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 1 H-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.
Keywords: exercise metabolism; metabolomic; skeletal muscle; supramaximal effort.
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