BCAAs and Aerobic Exercise

In the previous post (BCAAs and Strength Training), we discussed whether BCAAs were effective in increasing strength. The same reasons BCAAs SHOULD increase strength are the same reasons they SHOULD increase aerobic performance. In this post, we’ll go over research specifically looking into BCAAs and aerobic exercise performance.

Research on BCAAs and Aerobic Exercise

Study 1: Effects of branched amino acids in endurance sports: a review1

The first article was a review which looked at 14 studies. Researchers wanted to know if BCAAs provided benefits to endurance sports (running, cycling, and Olympic triathlons). The studies measured the effects of BCAAs on muscle damage, athletic performance, central fatigue, anabolic response during recovery, and immune response.

The results showed there was a lesser degree of pain and muscle damage, decreased perceived exertion and mental fatigue, greater anabolic response during recovery, and an improved immune response in the groups taking BCAAs. Researchers however, did not find any evidence of improved performance.

Study 2: Branched-chain amino acid supplementation and resistance training maintains lean body mass during a caloric restricted diet2

This study looked at the effects of a calorie restricted diet on multiple measurements including muscular endurance. Seventeen participants were assigned to either a BCAA or carbohydrate group and were either given a pre and post workout BCAA supplement or a pre and post workout carbohydrate supplement. Each group got 14 grams of their respective supplement before and after working out for a total of 28 grams.

Subjects completed as many repetitions as possible at 80% of their maximum bench press and squat to measure endurance. The results were mixed. The carbohydrate group saw more improvement in endurance than the BCAA group. The carb group performed about 5 more repetitions on the squat while the BCAA group saw no change. Neither group saw a significant change in bench press repetitions.

Study 3: Effect of BCAA intake during endurance exercises on fatigue substances, muscle damage substances, and energy metabolism substances3

This study looked at the effects BCAA supplementation had on muscle damage resulting from endurance exercise. Twenty six participants were split into a supplement and control group. Both groups performed an endurance workout to exhaustion. Various measures of fatigue, muscle damage, and energy metabolism were recorded before, during, and after the workout.

Researchers measured three types of substances in this study: 1) fatigue substances (serotonin, ammonia, lactate), 2) muscle damage substances (creatine kinase, lactate dehydrogenase), and 3) energy metabolism substances (free fatty acids, glucose).

The researchers concluded that BCAAs could lower levels of serotonin (a chemical associated with fatigue), reduce muscle damage substances, and increase endurance exercise performance. They stated, “the intake of the BCAA is presumed to help contribute to enhancing exercise performance by exerting its influence on fatigue substances, muscle damage substances, and energy metabolism substances.”

Study 4: Branched-chain amino acid supplementation increases the lactate threshold during an incremental exercise test in trained individuals4

The final study examined the effects of BCAAs on the lactate threshold (the point at which lactic acid concentrations in the blood increases because it is produced at a faster rate than the body’s ability to remove it; performance decreases once an athlete reaches the lactate threshold5). Eight participants were split into two groups: BCAA and placebo. Both groups took their supplement (or placebo) for six days.

On the 7th day, participants performed a cycle ergometer test to measure their lactate threshold. The results showed the workload level in the BCAA group at the lactate threshold was higher than in the placebo group. The BCAA group also had a higher VO2 max. This indicates an increased aerobic capacity. Researchers concluded that BCAA supplements may an effective way to increase endurance performance.

The Bottom Line – Do BCAAs increase aerobic performance?

The evidence of BCAAs increasing aerobic performance is certainly much better than it was with strength training, but still far from extremely convincing. The results of the studies were mixed. The first study (which was a review of 14 other studies) showed some benefits including less pain during recovery, less mental fatigue, and an improved immune response. The researchers however, did not find any performance increase.

The second study was not promising. It showed the non-BCAA performed slightly better. This study however, compared BCAAs to carbohydrates, which somewhat limits its practical application. Not many people choose between taking either BCAAs OR carbohydrates, but instead mix them together.

The third study showed promising results and found BCAAs could enhance performance. The last study also showed positive results with researchers stating BCAAs could increase the lactate threshold, VO2 max, and increase endurance performance.

Current research indicates BCAAs have the potential to increase aerobic performance in certain populations, but again, the research is not conclusive and there are plenty of studies that disagree with their value.


  1. Salinas-García, M. E., & Martínez-Sanz, J. M. (2014). Effects of branched amino acids in endurance sports: A reviewNutricion Hospitalaria, 16(31), 2nd ser., 577-589. doi:10.3305/nh.2015.31.2.7852
  2. Dudgeon, W. D., & Kelley, E. P. (2016). In a single-blind, matched group design: Branched-chain amino acid supplementation and resistance training maintains lean body mass during a caloric restricted dietJournal of the International Society of Sports Nutrition, 13(1). doi:10.1186/s12970-015-0112-9
  3. Kim, D., & Kim, S. (2013). Effect of BCAA intake during endurance exercises on fatigue substances, muscle damage substances, and energy metabolism substancesJournal of Exercise Nutrition and Biochemistry, 17(4), 169-180. doi:10.5717/jenb.2013.17.4.169
  4. Matsumoto, K., & Koba, T. (2009). Branched-Chain Amino Acid Supplementation Increases the Lactate Threshold during an Incremental Exercise Test in Trained IndividualsJournal of Nutritional Science and Vitaminology, 55(1), 52-58. doi:10.3177/jnsv.55.52
  5. Lactate Threshold for Aerobic Performance. (n.d.). Retrieved from https://www.amc.edu/patient/services/SportsMedicine/lactate_threshold.cfm
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