How BCAAs and leucine affect performance and recovery for running, OCR, and endurance sports
Thomas Solomon, PhD.
Updated onReading time approx 7 minutes (1400 words).
What you’ll learn:
BCAAs are three “essential” amino acids — leucine, isoleucine, and valine — that you need to get from food. Leucine can directly signal your muscles to start building new protein after you eat.
Taking BCAAs after hard exercise may reduce next-day muscle soreness and muscle-damage markers.
But neither BCAAs nor leucine are likely to make you run faster, last longer, or jump higher — performance doesn’t really budge.
Curious about the how and why? Scroll down for the details, the nuances, and the nerdy bits.
The information I provide is not medical advice. Supplements can have side effects and might interact with other drugs, nutrients, and medical conditions. If you are unsure, always consult your doctor to ensure a specific supplement is safe for you to use.
What are BCAAs and leucine?
Proteins in your body are always turning over — they’re built and broken down on repeat. You need a minimum daily protein intake to keep basic functions running, including maintaining muscle. Exercise speeds up both building and breakdown, and after exercise — especially strength work — there’s an “anabolic” window of opportunity when eating protein supplies amino acids that tip the balance toward building. If you want a deeper dive, see veohtu.com/protein, veohtu.com/postexercisenutrition, and veohtu.com/carbohydrateplusprotein.
The proteins in your body include enzymes, peptide hormones, neurotransmitters, and the structural stuff that literally holds you together. They’re built from amino acids. Some amino acids help build proteins; others also have roles in metabolism, immunity, and the nervous system. Your body can make some amino acids from other compounds, but it can’t make others (or make them fast enough) — those are the “essential” amino acids you must get from food.
Humans need 9 essential amino acids: phenylalanine, threonine, tryptophan, methionine, leucine, isoleucine, valine, lysine, and histidine. Three of them — leucine, isoleucine, and valine — are called branched-chain amino acids (BCAAs). BCAAs are a bit special because they help build proteins and can act directly in the body. For example, leucine can signal muscles to increase protein synthesis after a meal (see a systematic review on this topic here). Getting BCAAs from food is easy. Omnivores get them from animal and plant foods. People who eat plant-based can also meet needs by eating a variety of plants. Read more at veohtu.com/protein.
Because leucine can drive muscle building and BCAAs have direct effects, supplements became popular and great marketing pushed them into the stratosphere. But, popularity isn’t the same thing as proven performance magic. So…
What is the scientific evidence on BCAAs and leucine’s impact on athletic performance?
BCAAs are generally safe to take.
Supplementing with BCAAs may reduce post-exercise muscle-damage markers (like creatine kinase in blood) and ease delayed-onset muscle soreness (DOMS) for 24 to 48 hours after tough sessions (often strength or plyometric workouts). The effect sizeAn effect size is a quantitative measure of the magnitude of a relationship or difference between groups in a study. Unlike p-values, effect sizes show how large or meaningful that effect is. Common effect size measures include Cohen’s d, Hedges’ g, eta-squared, and correlation coefficients. is usually moderate to large.
BCAA supplements do not speed the recovery of performance after exercise, nor do they directly improve exercise performance.
In older adults (ages 65 and older), especially people with sarcopenia (muscle loss), daily leucine may help maintain muscle mass (see here, here, and here), but the impact on strength and performance is not convincing. Right now, adequate daily protein plus resistance training looks like the best combo to maintain muscle, strength, and function in older age (see here). There isn’t a meta-analysisA meta-analysis quantifies the overall effect size of a treatment by compiling effect sizes from all known studies of that treatment. of leucine and performance in younger adults.
In general, this research field is small and results are variable. Studies differ in training status, BCAA dose, timing, and how much muscle damage the exercise causes. We need more high-quality randomised controlled trialsThe “gold standard” approach for determining whether a treatment has a causal effect on an outcome of interest. In such a study, a sample of people representing the population of interest is randomised to receive the treatment or a no-treatment placebo (control), and the outcome of interest is measured before and after exposure to the treatment and control..
If you choose to use BCAAs or leucine, a reasonable dose is:
2 to 3 grams per day of leucine, or a BCAA mix that provides about 2 grams per day of leucine, about 1 gram per day of isoleucine, and about 1 gram per day of valine. Note: based on effective doses used in research.
Taking more doesn’t necessarily mean a bigger effect.
And, don’t forget that whole foods can easily meets your needs:
100 grams of roasted chicken provides about 2.6 grams of leucine, about 1.5 grams of isoleucine, and about 1.5 grams of valine, plus about 24 grams of total protein, about 13 grams of fat including 3 grams of polyunsaturates, some sodium and potassium, and a little iron and vitamin A.
100 grams of tofu provides about 1.4 grams of leucine, about 0.8 grams of isoleucine, and about 0.9 grams of valine, plus about 10 grams of total protein, about 5 grams of fat (mostly unsaturated), and some sodium, potassium, calcium, and iron.
Can BCAAs and leucine enhance athletic performance?
Supplementation with BCAAs is likely to improve recovery from exercise.
The effect sizeAn effect size is a standardized measure of the magnitude of an effect of an intervention. Unlike p-values, effect sizes show how large the effect is and indicate how meaningful it might be. Common effect size measures include standardised mean difference (SMD), Cohen’s d, Hedges’ g, eta-squared, and correlation coefficients. is medium to large.
The effect appears to be similar between trained athletes and untrained folks, and between males and females.
However, taking a daily dose of BCAAs or leucine or taking a single-dose before/during/after exercise is very unlikely to improve performance.
Keep in mind: because there is moderate heterogeneityHeterogeneity shows how much the results in different studies in a meta-analysis vary from each other. It is measured as the percentage of variation (the I2 value). A rule of thumb: if I2 is roughly 25%, that indicates low heterogeneity (good), 50% is moderate, and 75% indicates high heterogeneity (bad). High heterogeneity means there’s more variability in effects between studies and, therefore, a less precise overall effect estimate. (variability) in effects between studies, mixed risk of biasRisk of bias in a meta-analysis refers to the potential for systematic errors in the studies included in the analysis. Such errors can lead to misleading/invalid results, and unreliable conclusions. ratings, and some (but not all) meta-analyses find evidence for publication biasPublication bias in meta-analysis occurs when studies with significant results are more likely to be published than those with non-significant findings, leading to distorted conclusions. This bias can inflate effect sizes and misrepresent the true effectiveness of interventions, making it crucial to identify and correct for it in research.. So, the overall certainty of evidenceCertainty of evidence tells us how confident we are that the results reflect the true effect. It’s based on factors like study design, risk of bias, consistency, directness, and precision. Low certainty means more doubt and less confidence, and that future studies could easily change the conclusions. High certainty means that the current evidence is so strong and consistent that future studies are unlikely to change conclusions. (confidence) is low-to-moderateA moderate quality of evidence means that, in general, studies in this field have some limitations. This could be due to somewhat inconsistent effects between studies, a moderate range of effect sizes between studies, and/or a moderate risk of bias (caused by a small to medium number of studies, small to medium numbers of participants, poorly described randomization processes, some missing data, some inappropriate methods/statistics). When the quality of evidence is moderate, there is some doubt and only moderate confidence in the overall effect of an intervention, and future studies could change overall conclusions. The best way to improve the quality of evidence is for scientists to conduct large, well-controlled, high-quality randomized controlled trials. for performance and recovery. Therefore, additional high-quality randomised controlled trialsThe “gold standard” approach for determining whether a treatment has a causal effect on an outcome of interest. In such a study, a sample of people representing the population of interest is randomised to receive the treatment or a no-treatment placebo (control), and the outcome of interest is measured before and after exposure to the treatment and control. are needed to increase confidence in the overall effect sizes reported in meta-analysesA meta-analysis quantifies the overall effect size of a treatment by compiling effect sizes from all known studies of that treatment..
Eating whole foods that contain protein provides us with the entire range of amino acids in adequate amounts. For this reason, when following a healthy eating pattern with an adequate daily protein intake, there is absolutely no rational basis for supplementing with specific amino acids. This is because drinking a BCAA-containing drink or taking a leucine pill doesn’t initiate any magic on top of high-quality protein you have already ingested.
In fact, supplementing with such things while neglecting whole foods may leave you deficient in total protein and lacking in other specific amino acids. So, if you want to “branch” out and get your BCAA fix, go and eat some tasty protein-containing whole food.
The nice part: BCAAs and leucine do not appear to have a detrimental effect on recovery or performance. So, if you like it and believe it works for you, give it a whirl. But, remember that time and money spent trying to improve your performance with something that has no obvious benefit might be better spent optimising your training load, sleep habits, and dietary/nutritional choices.
To minimise the risk of consuming a supplement that contains prohibited substances, only choose products that have been independently tested (e.g., Informed Sport). And, remember: Supplements do not make athletes and do not replace training; they're just the icing on a very well-baked cake. Before reaching for pills and potions, optimise your training load and dial in your sleep, nutrition, and rest.
How to use this: If you’re curious, try BCAAs after your hardest strength or downhill sessions for a few weeks and see if soreness drops — keep the dose in the ranges above, keep your daily protein intake adequate, and don’t expect faster times on race day. Track how you feel, then keep or ditch it.
Strengthen the fight for clean sport
Remember: You are the only person responsible for what goes in your body! Ignorance is not an excuse! Stay educated. Be informed.
Consult WADA’s prohibited list, cross-check your meds against the Global DRO drug reference list, and only choose supplements that have been tested by an independent body (e.g., Informed Sport or LabDoor).
Information you can trust. All content on Veohtu is meticulously researched and written by Thomas Solomon, PhD. He does not sell supplements, recovery products, or ad space, and he has no sponsorships, brand affiliations, or ambassador roles. Everything you read reflects his independent views, shaped solely by peer-reviewed scientific evidence — and that will never change.
Full list of meta-analyses examining BCAAs and leucine for performance.
Here are the meta-analyses I've summarised above:
Attenuating Muscle Damage Biomarkers and Muscle Soreness After an Exercise-Induced Muscle Damage with Branched-Chain Amino Acid (BCAA) Supplementation: A Systematic Review and Meta-analysis with Meta-regression. Salem et al. (2024) Sports Med Open
International Society of Sports Nutrition Position Stand: Effects of essential amino acid supplementation on exercise and performance. Ferrando et al. (2023) J Int Soc Sports Nutr
Association of postprandial postexercise muscle protein synthesis rates with dietary leucine: A systematic review. Wilkinson et al. (2023) Physiol Rep
The use of BCAA to decrease delayed-onset muscle soreness after a single bout of exercise: a systematic review and meta-analysis. Martim Gomes Weber, Silas Seolin Dias, Tarlyson Regioli de Angelis, Eduardo Vignoto Fernandes, Andrea Gomes Bernardes, Vinicius Flavio Milanez, Eduardo Inocente Jussiani, Solange de Paula Ramos. Amino acids (2021)
Intake of branched chain amino acids favors post-exercise muscle recovery and may improve muscle function: optimal dosage regimens and consumption conditions. Alejandra Arroyo-Cerezo, Isabel Cerrillo, Ángeles Ortega, María-Soledad Fernández-Pachón. J Sports Med Phys Fitness (2021)
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 Trials. Chutimon Khemtong, Chia-Hua Kuo, Chih-Yen Chen, Salvador J Jaime, Giancarlo Condello. Nutrients (2021)
The effect of branched-chain amino acid on muscle damage markers and performance following strenuous exercise: a systematic review and meta-analysis. Kenji Doma, Utkarsh Singh, Daniel Boullosa, Jonathan Douglas Connor. Appl Physiol Nutr Metab (2021)
Nutritional interventions to improve muscle mass, muscle strength, and physical performance in older people: an umbrella review of systematic reviews and meta-analyses. Gielen E, Beckwée D, Delaere A, De Breucker S, Vandewoude M, Bautmans I; Sarcopenia Guidelines Development Group of the Belgian Society of Gerontology and Geriatrics (BSGG). Nutr Rev (2021)
Effect of Branched-Chain Amino Acid Supplementation on Muscle Soreness following Exercise: A Meta-Analysis. Fedewa MV, Spencer SO, Williams TD, Becker ZE, Fuqua CA. Int J Vitam Nutr Res (2019)
Branched-chain amino acid supplementation and exercise-induced muscle damage in exercise recovery: A meta-analysis of randomized clinical trials. Rahimi MH, Shab-Bidar S, Mollahosseini M, Djafarian K. Nutrition (2017)
Effects of branched amino acids in endurance sports: a review. (SPANISH) Salinas-García ME, Martínez-Sanz JM, Urdampilleta A, Mielgo-Ayuso J, Norte Navarro A, Ortiz-Moncada R. Nutr Hosp (2014)
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Who is Thomas Solomon?
My knowledge has been honed following 20+ years of running, cycling, hiking, cross-country skiing, lifting, and climbing, 15+ years of academic research at world-leading universities and hospitals, and 10+ years advising and coaching in athletic performance and lifestyle change.
I have a BSc in Biochemistry, a PhD in Exercise Science, and over 90 peer-reviewed publications in medical journals.
I'm also an ACSM-certified Exercise Physiologist (ACSM-EP), an ACSM-certified Personal Trainer (ACSM-CPT), a VDOT-certified Distance Running Coach, and a UKVRN Registered Nutritionist (RNutr).
Since 2002, I’ve conducted biomedical research in exercise and nutrition and have taught and led university courses in exercise physiology, nutrition, biochemistry, and molecular medicine.
And, with my personal experience of competing on the track (800m to 10,000m), the road (5 k to marathon), on the trails, and in the mountains, by foot, bicycle, cross-country ski, and during obstacle course races (OCR), I deeply understand what it's like to train and compete — I've been there, done it, and gotten sweat, mud, and tears on my t-shirt.
Disclaimer: I occasionally mention brands and products, but it is important to know that I don't sell recovery products, supplements, or ad space, and I'm not affiliated with / sponsored by / an ambassador for / receiving advertisement royalties from any brands. I have conducted biomedical research for which I’ve received research money from publicly-funded national research councils and medical charities, and also from private companies, including Novo Nordisk Foundation, AstraZeneca, Amylin, the A.P. Møller Foundation, and the Augustinus Foundation. I’ve also consulted for Boost Treadmills and Gu Energy on R&D grant applications, and I provide research and scientific writing services for Examine.com. Some of my articles contain links to information provided by Examine.com but I do not receive any royalties or bonuses from those links. Importantly, none of the companies described above have had any control over the research design, data analysis, or publication outcomes of my work. I research and write my content using state-of-the-art, consensus, peer reviewed, and published scientific evidence combined with my empirical evidence observed in practice and feedback from athletes. My advice is, and always will be, based on my own views and opinions shaped by the scientific evidence available. The information I provide is not medical advice. Before making any changes to your habits of daily living based on any information I provide, always ensure it is safe for you to do so and consult your doctor if you are unsure.