-1Ec messenger RNA it made after a training bout. Those studies are about what muscle produces on its own. They say nothing about what an injected peptide does.
The replication that failed. In 2014 scientists at Novartis and GlaxoSmithKline set out to reproduce the claimed effects of the MGF peptide: more muscle stem-cell proliferation and delayed fusion into fibres (Fornaro 2014). They tested concentrations up to 500 ng/mL on a mouse muscle cell line, on primary human skeletal muscle myoblasts and on primary mouse muscle stem cells.
| What they tested | MGF peptide | Mature IGF-1 (control) |
|---|---|---|
| Proliferation, mouse C2C12 cells | no increase | increased |
| Proliferation, primary human myoblasts | no increase | increased |
| Delay of fusion into myotubes | no effect | — |
| Primary mouse muscle stem cells | no significant effect | — |
| ERK activation in heart cells (another claimed effect) | no response, native or stabilised | robust response |
Their conclusion: the results "call in to question whether there is a physiological role for MGF". The authors had started from the premise that MGF "could represent a promising strategy to improve muscle regeneration", so the negative result came from teams that set out hoping to use it.
The receptor test. A 2016 study in Rotterdam measured activation of the IGF-1 receptor directly (Janssen 2016). The 24-residue human MGF peptide and the stabilised "Goldspink-MGF" produced no activation. A different product, a "full-length MGF" protein of about 12 kDa that had appeared on the black market, did activate it, but needed about nine times the concentration of IGF-1 for half-maximal effect (EC50 7.83 vs 0.86 nmol/L). That full-length protein is essentially an IGF-1 variant, and it is not what most "MGF" vials claim to contain.
Can a test find it?
Laboratories have published methods for each MGF variant they have found on the market:
- 2012, Ghent. Two black-market products contained a C-terminally amidated MGF analogue; the lab found a diagnostic mass transition that distinguishes it from the body's own form (Esposito 2012).
- 2014, Cologne. A "full-length MGF" offered to athletes and managers, claimed to be undetectable, was characterised (12,264.9 Da, with an R109H substitution) and added to routine testing at 0.25 ng/mL (Thevis 2014).
- 2017, Salt Lake City. MGF R23H turned up in vials confiscated in the USA, alongside BPC-157; in plasma it proved stable enough that it "should be detectable in urine" (Cox 2017).
No paper gives a detection window in people, because nobody has been given MGF under study conditions. USADA's sanctions table, read on 2026-10-03, has no entry naming MGF among 1,075 published sanctions; four name IGF-1. Absence from one agency's published table is not evidence that it is not used.
What the performance claim rests on
The pitch is local muscle repair: inject near a trained muscle and switch on its stem cells. The evidence chain behind it is a gene-expression observation in exercised muscle, early cell work from the discovering laboratory, and animal studies. The independent pharmaceutical replication found no effect on human or mouse muscle cells, and the peptide did not activate the IGF-1 receptor. No human has been given it in a published study, and no trial has measured muscle size, strength or recovery. Against that sits a named, at-all-times, non-Specified listing and published detection methods.
The honest summary
- Named on WADA's 2026 List in S2.3 as "mechano growth factors (MGFs)"; prohibited at all times since 2005; non-Specified.
- 0 human trials: 85 PubMed title records, 105 ClinicalTrials.gov text hits, none administering MGF.
- Novartis and GSK (2014): no effect on proliferation or fusion of human or mouse muscle cells at up to 500 ng/mL.
- Rotterdam (2016): the 24-residue peptide and Goldspink-MGF did not activate the IGF-1 receptor.
- Variants found in black-market and seized products in 2012, 2014 and 2017, each with a published detection method. No published detection window. 0 of 1,075 USADA sanctions name it.
Limits of this page
The registry read covered every record returned by one intervention search on 2026-10-03; a trial registered under a code name would be missed. The early cell and animal studies from the discovering laboratory are summarised through the papers that tested them, not read individually here. Black-market products vary, and what a given vial contains cannot be known from its label. USADA's table covers one agency's published sanctions only.
Sources and dates
- World Anti-Doping Agency, 2026 Prohibited List, sections S2 and S2.3 read 2026-10-03.
- U.S. Anti-Doping Agency, sanctions table, read 2026-10-03: 1,075 entries; none naming MGF or mechano growth factor; four naming IGF-1.
- Goldspink G. Research on mechano growth factor: its potential for optimising physical training as well as misuse in doping. Br J Sports Med 2005;39:787–8 — PMID 16244184
- Esposito S, Deventer K, Van Eenoo P. Characterization and identification of a C-terminal amidated mechano growth factor (MGF) analogue in black market products. Rapid Commun Mass Spectrom 2012;26:686–92 — PMID 22328223
- Fornaro M, Hinken AC, Needle S, et al. Mechano-growth factor peptide, the COOH terminus of unprocessed insulin-like growth factor 1, has no apparent effect on myoblasts or primary muscle stem cells. Am J Physiol Endocrinol Metab 2014;306:E150–6 — PMID 24253050
- Thevis M, Thomas A, Geyer H, Schänzer W. Mass spectrometric characterization of a biotechnologically produced full-length mechano growth factor (MGF) relevant for doping controls. Growth Horm IGF Res 2014;24:276–80 — PMID 25466910
- Janssen JA, Hofland LJ, Strasburger CJ, et al. Potency of full-length MGF to induce maximal activation of the IGF-I R is similar to recombinant human IGF-I at high equimolar concentrations. PLoS One 2016;11:e0150453 — PMID 26991004
- Cox HD, Miller GD, Eichner D. Detection and in vitro metabolism of the confiscated peptides BPC 157 and MGF R23H. Drug Test Anal 2017;9:1490–8 — PMID 28035768
- PubMed E-utilities, "mechano growth factor"[ti] OR "mechano-growth factor"[ti]: 85 records, 2026-10-03. ClinicalTrials.gov API v2, intervention search "mechano growth factor": 105 records, all titles and intervention names read, 0 administering MGF, 2026-10-03. openFDA Drugs@FDA: mecasermin (INCRELEX, IPLEX) present; no MGF product, 2026-10-03.