PEG-MGF — Research, Dosing & Price Guide

PEG-MGF (PEGylated Mechano Growth Factor) is a PEGylated version of the MGF splice variant of IGF-1 (IGF-1Ec in humans). The addition of polyethylene glycol (PEG) extends its half-life from minutes to hours, enabling systemic administration. MGF is naturally produced in response to mechanical stress on muscle tissue and plays a critical role in activating satellite cells for muscle repair and growth.

MGF is a splice variant of the IGF-1 gene produced specifically in mechanically stressed skeletal muscle and cardiac tissue. While standard IGF-1 splice variants activate the IGF-1 receptor for general growth signaling, MGF has a unique E-domain that preferentially activates muscle satellite cells — the resident stem cells of skeletal muscle. Upon satellite cell activation, these quiescent cells enter the cell cycle, proliferate, and differentiate into new myonuclei that fuse with existing muscle fibers, increasing their capacity for protein synthesis and growth. The PEGylation shields MGF from rapid proteolytic degradation, extending its circulating half-life from approximately 5–7 minutes to several hours, making it practical for systemic injection rather than requiring localized intramuscular administration.

• Goldspink et al. (2004) in the Journal of Physiology demonstrated that MGF is the initial IGF-1 splice variant expressed after mechanical damage, preceding IGF-1Ea in the repair sequence
• Hill and Goldspink (2003) showed MGF activated satellite cells more potently than IGF-1Ea in cell culture, driving proliferation rather than differentiation
• Yang and Goldspink (2002) demonstrated local MGF injection increased muscle mass by 20% in mouse studies within 2 weeks
• Research in the Journal of Applied Physiology showed MGF expression declines significantly with age, correlating with reduced satellite cell activation in elderly subjects
• PEGylation studies confirmed extended half-life and maintained biological activity of the conjugated peptide

• Standard dose: 200–400 mcg subcutaneous or intramuscular injection, 2–3 times per week
• Post-workout dosing: inject within 30 minutes of resistance training for maximal satellite cell activation
• Bilateral localized protocol: some users inject directly into trained muscle groups for targeted effects
• Cycle: 4–6 weeks on, 4 weeks off
• Often stacked with IGF-1 LR3 on non-training days and PEG-MGF on training days
• Do not mix PEG-MGF and IGF-1 LR3 in the same injection — they compete for binding sites

Known Side Effects

• Injection site pain and swelling — particularly with intramuscular injection, can be significant
• Hypoglycemia — potential glucose-lowering effects through IGF-1 pathway activation
• Localized muscle soreness — some users report increased DOMS-like symptoms in injected muscles
• Water retention — mild, typically during the first 1–2 weeks
• Theoretical long-term risk of promoting growth in unintended tissues, though not observed in published research

Safety Profile

PEG-MGF is a research compound without human clinical trials. Safety information is extrapolated from preclinical studies and the broader IGF-1 literature. The PEGylation is generally safe — PEG is widely used in pharmaceutical formulations. The primary theoretical concern is systemic growth factor activity, though MGF's preferential action on satellite cells suggests more targeted effects than systemic IGF-1. Individuals with a history of cancer should avoid growth factor peptides. Monitor blood glucose during use, particularly if diabetic or using insulin.

Week 1–2: Enhanced post-workout pump and increased muscle fullness. Some users report faster recovery between training sessions. Mild water retention possible. Weeks 3–4: Noticeable improvements in muscle recovery and growth. Training volume capacity increases as satellite cells become activated and contribute to repair. Weeks 5–6: Peak muscle-building effects. Users report improved body composition, increased muscle density, and enhanced ability to maintain training intensity. After cessation, the newly incorporated myonuclei persist, providing lasting benefit to muscle fiber capacity.

Prices sourced from peptides.gg marketplace. Prices may vary.