No effect of short-term amino acid supplementation on variables related to skeletal muscle damage in 100 km ultra-runners – a randomized controlled trial

Journal Title (Medline/Pubmed accepted abbreviation): J. Int. Soc. Sports Nutr.
Year: 2011
Volume: 8
First page: 6

Summary of Background and Research Design

Background: Ultra-marathons are races that are at least 100 km and running this extremely long distance causes elevated markers of skeletal damage including creatine kinase, urea, and myoglobin. It has been shown in cyclists that ingestion of protein or amino acids can delay and reduce muscle soreness and increase overall performance.

Hypothesis: An amino acid supplementation before and during an ultra-marathon will attenuate muscle damage, as reported by perceived soreness and blood markers of muscle damage.

Experimental design: randomized interventional field study

Event and Subjects: Subjects were recruited from the 2009 “100 km Lauf Biel” in Biel, Switzerland. About 1,000 Caucasian males participated in the race, 28 participated in this study. The study participants were about 35-50 yrs old with varied experience in distance running (about 1-20 yrs).

Treatments: The amino acid supplement was in tablet form and included a blend of 14 amino acids. A placebo tablet was not used.

Protocol: Subjects were matched for personal bests in previous ultra-marathons and randomly assigned to the amino acid group or the control group. One hr before the race, the amino acid group consumed 12 amino acid tablets, and then they consumed 4 tablets at each of the 17 aid stations along the race. In the total duration of the race, they consumed 52.5 g of amino acids, including 20 g branched-chain amino acids. All participants recorded their training regimens leading up to the race and their nutritional and fluid intake during the race. Before and after the race, height, body mass, and percent body fat (using skin fold) were measured and a blood sample was acquired for analysis of creatine kinase, urea, and myoglobin. Only one athlete, in the control group, did not finish the race.

Summary of research findings
  • Those in the amino acid group finished in 624.3 ± 79.5 min and those who finished in the control group finished in 697.8 ± 89.7 min. When final race times were adjusted for personal best times there was no significant difference between the amino acid group and the control group.
  • Fluid intake, energy intake, and energy expenditure were all similar between groups, though those in the amino acid group consumed significantly more protein.
  • Those in the amino acid group lost 1.8 ± 1.6 kg and those in the control group lost 1.9 ± 2.0 kg (p > 0.05).
  • Creatine kinase, serum urea, and myoglobin all increased from pre-race to post-race for all the subjects with no differences between groups.
  • There was no difference in subjective feelings of muscle soreness between the 2 groups.

Interpretation of findings/Key practice applications

Amino acid supplementation at 52.5 g during an ultra-marathon did not increase performance, reduce muscle soreness, or attenuate blood markers of muscle damage.


This study was an acute study in which the amino acids were given only just before and during the race. It is not known if a longer period of amino acid supplementation would have had a benefit. In addition, muscle damage and soreness markers were only measured before and immediately after the race. It is possible that the amino acid supplementation effects might not have manifested until the athlete was well into the recovery period, but this possibility could not be evaluated given the study design. Finally, there was no true placebo control in this study, since the authors stated that they did not feel it would be safe to give the high-calcium placebo during the race when subjects were dehydrated. It is not clear why a different placebo was not chosen or if this lack of a placebo would have had any effects on the study outcomes.
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