Category
Muscle & Performance
Peptides studied for their influence on muscle fiber hypertrophy, satellite cell activation, myostatin inhibition, and recovery from mechanical loading. IGF-1 LR3 and follistatin represent two distinct but complementary mechanisms for increasing muscle mass in research models.
10 peptides in this category
What peptides are studied for muscle growth?
IGF-1 LR3 and follistatin are the most studied peptides for muscle hypertrophy. IGF-1 LR3 activates the mTOR pathway to increase protein synthesis and satellite cell proliferation. Follistatin inhibits myostatin — the primary negative regulator of muscle growth — and its overexpression in animal models produces dramatic increases in muscle mass. MGF (mechano-growth factor), a splice variant of IGF-1, is specifically expressed in response to mechanical loading and plays a distinct role in early satellite cell activation after exercise-induced damage.
Skeletal muscle growth at the cellular level requires satellite cell activation, myonuclei accretion, increased protein synthesis, and suppression of atrophy signaling. Peptides in this category intervene at one or more of these steps. IGF-1 LR3 (long Arg3 IGF-1) is a modified form of insulin-like growth factor 1 with an extended half-life — native IGF-1 is rapidly bound by IGF binding proteins, while the Arg3 substitution reduces this binding, allowing more free IGF-1 to interact with muscle IGF-1 receptors. This activates PI3K/Akt/mTOR signaling and promotes both satellite cell proliferation and protein synthesis.
Follistatin is a glycoprotein that inhibits myostatin and activin A — both members of the TGF-beta superfamily that normally limit muscle growth. Elevated follistatin in animal models produces dramatic muscle mass increases, and certain follistatin-activating peptides or gene therapy approaches have attracted significant research interest. MGF (mechano-growth factor), a splice variant of IGF-1 expressed locally in response to mechanical loading, is another peptide in this class with distinct signaling from systemic IGF-1. The interplay between these systemic and local growth signals is central to understanding how muscle adapts to training.
Compounds
Peptides in this category
ACE-031
Phase IIACVR2B-Fc · Bimagrumab-precursor
ACE-031 is a fusion protein of the extracellular domain of activin type IIB receptor (ACVR2B) fused to human IgG1 Fc. It acts as a myostatin/activin trap, sequestering multiple TGF-β superfamily ligands (myostatin, GDF-11, activin A) that inhibit muscle growth. Phase 2 trials in Duchenne muscular dystrophy showed significant lean muscle mass gains before being halted for safety signals (nosebleeds, telangiectasias). Related compound bimagrumab continues development.
Anserine
PreclinicalBeta-Alanyl-N-methyl-L-histidine
Anserine is a methylated dipeptide analog of carnosine found in high concentrations in avian and fish muscle. It shares carnosine's pH-buffering and antioxidant properties but shows superior blood-brain barrier penetration. Research highlights potential for cognitive decline prevention, reduction of amyloid-beta toxicity, and improved exercise performance. It is often studied alongside carnosine for synergistic effects.
Carnosine
PreclinicalBeta-Alanyl-L-Histidine · L-Carnosine
Carnosine is a naturally occurring dipeptide (β-alanyl-L-histidine) found at high concentrations in skeletal muscle and the brain. It acts as a pH buffer in muscle (reducing acidosis during high-intensity exercise), a powerful antioxidant, an antiglycation agent (preventing protein-sugar crosslinking), and a chelator of zinc and copper. Research explores its role in aging, cognitive decline, autism, and exercise performance.
Collagen Peptides
PreclinicalHydrolyzed Collagen · Collagen Hydrolysate
Hydrolyzed collagen peptides are short-chain amino acid sequences (2–20 amino acids) produced by enzymatic hydrolysis of collagen. Research demonstrates that specific collagen dipeptides and tripeptides (Pro-Hyp, Hyp-Gly) are absorbed intact, reach fibroblasts in skin and joints, and stimulate collagen and hyaluronic acid synthesis. Meta-analyses support effects on skin elasticity, wrinkle depth, joint pain, and muscle mass when combined with resistance exercise.
Follistatin-344
PreclinicalFST-344 · Follistatin isoform 344
Follistatin-344 is an isoform of follistatin, an endogenous glycoprotein that binds and neutralizes myostatin (GDF-8) and activin, thereby releasing the natural inhibition on muscle growth. Without myostatin's inhibitory signal, satellite cells proliferate and muscle fiber hypertrophy is dramatically enhanced. Gene therapy studies in animals and in rare myostatin-null humans demonstrate extreme muscle mass increases, driving significant research interest.
GDF-11
PreclinicalGrowth Differentiation Factor 11 · Bone Morphogenetic Protein 11
GDF-11 is a member of the TGF-β superfamily that generated significant excitement when studies reported it as a "rejuvenating factor" in young parabiosis mouse blood. Subsequent research has been highly contested — some studies suggest it reverses cardiac hypertrophy and restores skeletal muscle and neural stem cell function in aged mice, while others find it increases with age and impairs muscle regeneration. It remains one of the most debated factors in aging biology.
IGF-1 LR3
PreclinicalLong R3 IGF-1 · Insulin-like Growth Factor 1 Long R3
IGF-1 LR3 is a modified version of Insulin-like Growth Factor-1 with an arginine substitution and 13-amino-acid N-terminal extension, which reduces binding to IGF-binding proteins and extends its half-life. It promotes muscle cell hyperplasia and hypertrophy by activating the PI3K/AKT/mTOR pathway. Research explores its role in muscle wasting, recovery from injury, and anabolic signaling.
Mechano Growth Factor
PreclinicalMGF · IGF-1Ec
Mechano Growth Factor (MGF) is a splice variant of the IGF-1 gene expressed in response to mechanical loading and muscle damage. Unlike systemic IGF-1, MGF activates satellite cells (muscle stem cells) to proliferate before differentiating — a critical step in muscle repair and growth. Research indicates it plays a distinct, non-overlapping role with systemic IGF-1 in tissue regeneration.
PEG-MGF
PreclinicalPEGylated Mechano Growth Factor
PEG-MGF is a PEGylated (polyethylene glycol-modified) form of Mechano Growth Factor, designed to dramatically extend its biological half-life from minutes to days while preserving activity. PEGylation allows systemic delivery and sustained satellite cell activation without the need for local injection. Research shows enhanced muscle hypertrophy signaling compared to unmodified MGF.
TB-500
PreclinicalThymosin Beta-4 Fragment · Tβ4 fragment
TB-500 is a synthetic version of the active region of Thymosin Beta-4, a naturally occurring peptide found in virtually all human cells. Research shows it promotes actin polymerization and cell migration, which accelerates wound healing, muscle repair, and vascular growth. It is particularly studied for its ability to reduce inflammation and promote cardiac tissue repair.
C₂₁₂H₃₅₀N₅₆O₇₈S · 4963.44 Da
Research applications
What researchers are studying
Myofibrillar protein synthesis
IGF-1 LR3 activates the mTOR pathway in skeletal muscle, increasing ribosomal biogenesis and translational efficiency for myosin heavy chain and actin synthesis. In cell culture and animal models, it produces significant increases in muscle fiber cross-sectional area, and is used extensively in myogenesis research as a positive control for anabolic signaling.
Myostatin inhibition and hyperplasia
Follistatin-344 and follistatin-315 are the two main isoforms studied in research. By sequestering myostatin, they remove the primary brake on muscle growth, allowing satellite cell proliferation and fiber hypertrophy beyond what IGF-1/mTOR alone would produce. Myostatin knockout mice exhibit roughly double the muscle mass of wild-type animals, illustrating the magnitude of this pathway's effect.
Recovery from eccentric damage
MGF is expressed acutely in response to muscle fiber damage from eccentric loading. Its role appears to be in activating quiescent satellite cells and priming them for proliferation before systemic IGF-1 takes over for the later anabolic phase. Understanding this temporal separation between local (MGF) and systemic (IGF-1) growth signaling has changed how researchers model exercise-induced hypertrophy.
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