REF-153 · Ferrando et al. / ISSN, 2023 · Journal of the International Society of Sports Nutrition, Vol. · Paper

International Society of Sports Nutrition Position Stand: Effects of essential amino acid supplementation on exercise and performance

Astrong evidenceMeasured on a mixed groupWritten before October 2026, being re-checked

Key Findings — the ten ISSN positions (abstract)

1. Role of EAA: the primary effect of EAAs on skeletal muscle is stimulation of muscle protein synthesis (MPS) and turnover; turnover replaces degraded or damaged proteins and is the metabolic foundation for functional performance.

2. Free-form EAA kinetics: supplementation with free-form EAAs produces a quick rise in peripheral EAA concentrations, which stimulates MPS.

3. Safety: the safe upper limit of EAA intake, absent inborn metabolic disease, easily accommodates additional supplementation.

4. Dose at rest:

ContextDose (abstract)
MPS stimulation at rest beginsrelatively small dosages: 1.5-3.0 g EAA
MPS plateau~15-18 g EAA

5. Non-essential amino acids are not required for the EAA-induced MPS stimulation.

6. Free EAA vs intact protein: free-form EAA ingestion stimulates MPS more than an equivalent amount of intact protein.

7. Repeated dosing: repeated EAA-induced MPS stimulation through the day does not diminish the anabolic effect of meal intake.

8. Aging: direct comparisons of formulas are lacking, but aging requires a greater proportion of leucine to overcome anabolic resistance.

9. Without exercise: EAA supplementation can enhance functional outcomes in anabolic-resistant populations.

10. Caloric deficit: EAA requirements rise during a caloric deficit; meeting whole-body EAA requirements then preserves anabolic sensitivity in skeletal muscle.

Practical Application

ISSN position stand: at rest, muscle protein synthesis is stimulated by 1.5-3.0 g of essential amino acids and plateaus around 15-18 g; free-form EAAs raise blood EAA quickly and stimulate MPS more than the same amount of intact protein; non-essential amino acids are not needed; the safe upper limit easily accommodates supplementation; aging needs a greater leucine share; and EAA requirements rise in a caloric deficit. A complete protein meal already carries EAAs — supplementation is a tool for the gaps: a deficit, an older athlete, or a moment when intact protein is impractical.
Caloric deficit: the one situation the stand singles out — when cutting weight, protect the EAA intake first (position 10).
Older athletes: favour a higher leucine proportion (position 8); the stand does not give a gram value.
Not from this paper; the base's own practice: the everyday route to EAAs is protein-rich meals and, when convenient, whey after training and casein before sleep (see REF-154, REF-155 for the timing evidence); an EAA product is a supplement to that, not a replacement for protein.

Limitations

Position stand — a consensus over heterogeneous studies, largely MPS (a surrogate) rather than performance outcomes; direct comparisons of EAA formulas are lacking (position 8); doses beyond the rest-state 1.5-3.0 g threshold and 15-18 g plateau are not given in the abstract.

How this entry was checked and changed
Content correction 2026-09-27
"Optimal dose 6-12 g EAA", "2-3 g leucine per meal (~25 g whey)", "critical at −300 kcal/day", "25-30 g whey = ~12 g EAA / ~2.5 g leucine", "6-10 g EAA before fasted training", "40 g casein = ~16 g EAA", "5-10 g EAA in bottle on >3 h rides", "≥2.5-3 g leucine per serving" -> none are in the abstract; deleted or replaced by the abstract's positions (1.5-3.0 g threshold, 15-18 g plateau).
Positions 7 and 9 (repeated dosing does not blunt meal anabolism; functional gains without exercise in anabolic-resistant populations) added from the abstract.
Timing/route advice relabelled as the base's own practice with pointers to REF-154/REF-155.