Metabolomics reveals that fittest trail runners show a better adaptation of bioenergetic pathways

To analyze the effect in the blood metabolome of trail running, a demanding sport that takes place in the natural environment, places considerable strain on both muscles and joints. While metabolic responses to aerobic exercise have been analyzed in-depth, few studies have focused on trail running.

Observational study to analyze changes in 35 different metabolites - representative of aerobic exercise-induced by a simulated 21-km trail race with an uphill gradient of 1400 m.

We performed a semiquantitative metabolomics study consisting of capillary blood microsampling and targeted screening with liquid chromatography and mass spectrometry to analyze, in 33 licensed athletes, changes concerning 35 metabolites.

We observed significant changes in many metabolites, including increased acetyl-carnitine and taurine concentrations (false discovery rate-corrected paired t-test P value 1.63 × 10^-13, and P value 5.021 × 10^-12, respectively) and decreased carnitine and proline concentrations (P value 6.33 × 10^-10, and P value 1.21 × 10^-9, respectively). Metabolic responses to trail running were largely independent of sex but were influenced by the level of training, with runners with a higher level showing resistance to exercise-induced changes in taurine, 1-methyl histidine, acetyl-carnitine, and hypoxanthine concentrations. Performance (measured as race time) was inversely correlated with changes in specific metabolites (including taurine, serotonin, and hypoxanthine) and directly correlated with increases in glutathione.

Our findings demonstrate the usefulness of metabolomics studies for analyzing exercise-induced physiological changes and show individual differences associated with the level of training and performance.