Performance peptides are compounds promoted to build muscle, speed recovery or boost endurance, such as HGH, TB-500, PEG-MGF, ACE-031 and MOTS-c. Apart from growth hormone, none has been shown to improve athletic performance in people, and even growth hormone produced only small gains in trials.[1][2] Almost all are banned in sport by the World Anti-Doping Agency.[14]

What are performance peptides?

Performance peptides are a loose group of hormones, growth factors and experimental drugs used to try to gain muscle, lose fat, recover faster or train longer. Most are not approved medicines. They are usually bought online as “research chemicals” and injected without medical supervision.[20][21][22]

Some are not short peptides at all. Growth hormone and ACE-031 are large proteins, and SLU-PP-332 is a small synthetic molecule.[3][6][8] They differ from healing peptides, which are promoted mainly for injury repair, though TB-500 sits in both groups.

Browse all performance peptides

See all 11 performance peptides ↓

How performance peptides work

Each compound targets a different part of muscle or energy biology:

  • Growth hormone raises IGF-1 and shifts body composition toward lean mass and away from fat.[3]
  • ACE-031 acts as a decoy for the activin type IIB receptor, soaking up myostatin and related proteins that normally limit muscle growth.[6]
  • PEG-MGF is based on a fragment of a form of IGF-1 that muscle makes after strain. When drug company scientists tried to reproduce claimed effects in muscle cells, the MGF peptide had no apparent effect.[10]
  • TB-500 is a seven-amino-acid piece of thymosin beta-4, a protein involved in cell movement. It promoted wound repair in aged mice.[11]
  • MOTS-c and SLU-PP-332 target the cell’s energy systems. Exercise raised MOTS-c levels in human muscle, and MOTS-c injections improved physical performance in mice.[9] SLU-PP-332 made mice run about 70% longer.[8]
  • Dermorphin is a mu-opioid agonist, acting on the same receptor as morphine. It was hundreds to thousands of times more potent than morphine when injected into the brains of rats.[12] Its doping use is pain masking, not muscle building.

What human studies actually show

Only growth hormone and ACE-031 have been tested in controlled human trials relevant to muscle.

  • Growth hormone: a 2008 systematic review found that it increased lean mass but did not clearly improve strength or exercise capacity.[1] A 2010 trial in 96 recreational athletes found a 3.9% gain in sprint capacity, with no change in strength, power or endurance, and the gain faded after stopping.[2] In healthy older adults, growth hormone caused swelling, joint pain and carpal tunnel syndrome more often than in those not given it.[5]
  • ACE-031: at the highest dose, a single injection raised lean mass by 3.3% and thigh muscle volume by 5.1% within a month in healthy postmenopausal women.[6] A trial in boys with Duchenne muscular dystrophy was stopped because of nosebleeds and small dilated blood vessels.[7]
  • Everything else: TB-500, PEG-MGF, MOTS-c and SLU-PP-332 have no published human performance trials. Their claims come from cell and animal research.[8][9][10][11]

Extra lean mass is not the same as better performance. In the 2010 athlete trial, much of the lean mass gained on growth hormone was extra body water, and it did not translate into more strength or endurance.[2] Muscle-building effects in animals, such as larger fibers or longer running times, also say nothing about whether a compound is safe to inject repeatedly in people. Dermorphin, the one opioid on this list, has only been given to people in a few small 1980s experiments, mostly on pain (see our dermorphin profile), and never tested for sport.

WADA and anti-doping rules for peptides

WADA’s 2026 Prohibited List, in effect from 1 January 2026, covers nearly every compound on this page. All of the following are banned at all times, in and out of competition:[14]

  • S2.2, peptide hormones: growth hormone, its analogs and fragments, including AOD-9604; and growth hormone-releasing factors such as tesamorelin, CJC-1295 and ipamorelin.
  • S2.3, growth factors: mechano growth factors (MGFs), IGF-1 and its analogs, and thymosin beta-4 and its derivatives, naming TB-500.
  • S4.3, activin receptor IIB blockers: names ACE-031.
  • S4.4, metabolic modulators: AMPK activators, naming MOTS-c, plus insulins.
  • S0, non-approved substances: any drug with no government approval for human use that is not covered elsewhere on the list, including preclinical and discontinued drugs. In our reading this covers SLU-PP-332 and dermorphin, which the list does not name.

Anti-doping labs actively develop tests for these compounds; researchers have already mapped how SLU-PP-332 breaks down in human liver preparations so it can be detected.[23] Dermorphin shows that testing extends beyond human sport: racehorses tested positive for it in 2012, and racing regulators suspended trainers.[25][13]

Safety, legality and black-market risks

FDA status: only growth hormone is FDA-approved, and only for conditions such as growth hormone deficiency, not for performance, bodybuilding or anti-aging.[3] In the US, distributing HGH for any other purpose is a federal crime.[4] FDA lists TB-500, MOTS-c and PEG-MGF among substances nominated for compounding and then withdrawn, saying it has no human exposure data for them.[15] FDA advisers reportedly voted in July 2026 to recommend TB-500 and MOTS-c for compounding, but those votes are not binding.[24] Dermorphin does not appear on FDA’s 503A nominations list.[16]

Black-market products: what is sold is often not what the label says.

  • Anti-doping scientists tested 14 products sold as ACE-031; none contained the actual drug.[17]
  • Products sold as MGF have turned out to be modified analogs.[18]
  • Lab testing of products sold as TB-500 and “TB1000” found misbranded and adulterated contents.[19]

For growth hormone and its releasing peptides, see growth hormone peptides. For mitochondrial compounds such as MOTS-c in the context of blood sugar and energy, see metabolic peptides.