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. 2015 Sep 15;10(9):e0138376.
doi: 10.1371/journal.pone.0138376. eCollection 2015.

Changes in Serum Free Amino Acids and Muscle Fatigue Experienced During a Half-Ironman Triathlon

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Free PMC article

Changes in Serum Free Amino Acids and Muscle Fatigue Experienced During a Half-Ironman Triathlon

Francisco Areces et al. PLoS One. .
Free PMC article

Abstract

The aim of this study was to investigate the relationship between changes in serum free amino acids, muscle fatigue and exercise-induced muscle damage during a half-ironman triathlon. Twenty-six experienced triathletes (age = 37.0 ± 6.8 yr; experience = 7.4 ± 3.0 yr) competed in a real half-ironman triathlon in which sector times and total race time were measured by means of chip timing. Before and after the race, a countermovement jump and a maximal isometric force test were performed, and blood samples were withdrawn to measure serum free amino acids concentrations, and serum creatine kinase levels as a blood marker of muscle damage. Total race time was 320 ± 37 min and jump height (-16.3 ± 15.2%, P < 0.001) and isometric force (-14.9 ± 9.8%; P = 0.007) were significantly reduced after the race in all participants. After the race, the serum concentration of creatine kinase increased by 368 ± 187% (P < 0.001). In contrast, the serum concentrations of essential (-27.1 ± 13.0%; P < 0.001) and non-essential amino acids (-24.4 ± 13.1%; P < 0.001) were significantly reduced after the race. The tryptophan/BCAA ratio increased by 42.7 ± 12.7% after the race. Pre-to-post changes in serum free amino acids did not correlate with muscle performance variables or post-race creatine kinase concentration. In summary, during a half-ironman triathlon, serum amino acids concentrations were reduced by > 20%. However, neither the changes in serum free amino acids nor the tryptophan/BCAA ratio were related muscle fatigue or muscle damage during the race.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. A) Relationship between race time and sector times (swimming, cycling and running) and post-race tryptophan/BCAA ratio during a half-ironman race. B) Relationship between post-race creatine kinase concentration and changes of BCAA concentration during a half-ironman race (as a change from pre-exercise values).
Note: A) The correlation of total race time (r = -0.05; P = 0.80), swimming time (r = -0.05; P = 0.80), cycling time (r = 0.08; P = 0.70) and running time (r = -0.21; P = 0.30) with post-race tryptophan/BCAA ratio were not statistically significant. B) The correlation of post-race creatine kinase concentration with BCAA change during the race (r = -0.02; P = 0.92) was not statistically significant.

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Grant support

These authors have no support or funding to report.
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