BCAAs For Runners Guide: 6 Potential Benefits, Risks + Efficacy

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The world of sports nutrition and performance supplements for runners is increasingly complex. The more we learn about nutrition and energy metabolism before, during, and after exercise, the more stocked the supplement store shelves become.

Most runners are well versed in the importance of protein for recovery, but protein supplements for runners now go beyond the basic protein powders and protein bars we’ve seen for years. 

Various amino acid supplements, and more specifically BCAA for runners, are now gaining significant traction in the sports nutrition, fueling, and supplementation routines of runners of all levels. 

In this guide, we will cover all the need-to-know information about BCAA for runners to help you decide whether they may be beneficial to your running performance and overall health.

We will cover the following: 

  • What is BCAA?
  • Sources of BCAA for Runners
  • Functions of BCAA for Runners
  • BCAA Benefits for Runners
  • Potential Risks of BCAA for Runners
  • When to Take BCAA for Runners, BCAA Before Running? Is BCAA Good For Recovery?
  • Should Runners Take BCAA?

Let’s get started! 

Bcaa for runners, a vile of powder with valine, leucine and isoleucine.

What Is BCAA?

Before we get into the specifics of BCAA, it’s helpful to review some basics from high school biology class. 

Our bodies break down all proteins found in food into 20 different amino acids, whether the protein comes from meat, beans, dairy, eggs, fish, or vegetables. These amino acids are considered the building blocks of protein, meaning that our bodies use amino acids to manufacture all the various structural and functional proteins in the body. 

Much like letters in the alphabet, by stringing together different combinations of these amino acid “letters,” our bodies are able to make the hundreds of different combinations of amino acids that constitute the wide variety of proteins we need to function. 

While we often just think of proteins forming structures like our muscles, they are involved in nearly every structure and function of the body in some way, from forming DNA to producing energy, to creating neurotransmitters to fueling white blood cells.

Of the 20 amino acids our body needs, nine must be consumed in the diet or in supplement form because our body cannot manufacture them. These are appropriately called essential amino acids (EAAs). 

Amino acid supplementation often focuses on these essential amino acids, or more specifically on three specific essential amino acids (leucine, isoleucine, and valine), referred to as branched-chain amino acids (BCAAs), due to their chemical structure. About one-third of your muscle protein is composed of BCAAs. 

A small chalkboard with amino acids written on it surrounded by foods high in protein.

Sources of BCAA for Runners

The discussion of BCAA for runners usually centers around BCAA supplements (powders, capsules, drink mixes, etc.), but BCAA should also be consumed through the diet. 

BCAA can be found in foods high in protein, particularly animal sources, such as meat, fish, poultry, eggs, milk, yogurt, and cottage cheese. Some plant-based foods, such as tofu, beans, lentils, tempeh, and seeds, also contain decent concentrations of BCAA. 

Functions of BCAA for Runners

BCAA supplements are particularly popular among athletes due to the fact that BCAAs have been shown to be the amino acids most directly involved in muscle protein synthesis, with research indicating that BCAAs help maintain muscle mass. 

Research suggests that of the three BCAAs, leucine is the amino acid that’s primarily responsible for stimulating muscle protein synthesis and preventing muscle breakdown, which is why supplementation of BCAA after running is particularly common. Most BCAA supplements for runners and other athletes contain twice as much leucine as isoleucine or valine, such that these three amino acids are in a 2:1:1 ratio.

Supplementation of BCAA before running is also popular due to the fact that the unique chemical structure of BCAA allows them to be rapidly metabolized through a more simple digestion process than most amino acids and proteins.

BCAAs have also been found to play critical roles in cell signaling, regulating the metabolism of glucose and lipids, synthesizing proteins, enhancing gut health, and supporting immunity.

Two men in a supplement store reading the label of a protein powder container.

BCAA Benefits for Runners 

There is quite an extensive body of research demonstrating exercise and performance benefits of BCAA for runners and other athletes. Some of the potential benefits of BCAA for runners include the following: 

#1: BCAA Support Muscle Growth and Strength Gains

Perhaps the primary reason athletes turn to BCAA is for the well-established role of BCAA in stimulating your body’s anabolic (muscle building) hormones to boost muscle protein synthesis. BCAA can help runners preserve muscle mass and build and repair new muscle fibers after training. 

According to one study involving patients with sarcopenia (muscle loss) due to liver cirrhosis, supplementation with BCAA led to a significant improvement in muscle strength, muscle function, and muscle mass. 

A woman doing a sit-up in a gym.

#2: BCAA Can Reduce Perceived Exertion and Time to Fatigue

Distance running is all about delaying fatigue and hanging on as long as you can without slowing down. Therefore, any supplement that can either increase your stamina or make you feel less tired has the ability to improve your overall performance. 

Several studies show BCAA can reduce the level of perceived exertion, helping runners feel like their same effort was less exhausting. 

Moreover, studies indicate a physiological component to this fatigue resistance, as BCAA can help preserve glycogen stores during endurance exercise, increasing the time to exhaustion. BCAA can also decrease lactate production, which can make your legs feel heavy and tired when you run.

#3: BCAA Can Inhibit Cortisol Production

According to research, BCAA can inhibit the deleterious effects of the stress hormone cortisol, which can increase in response to intense exercise, and when left unchecked, can contribute to muscle breakdown.   

Cortisol can also increase fat storage in the body, so keeping levels low can potentially prevent unintended weight gain.

A scoop of white powder.

#4: BCAA Can Reduce Post-Workout Soreness

We’ve all been sore after a workout, and while mild soreness is usually no big deal, muscle soreness can potentially compromise how hard you can train in subsequent days. 

Evidence demonstrates that BCAA after exercise can reduce the severity of delayed onset muscle soreness (DOMS) and muscle damage, expediting recovery from hard runs and tough workouts.

#5: BCAA Can Provide a Boost of Energy

Although protein isn’t one of the primary macronutrients oxidized for energy during exercise, BCAA can also be metabolized for energy during activity rather quickly due to their chemical structure.

While most amino acids must be metabolized in the liver, BCAAs are transported directly to the muscles and oxidized there and are said to contribute up to 10% of the total energy needs during running or other endurance exercises.

Therefore, a pre-workout drink with BCAA or BCAA ingested during a run can add to the pool of readily-available fuel for your body and spare some of the carbohydrates to delay bonking.

A runner hunched over from exhaustion.

#6: BCAA Can Improve Gut Health and Digestion

All runners need a healthy gut, both to prevent dodging off the racecourse to the nearest port-a-potty and to digest and absorb nutrients and keep a robust immune system.

There are also numerous animal studies demonstrating the gut benefits of BCAA. For example, BCAAs improve gut health by transporting nutrients, upregulating immune cells and signaling pathways, promoting intestinal development, and maintaining the integrity of the gut barrier.

There is also evidence to suggest that BCAA can cause favorable shifts in the composition of the gut microbiota, and have been found to improve cases of metabolic disorders and insulin resistance by reversing the harmful effects of high-fat diets, inhibiting inflammatory pathways, and strengthening the mucosal barrier. 

Most of these studies have also found that BCAA supplementation improves intestinal absorption of nutrients, which is important for runners because nutrition is key to injury prevention and recovery. 

A container full of white pills and a BCAA sign.

Potential Risks of BCAA

BCAAs are generally considered safe for all runners, particularly when just consumed in natural food sources. BCAA supplements for runners are also usually safe, provided you buy a high-quality supplement with no additional fillers, chemicals, or stimulants. 

In high doses, BCAA can cause nausea, diarrhea, headaches, dizziness, and lack of coordination. At very high doses, insulin resistance and kidney failure can result. Consult your physician for specific dosage recommendations.

When to Take BCAA for Runners

Given the potential benefits of BCAA for runners, a case can be made to take them before or after a workout.

BCAA before running or during your workout may increase energy, provide usable energy since they are metabolized right in the muscle, decrease ratings of perceived exertion, and increase time to exhaustion.

Is BCAA good for recovery? Yes. BCAA taken after a run can promote recovery, decrease cortisol levels, stimulate muscle protein synthesis and inhibit muscle protein breakdown, and reduce muscle soreness.

A woman outside in the evening getting ready to sprint.

Should Runners Take BCAA?

The decision to take BCAA is entirely up to you and should be made in the context of considering your overall diet and health needs. Older runners (subject to sarcopenia) and vegan or vegetarian runners may have the most to gain from BCAA, but your individual circumstances might make them more or less appropriate.

In addition to protein and amino acids, runners should make an effort to achieve overall healthy nutrition to reach peak performance and optimal health. Check out our Running Nutrition Guide to get on the path to a healthier you!

A spread of a healthy diet including chicken, meat, fruits, vegetables, and healthy fats.
Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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