BCAAs
Last reviewed October 2026 · Based on 14 studies
Bottom line
BCAA supplements may ease muscle soreness after hard training, most clearly in regular exercisers, though the trials are small and inconsistent. They have not been shown to improve endurance performance, and the evidence for building muscle is weak.
What it helps with
- Eases muscle soreness after exercise — Benefit, evidence grade C (Limited). Several meta-analyses of small trials; downgraded for inconsistency (a 2017 review found no soreness effect) and small total sample.
- Lowers muscle damage markers after exercise — Benefit, evidence grade C (Limited). Blood marker rather than symptoms; several small trials and a 2017 meta-analysis; downgraded for surrogate outcome.
- Works best when taken before or after exercise — Mixed results, evidence grade C (Limited). Two small RCTs with opposite conclusions on timing; downgraded for inconsistency and small samples.
- Helps build muscle with resistance training — Mixed results, evidence grade C (Limited). Meta-analysis of 12 RCTs with only one of several outcomes improved; indirect evidence from leucine breakdown products. Downgraded for inconsistency and indirectness.
- Preserves lean mass while dieting — Benefit, evidence grade C (Limited). One small RCT of 17 trained men; downgraded for small sample and single trial.
- Improves endurance performance — No effect, evidence grade B (Moderate). Two systematic reviews (24 and 15 studies) found no clear benefit; downgraded once for risk of bias and surrogate outcomes.
- Has no serious side effects in trials — No effect, evidence grade C (Limited). Meta-analysis in people with liver cancer; not tested in healthy people, and safety reporting in trials was limited.
What it is
Branched-chain amino acids (BCAAs) are leucine, isoleucine and valine. Muscle oxidises them during exercise [1], and doses in trials have varied widely [2].
How it might work
Researchers propose that BCAAs stimulate anabolic signals in muscle, which may help recovery after exercise [1]. This is a proposed mechanism, not a proven one.
What the research says
Several meta-analyses found that BCAAs reduce delayed-onset muscle soreness. A 2019 meta-analysis of 8 studies found a large reduction compared with placebo [3]. A 2021 review of 10 trials found soreness reduced 24 to 72 hours after exercise in trained people [2]. A 2024 umbrella review rated the soreness benefit as moderate certainty [4].
A 2017 meta-analysis of 8 trials found lower creatine kinase after exercise but no significant change in soreness [5]. In a 2025 trial, BCAAs taken after resistance training reduced soreness at 48 hours, and post-exercise dosing outperformed pre-exercise dosing [6]. A 2018 pilot found pre-exercise dosing worked better [7].
For muscle, a 2026 meta-analysis in older adults with sarcopenia found only skeletal muscle index improved with BCAA-rich supplements and training [8]. For performance, a 2022 systematic review found negligible benefits in athletes [1], and a 2026 systematic review found no consistent improvement in endurance performance [9].
Doses used in studies
A 2018 pilot used 9.6 g of BCAAs per day [7]. The 2021 review noted that doses up to about 255 mg per kg of body weight a day were used in soreness studies [2].
Safety and interactions
In a meta-analysis of 11 studies in people with liver cancer, oral BCAAs were relatively safe, with no serious adverse events [10]. No data were found on upper intake limits or toxic doses, interactions with medicines, pregnancy or breastfeeding, or kidney disease in the studies cited here.
Caveats and open questions
Most trials are small, and studies often did not report total daily protein intake [1]. Results depend on training status, dose and severity of muscle damage, so benefits for untrained people or higher doses are unknown [2]. Reviews disagree on soreness, and most of the endurance evidence is negative [5][9].
References
- Oral Branched-Chain Amino Acids Supplementation in Athletes: A Systematic Review.. Nutrients, 2022.
- The use of BCAA to decrease delayed-onset muscle soreness after a single bout of exercise: a systematic review and meta-analysis.. Amino Acids, 2021.
- Effect of branched-Chain Amino Acid Supplementation on Muscle Soreness following Exercise: A Meta-Analysis.. Int J Vitam Nutr Res, 2019.
- Nutritional interventions for exercise-induced muscle damage: an umbrella review of systematic reviews and meta-analyses of randomized trials.. Nutr Rev, 2024.
- Branched-chain amino acid supplementation and exercise-induced muscle damage in exercise recovery: A meta-analysis of randomized clinical trials.. Nutrition, 2017.
- Effect of Timing of Branched-Chain Amino Acid Supplementation on Muscle Recovery after Resistance Training in Healthy Males.. Am J Mens Health, 2025.
- Effect of BCAA supplement timing on exercise-induced muscle soreness and damage: a pilot placebo-controlled double-blind study.. J Sports Med Phys Fitness, 2018.
- Effects of branched-chain amino acid-rich nutritional supplements combined with resistance training on body composition and body function in older patients with sarcopenia.. Arch Gerontol Geriatr, 2026.
- Branched-chain amino acid supplementation and endurance performance: reporting guidelines and systematic review of biochemical vs clinical evidence.. Phys Sportsmed, 2026.
- Efficacy and safety of oral branched-chain amino acid supplementation in patients undergoing interventions for hepatocellular carcinoma: a meta-analysis.. Nutr J, 2015.