While many athletes have different preferences for when to take amino acids, evidence from several studies suggests that the best time to take amino acids is directly before a workout. This timing seems to best trigger muscle synthesis, prevent muscle damage and stimulate recovery, as well as decreasing fatigue and suppressing symptoms of delayed onset muscle soreness (DOMS).

A popular amino acid complex to take before a workout are BCAAs, or branched-chain amino acids. BCAAs include three essential amino acids—leucine, isoleucine, and valine. They are called essential amino acids because they cannot be produced or synthesized by the body, but are important for normal bodily function. BCAAs in particular make up nearly 35% of the amino acids present in muscle tissue.

While BCAAs are present in food and protein supplements, they can sometimes take too long to process to achieve full benefits during a workout. That’s why taking BCAAs 30 minutes prior to a workout is usually preferred by athletes.

4 Reasons to Take Amino Acids Before a Workout

1 – Helps Prevent Fatigue

In a study published in the Journal of Nutrition in January 2006, researchers found that the oral intake of BCAAs prior to a workout may increase an uptake in essential amino acid tryptophan and reduce the synthesis and release of serotonin, which may delay fatigue during a longer or harder workout.[1]

Another reason these BCAAs may reduce fatigue is because during a workout, your body breaks down BCAAs to use as an energy source. If you’re planning on a more intense or longer workout, taking a BCAA supplement beforehand will prime you with more BCAAs to be able to train more intensely and for a longer period of time.[2]

2 – Stimulates Muscle Synthesis

During a workout, both your muscle breakdown and muscle synthesis systems are activated. Post-workout, your muscle breakdown exceeds muscle synthesis until the essential amino acid leucine is ingested. This is because leucine activates mTOR which stimulates protein synthesis and muscle tissue growth.[3]

When you already have an increase of BCAAs in your body from taking amino acids prior to your workout, leucine is primed and ready to help your muscles rebuild and recover post-workout.

Some people think this means that you should take your BCAAs directly after the workout, but a study by the Department of Surgery, University of Texas Medical Branch, showed as much as a 2.5X increase in phenylalanine uptake when an oral essential amino acid-carbohydrate supplement was taken pre-workout as opposed to post-workout. The study suggested that net protein synthesis is greater when amino acids were consumed before exercise compared to after a workout.[4]

3 – Decreases Delayed Onset Muscle Soreness (DOMS)

While extensive studies have not yet been performed, early tests suggest that taking amino acids before a workout can decrease the symptoms of delayed onset muscle soreness (DOMS) as much as 20%. In this double-blind study, 12 young, healthy, untrained female participants ingested either BCAA or a placebo prior to a squat exercise. Two days after the exercise, the BCAA trial reported significantly less soreness than the placebo trial. This study also suggested that BCAAs may suppress muscle damage.[5]

4 – Prevents Muscle Damage

In multiple tests, results suggested that taking BCAAs prior to a workout may reduce muscle damage. During these studies, participants showed a decrease in serum concentrations of creatine kinase (KS) and lactate dehydrogenase (LDH) which have been shown to be accurate indicators of muscle damage. These studies showed that even when the recommended intake of BCAA was already present in regular diet, taking BCAAs prior to the workout significantly decreased the post-exercise values of these enzymes, suggesting decreased muscle damage.[6]

Final Thoughts

While there are still several studies that can—and likely will—be done on the fascinating science of amino acids, the early research suggests that taking amino acids 30-60 minutes prior to a workout can significantly increase their benefits.

Remember to always consult a qualified healthcare professional prior to beginning any diet or exercise program and before beginning any dietary supplement. This article is not intended to diagnose or serve as medical advice; it is only intended to provide informational resources.


[1] Newsholme, E. A., Acworth, I. N., & Blomstrand, E. (1987). Amino acids, brain neurotransmitters and a functional link between muscle and brain that is important in sustained exerciseAdvances in Myochemistry, 1, 127-133.

[2] Gomez-Merino, D., Bequet, F., Berthelot, M., Riverain, S., Chennaoui, M., & Guezennec, C. Y. (2001). Evidence that the branched-chain amino acid L-valine prevents exercise-induced release of 5-HT in rat hippocampus.

[3] Wang, X., & Proud, C. G. (2006). The mTOR pathway in the control of protein synthesisPhysiology, 21(5), 362-369.

[4] Tipton, K. D., Rasmussen, B. B., Miller, S. L., Wolf, S. E., Owens-Stovall, S. K., Petrini, B. E., & Wolfe, R. R. (2001). Timing of amino acid-carbohydrate ingestion alters anabolic response of muscle to resistance exerciseAmerican Journal of Physiology-Endocrinology And Metabolism, 281(2), E197-E206.

[5] Shimomura, Y., Inaguma, A., Watanabe, S., Yamamoto, Y., Muramatsu, Y., Bajotto, G., … & Mawatari, K. (2010). Branched-chain amino acid supplementation before squat exercise and delayed-onset muscle sorenessInternational Journal of Sport Nutrition, 20(3), 236.

[6] Coombes, J. S., & McNaughton, L. S. (2000). Effects of branched-chain amino acid supplementation on serum creatine kinase and lactate dehydrogenase after prolonged exerciseJournal of Sports Medicine and Physical Fitness, 40(3), 240.