[Effects of muscle fatigue on urine metabolites in automobile manufacturing workers based on untargeted metabolomics]

Objective: To investigate the changes of metabolites in urine of automobile manufacturing workers with muscle fatigue using metabolomics technology, and to explore potential biomarkers and disrupted metabolic pathways. Methods: In July 2022, urine samples were collected from 35 male workers in a certain automobile manufacturing industry before and after muscle fatigue, and metabolite analysis was conducted. Subsequently, multivariate statistical analysis was used for data processing to screen differential metabolites. Metabolic pathway enrichment was performed using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database (http: //www.kegg.jp), and potential biomarkers were screened through the receiver operating characteristic (ROC) curve. Results: Metabolomics analysis revealed that compared to pre-fatigue samples, a total of 363 differential metabolites were identified in the post-fatigue urine samples of the subjects. Among these, 201 metabolites (55.4%) showed increased relative expression, while 162 metabolites (44.6%) showed decreased relative expression. The metabolic pathways involved mainly included histidine metabolism, tryptophan metabolism, valine, leucine and isoleucine biosynthesis, caffeine metabolism, niacin and nicotinamide metabolism, and oxidative phosphorylation. The ROC curve analysis results showed that the areas under the ROC curves for 1-methylnicotinamide, 2-piperidinone, kojic acid and diferuloyl Putrescine were 0.992, 0.959, 0.937 and 0.902, respectively. Conclusion: Muscle fatigue could cause changes in urine metabolite profiles of automobile manufacturing workers. The metabolites represented by 1-methylnicotinamide in urine can be used as potential biomarkers of muscle fatigue in automobile manufacturing workers.