Branched-chain amino acid supplementation during a 100-km ultra-marathon- A randomized controlled trial

Journal Title (Medline/Pubmed accepted abbreviation):J. Nutr. Sci. Vitaminol.
Year: 2012
Volume: 58
Page numbers : 36-44

Summary of background and Research Design

Background: Ultra-marathon races are extremely hard on the body, even in the fittest athletes.  The runs can damage skeletal muscle and potentially impair renal function because of the excess products of muscle damage that the kidney is filtering.  Branched chain amino acids (BCAAs) have been shown to reduce the extent of muscle damage during exercise.

Hypothesis: Supplementation with BCAAs before and during a 100 km (62 mile) foot race will decrease the signs of muscle damage and the symptoms of kidney dysfunction.

Subjects: Twenty-seven males, age approximately 30-50 y, finished the race

Experimental design: randomized into one of the two groups

Treatments : BCAA: 50 g of amino acids (of which 20 g were BCAA) divided into 80 tablets- 12 tablets at the start and then 4 tablets at all of the 17 stations along the course.
Control group: no supplements were taken

Protocol : On race day, the participants were first assessed for height, weight, and percent body fat (as assessed with skin calipers).  Urine and blood samples were also acquired.  They began the race at 10:00pm, and ran overnight into the next day.  In addition to the biological samples, the participants provided responses to questionnaires immediately after the race regarding muscle soreness and how their performance met their expectations.

Summary of Research Findings
  • Those in the BCAA group finished the race in 624.3 ± 79.5 min whereas those in the control group finished in 697.8 ± 89.7 min.  (p = 0.033). However, these results are not statistically significant when adjusting for personal best time.
  • Muscle soreness was not alleviated by BCAA supplementation.
  • In blood, there were no differences in hematocrit, hemoglobin, sodium, potassium, albumin, and total protein between groups. Creatine kinase, serum urea, and myoglobin increased in all participants in response to the race with no differences between groups.
  • When assessing characteristics of urine and implied renal function, there were not differences between groups.

Key practice applications

Supplementation with BCAA before and during the ultra-marathon event (50 g amino acids in total) did not attenuate muscle damage or aid in the maintenance of kidney function.


There were several parameters in this study that were not assessed that may have helped control the study.  First of all, there was no placebo supplement.  Placebos are helpful because they place the athletes in the same psychological state, removing bias associated with greater mental expectation of results caused by just giving a pill itself.  Second, the athletes’ diet the day the race started was not analyzed.  This would help the authors calculate the total amount of amino acids ingested before the race to see if there were any confounding factors of the study results.   Finally, the authors probably did not allow enough time to elapse after the race to truly quantify if the BCAAs had a significant effect on delayed onset muscle soreness, since they only measured muscle soreness immediately after the race.
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