The Claim
ACE-031 treatment for 14 weeks in common marmosets does not alter the proportion of type I and type II muscle fibers in the biceps brachii, maintaining a stable 16% type I fiber composition.
What the research says
Supports is higher
Support is ahead, but a single strong opposing study can change this.
These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.
In common marmosets treated with ACE-031 for 14 weeks, the percentage of type I muscle fibers in the biceps brachii remains at 16%, and the ratio of type I to type II fibers does not change.
See the scientific wording
ACE-031 treatment for 14 weeks in common marmosets does not alter the proportion of type I and type II muscle fibers in the biceps brachii, maintaining a stable 16% type I fiber composition, suggesting that ActRIIB inhibition promotes hypertrophy without inducing fiber type transitions.
A protein that blocks signals from myostatin and activin A binds to these signals in the blood, preventing them from reaching muscle cells. Without these signals, muscle cells stop breaking down proteins and start building more, making each muscle fiber thicker. This thickening happens in both slow-twitch and fast-twitch fibers equally, so the percentage of each type stays the same.
What the research says
1 studyACE-031 made the marmoset's muscle fibers thicker, but didn't change whether they were slow or fast fibers — the mix stayed exactly the same, just bigger.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.