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The study aimed to identify and quantify the metabolites profile and metabolic pathways in human muscle tissue engaged during exhaustive high‐intensity cycling exercise. Seven healthy physically active men performed a graded exercise test and an exhaustive supramaximal effort at 115% of maximal aerobic power with muscles biopsies performed in rest and immediately after exhaustion for quantifying of muscle metabolites changes by 1H‐NMR spectroscopy. The time until exhaustion (tlim) recorded was 224.7 ± 35.5 s whereas the muscle pH at exhaustion was 6.48 ± 0.05. A total of 54 metabolites were identified and quantified. The most enriched and impacted pathways included: beta oxidation of very long chain fatty acids, mitochondrial electron transport chain, alanine aspartate, and glutamate metabolism, citric acid cycle, arginine biosynthesis, propanoate metabolism, threonine and 2‐oxobutanoate degradation and pyruvate metabolism. In addition, the muscle concentrations in Post exercise, compared to Pre increased significantly (p < 0.0398) for fumarate (42.0%), succinate (101.2%), glucose (249.7%), lactate (122.8%), O‐acetylcarnitine (164.7%), glycerol (79.3%), AMP (288.2%), 2‐oxobutyrate (121.0%), and methanol (58.5%), whereas decreased significantly (p < 0.010) for creatine phosphate (−70.2%), ADP (−56.5%), carnitine (−33.5%), and glutamate (−42.3%). Only the succinate was significantly correlated with tlim (r = −0.76; p = 0.0497). Besides the classical expected contribution of glycolytic and phosphagen energetic pathways, it was demonstrated that the high‐intensity exercise is also associated with pathways indicatives of amino acid and fatty acid oxidation metabolisms, highlighting the inverse relation between changes in the intramuscular succinate levels and tlim. [ABSTRACT FROM AUTHOR]

PURPOSE: To analysis the effect of cycling exercise at acute severe intensity domain on modulation of metabolomic profile in human muscle tissue, as well as to report the main metabolic pathways. METHODS: Seven healthy physically active men (21±2 yrs and VO2max of 43.6±4.6 mL·kg-1·min-1) were underwent to an effort until exhaustion at severe intensity domain. Vastus lateralis muscle biopsies were performed before (at rest) and immediately after the effort for quantifying the muscle metabolites changes using ¹H-NMR spectroscopy. RESULTS: The time until exhaustion (tlim) recorded was 224.7±35.5 s, whereas the energetic contribution corresponded to 71.2±2.8% oxidative, 20.0±3.0% glycolytic and 8.8±1.3% phosphagen. The muscle pH after cycling exhaustion was 6.48±0.05. A total of 54 metabolites were identified and quantified. The most impacted pathways (impact > 0.0) included: beta oxidation of very long chain fatty acids (0.049), mitochondrial electron transport chain (0.060), alanine aspartate and glutamate metabolism (0.200), citric acid cycle (0.118), arginine biosynthesis (0.117), propanoate metabolism (0.004), threonine and 2-oxobutanoate degradation (0.143) and pyruvate metabolism (0.084). The muscle metabolite concentrations Pre and Post exercise increased for fumarate (42%, p=.025), succinate (101%, p=.021), glucose (245%, p=.001), lactate (123%, p=.004), O-acetylcarnitine (165%, p=.011), glycerol (79%, p=.040), AMP (288%, p=.008), 2-oxobutyrate (121%, p<.001) and methanol (58%, p=.034). There were decreases for creatine phosphate (-70%, p=.008), ADP (-56%, p=.007), carnitine (-33%, p=.006) and glutamate (-42%, p=.009). However, only the succinate had a significantly correlation with tlim (r=-0.76, p=.0497). In addition, the muscle pH measured at exhaustion was significantly correlated with tlim (r=-0.83; p=.042), the post-exercise succinate concentration (r=0.93; p=.006). CONCLUSIONS: Besides the classical expected contribution of glycolytic and phosphagen energetic pathways, the high-intensity exercise was associated with pathways indicatives of amino acid and fatty acid oxidation metabolisms, highlighting the inverse correlation between intramuscular succinate levels and tlim. Supported by FAPESP Grant 2018/21126-6 [ABSTRACT FROM AUTHOR]