Taking BCAAs after weightlifting doesn't seem to change certain other muscle proteins (Akt and GSK-3) that are involved in other processes, so they probably aren't part of how BCAAs help build muscle.
Scientific Claim
BCAAs do not affect Akt or GSK-3 phosphorylation in human skeletal muscle during recovery from resistance exercise, suggesting these pathways may not be involved in BCAA-mediated protein synthesis effects.
Source Excerpt
“When BCAAs were supplied to subjects during and after one session of quadriceps muscle resistance exercise, an increase in mTOR, p70 S6 kinase, and S6 phosphorylation was found in the recovery period after the exercise with no effect of BCAAs on Akt or glycogen synthase kinase 3 (GSK-3) phosphorylation.”
Evidence from Studies
Supporting Studies
Branched-chain amino acids activate key enzymes in protein synthesis after physical exercise.
The study specifically reports no effect of BCAAs on Akt or GSK-3 phosphorylation during recovery from resistance exercise. This is a negative finding that helps narrow down which pathways are involved in BCAA effects.
⚠️ Overstated
The study design is unclear (Level 5 evidence), and the claim uses 'do not affect' which implies causation. The study only shows no association, not that BCAAs don't affect these pathways.
More accurate phrasing:
“BCAAs are not associated with changes in Akt or GSK-3 phosphorylation in human skeletal muscle during recovery from resistance exercise, suggesting these pathways may not be involved in BCAA-mediated protein synthesis effects.”