amino acid · for low stamina
BCAAs
Tells your muscles to rebuild, and limits the damage hard training does.
Say that in clinical terms
Stimulates muscle protein synthesis via mTOR pathway. Reduces exercise-induced muscle damage and protein degradation.
How strong is the research?
Strong evidence
Studied in a narrower group
4 papers read, 3 supporting.
Who was studied: 12 untrained young Japanese women doing squats.
How much to take
daily
5–20 g
Ratio of 2:1:1 (leucine:isoleucine:valine) most common. Take before/during exercise.
Before you take it
- No NIH/IOM Tolerable Upper Intake Level (UL) has been established for BCAAs. The European BfR has derived a conservative supplemental guidance value of approximately 8.2 g/day total (all three BCAAs combined). Long-term safety data at doses above 20 g/day are limited.
- BCAAs compete with levodopa for the LAT1 large neutral amino acid transporter at the blood-brain barrier; elevated plasma BCAA levels can reduce CNS levodopa availability — a clinically documented interaction for Parkinson's disease patients on levodopa therapy. Neurologist consultation is required before supplementing BCAAs in this population.
- Leucine and isoleucine stimulate pancreatic insulin secretion; high BCAA doses may augment the glucose-lowering effect of insulin or oral hypoglycemic agents, raising theoretical hypoglycemia risk in individuals on those medications.
- Individuals with chronic kidney disease (CKD) face an increased renal nitrogen load from isolated amino acid supplements; those with advanced liver disease have impaired amino acid catabolism. Medical supervision is recommended in both populations before using isolated BCAA products.
- Insufficient safety data exist for use during pregnancy or lactation. Animal data indicate that high BCAA intake during early pregnancy may adversely affect fetal and placental growth. Use during pregnancy or breastfeeding should be physician-supervised.
What we make of it
Twelve people, and it measured soreness rather than stamina.
The detail
The study is a small crossover trial of 12 people, not the pooled analysis we labelled it. What it measured was delayed muscle soreness, which is a different thing from endurance.