Quick answer
Research has not settled it. Two small trials in young men disagree: one found 9.6 g a day taken before hard exercise lowered soreness more, and the other found taking BCAAs after training worked better. A 2024 analysis linked longer use in the days before a hard session with larger effects on a muscle damage marker.1,2,3
Key facts
- NIH says it is not clear whether taking protein or BCAAs before or after a workout makes a difference.4
- In 15 young men, 9.6 g a day taken before hard arm exercise lowered soreness more than the same amount taken after.1
- In 24 untrained men, BCAAs taken after resistance training lowered soreness at 48 hours more than BCAAs taken before.2
- Trials in the 2024 analysis gave BCAAs for anything from a single day to 28 days around the hard session.3
Before or after training
Research has not made clear whether taking protein or BCAAs before or after a workout changes how well they build muscle protein.4
The two trials that compared timing head to head point in opposite directions. In the first, 15 young men took 9.6 g a day for several days around one bout of hard arm exercise; those who took their BCAAs before the session had less soreness, swelling and stiffness afterward than those who took them after. In the second, 24 untrained men did a resistance session with BCAAs before or after; soreness at 48 hours was lower with the after-training dose.1,2
Both trials were small and short, and neither can tell you the best minute to drink your BCAAs.1,2
The days before a hard session
In a 2024 analysis of 18 trials, taking BCAAs for more days before the hard exercise was linked to larger effects on a marker of muscle damage.3
The trials in that analysis took different approaches. Some gave a single drink on the day of the hard session. Others started days before and kept going after it: one gave 20 g a day for 7 days before, on the day and for 4 days after, and another gave 20 g a day for 28 days.3
So for soreness, how many days you take BCAAs around a hard session may matter more than whether a dose lands just before or just after it, though the evidence comes from small trials and NIH still calls the recovery evidence inconsistent.3,4
During a workout
Some labels, ours included, list during training as an option. We did not find a trial that compared drinking BCAAs during a workout with before or after it. Blood levels peak about 30 minutes after a drink, so a dose early in a long session reaches the blood while you are still training.5
With meals or protein
A meal or shake with 25 g of complete protein already supplies about 10 g of essential amino acids, BCAAs included. Adding a BCAA drink to that meal adds little that the protein has not already provided.4
Studies give inconsistent evidence that BCAAs raise muscle protein building beyond what enough high-quality protein already does.4
A BCAA drink might fit best when you train without having eaten, but we found no trial that tested this against a protein meal.
Powder, capsules or tablets
Several of the trials we read gave BCAAs as a drink, and one six-month trial used five 1 g capsules a day. No trial we found compared powder with capsules or tablets, so the timing evidence is the same for all three.5,6,7
If you take levodopa
Timing matters most for people taking levodopa. Its label says amino acids compete with it for absorption and a high protein diet may reduce how much is absorbed. Ask your doctor or pharmacist before using BCAAs, and do not change your medicine schedule on your own.8
Questions people ask
Should I take BCAAs on rest days?
In several of the soreness trials, BCAAs were taken daily for days before and after the hard session, not only on the exercise day. No trial has tested rest-day use on its own.3
Can I take BCAAs on an empty stomach?
Yes, as far as studies show. In one trial, a BCAA drink taken on its own, with no food, peaked in the blood within 30 minutes. If you eat a protein-rich meal near training anyway, the extra BCAAs add little.4,5
What is the best time to take BCAAs for muscle growth?
There is no proven best time, and NIH says it is unclear whether timing around a workout changes how well protein or BCAAs build muscle. Getting enough complete protein through the day matters more.4
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Sources
- Ra SG, et al. 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;58(11):1582-1591. Opened 2026-10-07.
- Meng K. Effect of Timing of Branched-Chain Amino Acid Supplementation on Muscle Recovery after Resistance Training in Healthy Males. Am J Mens Health. 2025;19(2):15579883251332731. Opened 2026-10-07.
- Salem A, et al. 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. Sports Med Open. 2024;10(1):42. Opened 2026-10-01.
- National Institutes of Health, Office of Dietary Supplements. Dietary Supplements for Exercise and Athletic Performance: Fact Sheet for Health Professionals. Updated April 1, 2024. Opened 2026-10-07.
- Jackman SR, et al. Branched-Chain Amino Acid Ingestion Stimulates Muscle Myofibrillar Protein Synthesis following Resistance Exercise in Humans. Front Physiol. 2017;8:390. Opened 2026-10-01.
- Shimomura Y, et al. Branched-chain amino acid supplementation before squat exercise and delayed-onset muscle soreness. Int J Sport Nutr Exerc Metab. 2010;20(3):236-244. Opened 2026-10-07.
- Muscella A, Felline M, Marsigliante S. Sex-Based Effects of Branched-Chain Amino Acids on Strength Training Performance and Body Composition. Sports (Basel). 2024;12(10):275. Opened 2026-10-07.
- Sinemet (carbidopa and levodopa) tablets: prescribing information (Organon). DailyMed, U.S. National Library of Medicine. Published August 24, 2026. Opened 2026-10-07.
This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.