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Branched-Chain Amino Acids

Branched-chain amino acids are leucine, isoleucine, and valine, three essential amino acids from protein foods that muscles use as building blocks and fuel. People mostly look at them for muscle recovery, where the evidence is moderate, but a single study of 12 people measuring ammonia after exercise found mixed results. Other studies were also small, and several found no clear difference in things like blood glucose or stress hormones.

Sources: PMID 20601741

Best evidence
Grade B
Conditions studied
12
Outcomes
56
Graded outcomes
0257

Evidence by condition

  • Strong
  • Moderate
  • Limited
  • Very limited

12 conditions

Aerobic Exercise Performance

Aerobic Exercise Performance: outcomes studied for Branched-Chain Amino Acids
GradeOutcomeEffectSizeStudiesPeopleStudies list
Aerobic Exercise Metrics

Small Improvement

Improves (the measure goes up)Small effect3 studies235 people

Studies that measured aerobic exercise metrics

Blood glucose

No effect

NoneNo effect7 people
Fat OxidationImproves (the measure goes up)1 study7 people

Studies that measured fat oxidation

Blood Lactate (Exercise)Changes; see studies7 people
Fatigue SymptomsChanges; see studies218 people
Ketone BodiesImproves (the measure goes up)7 people

Running Performance

Running Performance: outcomes studied for Branched-Chain Amino Acids
GradeOutcomeEffectSizeStudiesPeopleStudies list
Aerobic Exercise Metrics

Small Improvement

Improves (the measure goes up)Small effect3 studies225 people

Studies that measured aerobic exercise metrics

Fat OxidationImproves (the measure goes up)1 study7 people

Studies that measured fat oxidation

Blood glucoseChanges; see studies7 people
Blood Lactate (Exercise)Changes; see studies7 people
Fatigue SymptomsChanges; see studies218 people
Ketone BodiesImproves (the measure goes up)7 people

Muscle Recovery

  • Ammonia
  • Muscle Soreness: changes; see studies
  • Blood Lactate (Exercise): changes; see studies
Muscle Recovery: outcomes studied for Branched-Chain Amino Acids
GradeOutcomeEffectSizeStudiesPeopleStudies list
Ammonia

Mixed effect

1 study12 people

Studies that measured ammonia

Muscle SorenessChanges; see studies2 studies78 people

Studies that measured muscle soreness

Blood Lactate (Exercise)Changes; see studies12 people
Creatine KinaseChanges; see studies161 people
InsulinChanges; see studies12 people
Lactate DehydrogenaseImproves (the measure goes up)69 people
Power OutputImproves (the measure goes up)12 people

Ski Performance

  • Weight: improves
  • Fatigue Symptoms: improves
Ski Performance: outcomes studied for Branched-Chain Amino Acids
GradeOutcomeEffectSizeStudiesPeopleStudies list
Weight

Small Decrease

Improves (the measure goes down)Small effect1 study24 people

Studies that measured weight

Fatigue Symptoms

Small Improvement

Improves (the measure goes down)Small effect24 people

Healthy Muscle Aging

  • Fatigue Symptoms: improves
  • Muscle Soreness: changes; see studies
Healthy Muscle Aging: outcomes studied for Branched-Chain Amino Acids
GradeOutcomeEffectSizeStudiesPeopleStudies list
Fatigue Symptoms

Small Improvement

Improves (the measure goes down)Small effect21 people
Muscle SorenessChanges; see studies2 studies21 people

Studies that measured muscle soreness

Sailing Performance

  • Fatigue Symptoms: improves
  • Cortisol
  • Heart Rate: changes; see studies
Sailing Performance: outcomes studied for Branched-Chain Amino Acids
GradeOutcomeEffectSizeStudiesPeopleStudies list
Fatigue Symptoms

Small Improvement

Improves (the measure goes down)Small effect12 people
Cortisol

No effect

NoneNo effect1 study12 people

Studies that measured cortisol

Heart RateChanges; see studies1 study12 people

Studies that measured heart rate

Power OutputImproves (the measure goes up)12 people

Fatigue

  • Cortisol
  • Heart Rate: changes; see studies
  • Fatigue Symptoms: changes; see studies
Fatigue: outcomes studied for Branched-Chain Amino Acids
GradeOutcomeEffectSizeStudiesPeopleStudies list
Cortisol

No effect

NoneNo effect1 study12 people

Studies that measured cortisol

Heart RateChanges; see studies1 study12 people

Studies that measured heart rate

Fatigue SymptomsChanges; see studies12 people
Power OutputImproves (the measure goes up)12 people
Processing AccuracyImproves (the measure goes up)12 people

Mental Resilience

  • Cortisol
  • Heart Rate: changes; see studies
  • Fatigue Symptoms: changes; see studies
Mental Resilience: outcomes studied for Branched-Chain Amino Acids
GradeOutcomeEffectSizeStudiesPeopleStudies list
Cortisol

No effect

NoneNo effect1 study12 people

Studies that measured cortisol

Heart RateChanges; see studies1 study12 people

Studies that measured heart rate

Fatigue SymptomsChanges; see studies12 people
Processing AccuracyImproves (the measure goes up)12 people

General Athletic Performance

  • Cortisol
  • Heart Rate: changes; see studies
  • Fatigue Symptoms: changes; see studies
General Athletic Performance: outcomes studied for Branched-Chain Amino Acids
GradeOutcomeEffectSizeStudiesPeopleStudies list
Cortisol

No effect

NoneNo effect1 study12 people

Studies that measured cortisol

Heart RateChanges; see studies1 study12 people

Studies that measured heart rate

Fatigue SymptomsChanges; see studies12 people
Power OutputImproves (the measure goes up)12 people
Processing AccuracyImproves (the measure goes up)12 people

Cycling Performance

  • Anaerobic Capacity
  • Fat Oxidation: improves
  • Heart Rate: changes; see studies
Cycling Performance: outcomes studied for Branched-Chain Amino Acids
GradeOutcomeEffectSizeStudiesPeopleStudies list
Anaerobic Capacity

No effect

NoneNo effect7 people
Fat OxidationImproves (the measure goes up)1 study7 people

Studies that measured fat oxidation

Heart RateChanges; see studies1 study7 people

Studies that measured heart rate

Fatigue SymptomsChanges; see studies7 people
Oxygen UptakeImproves (the measure goes up)7 people
Rating of Perceived ExertionImproves (the measure goes up)7 people

Soccer Performance

  • Adrenaline
  • Fat Oxidation: improves
  • Blood glucose: changes; see studies
Soccer Performance: outcomes studied for Branched-Chain Amino Acids
GradeOutcomeEffectSizeStudiesPeopleStudies list
Adrenaline

No effect

NoneNo effect10 people
Fat OxidationImproves (the measure goes up)1 study10 people

Studies that measured fat oxidation

Blood glucoseChanges; see studies10 people
Blood Lactate (Exercise)Changes; see studies10 people
DopamineImproves (the measure goes up)10 people
Fatigue SymptomsChanges; see studies10 people
NoradrenalineImproves (the measure goes up)10 people
Reaction TimeImproves (the measure goes up)10 people

Cognitive Improvement

  • Fatigue Symptoms: changes; see studies
Cognitive Improvement: outcomes studied for Branched-Chain Amino Acids
GradeOutcomeEffectSizeStudiesPeopleStudies list
Fatigue SymptomsChanges; see studies224 people

Key findings

  • Aerobic Exercise MetricsAerobic Exercise PerformanceImproves (the measure goes up)
  • AmmoniaMuscle Recovery
  • WeightSki PerformanceImproves (the measure goes down)

Shop the evidence-backed picks

Third-party tested Branched-Chain Amino Acids products, in the forms the graded studies used where we can match them.

  • Grade B

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Studies cited

11 studies from PubMed

  1. Effects of branched-chain amino acids supplementation on physiological and psychological performance during an offshore sailing raceEur J Appl Physiol · PMID 18704484
  2. Branched-chain amino acid supplementation before squat exercise and delayed-onset muscle sorenessInt J Sport Nutr Exerc Metab · PMID 20601741
  3. Does Branched-Chain Amino Acids (BCAAs) Supplementation Attenuate Muscle Damage Markers and Soreness after Resistance Exercise in Trained Males? A Meta-Analysis of Randomized Controlled TrialsNutrients · PMID 34072718
  4. Influence of ingesting a solution of branched-chain amino acids on perceived exertion during exerciseActa Physiol Scand · PMID 9124069
  5. Branched-chain amino acid supplementation during repeated prolonged skiing exercises at altitudeInt J Sport Nutr · PMID 8876349
  6. The effect of branched chain amino acids on psychomotor performance during treadmill exercise of changing intensity simulating a soccer gameAppl Physiol Nutr Metab · PMID 22050133
  7. Energy expenditure during 2-day trail walking in the mountains (2,857 m) and the effects of amino acid supplementation in older men and womenEur J Appl Physiol · PMID 21744005
  8. Ingestion of branched-chain amino acids and tryptophan during sustained exercise in man: failure to affect performanceJ Physiol · PMID 7473239
  9. Branched-chain amino acids supplementation enhances exercise capacity and lipid oxidation during endurance exercise after muscle glycogen depletionJ Sports Med Phys Fitness · PMID 21297567
  10. Administration of branched-chain amino acids during sustained exercise--effects on performance and on plasma concentration of some amino acidsEur J Appl Physiol Occup Physiol · PMID 1748109
  11. Effect of branched-chain amino acid supplementation on mental performanceActa Physiol Scand · PMID 1962526

Protocols that include Branched-Chain Amino Acids