Plasma Metabolome and Metabolite Toxicity Profiling of Moderate-Intensity Running in Human Females

Background: Existing exercise metabolomics studies have predominantly focused on changes in the type and abundance of metabolites, while rarely addressing the toxicity risk of differential metabolites. Metabolic toxicity refers to the potential of endogenous or exogenous metabolites to induce oxidative stress, cell death, and other forms of biological damage when excessively accumulated and serves as a key driver of metabolic disorders. This study aims to characterize the toxicity risk of plasma differential metabolites before and after a single session of moderate-intensity running, so as to investigate the exercise-induced changes in metabolic toxicity. Methods: A single-group self-pretest–posttest control design was adopted in this study. Participants were recruited from Wuhan Sports University, China, with the inclusion criteria of healthy females aged 22–30 years and BMI 18.5–24.9. Individuals with a history of metabolic diseases or who met other exclusion criteria were excluded, and 5 females were finally enrolled. The exercise protocol consisted of a single 40 min session of moderate-intensity running on a treadmill. We collected plasma samples from five healthy females before and after exercise and performed untargeted LC-MS/MS metabolomic profiling. The gap-Δenergy algorithm was applied to calculate the toxicity scores of differential metabolites, and the proportion of metabolites with high toxic potential (score > 0.6) was compared. Results: Plasma metabolic profiles underwent notable remodeling after exercise. Thirty-two metabolites were upregulated and the phosphosphingolipid SM(d18:2(4E,14Z)/16:0) was the most significant. Meanwhile 32 metabolites were downregulated and the phosphosphingolipid PC(18:1(9Z)/14:0) was the most significant. The 64 differential metabolites were enriched in 9 KEGG pathways including amino acid metabolism and lipid metabolism. Moreover, we systematically evaluated the toxicity of these metabolites using the gap-Δenergy algorithm and found that the downregulated metabolites exhibited a significantly higher toxicity score compared to the upregulated ones. In addition, 37.5% of the downregulated metabolites had a high toxicity score, while the proportion of high toxicity in the upregulated group was only 15.6%. Conclusions: This study demonstrates that moderate-intensity running may confer metabolic health benefits to individuals by reducing metabolic toxicity, specifically through the downregulation of metabolites with high toxic potential. These findings offer novel evidence for exercise’s role in improving metabolic health. They also open a new direction for exercise-based interventions in metabolic disease–toxicity regulation.