Differences in intrinsic aerobic capacity play a critical role in the development of perturbed metabolism, chronic disease and all‐cause mortality. Aims were to employ metabolomics to examine differences in age vs. aerobic capacity in young and old rats selectively bred for low (LCR) or high (HCR) aerobic capacity. Proton nuclear magnetic resonance spectroscopy (1H‐NMR) evaluated the metabolic profile of plasma samples obtained from fasted LCR and HCR. Multivariate statistical analysis was employed, with individual features judged based on variability R2 and predictive ability Q2 in unsupervised and supervised models built using the most significant metabolites. Taurine, pyruvate, acetone, valine, amongst others were key metabolites that contributed to distinct separation based on age (R2=0.83, Q2=0.65). In contrast, weaker predictive models were observed for LCR vs. HCR with scores of R2=0.53 and Q2=0.35 respectively. Key metabolites that decreased in HCR compared to LCR included isopropanol, o‐acetylcarnithine, sarcosine and proline. Pathway analysis highlighted changes in methionine, purine and TCA cycle intermediates. In conclusion, metabolomics analysis was a better predictor and age rather than aerobic capacity in LCR and HCR rats. This observation highlights the importance of age when attempting to isolate metabolic changes in aerobic capacity and their relation to chronic disease risk.Grant Funding Source: Supported by the Alberta Cancer Foundation