Omega-3 index and AA/EPA ratio as biomarkers of running-related injuries: An observational study in recreational runners.

The aim of this study was to examine the association between biomarkers of polyunsaturated fatty acids (PUFA), such as omega-3 (ω-3) index and arachidonic acid (AA; 20:4 ω-6)/eicosapentaenoic acid (EPA; 20:5ω-3) ratio (AA/EPA), and the prevalence of running-related injuries (RRI) in a cohort of recreational runners. We performed a retrospective, observational study of 275 non-elite runners (mean age: 41.20 ± 12.47 years) who were not supplemented with ω-3 fatty acids. The training characteristics and RRI were recorded over a period of 12 months through a self-reported questionnaire. Using whole blood samples collected by finger prick, PUFA were quantified by gas chromatography and ω-3 index and AA/EPA ratio measured. A total of 191 RRI cases were reported, with an injury prevalence rate of 50.9% in the overall population. The injured runners ran a significantly greater weekly distance than uninjured subjects (53.54 ± 25.27 km/week;  = 0.007). In a multivariate regression analysis, the lowest number of RRI was associated with higher values of ω-3 index ( = - 0.237; 95% CI - 0.308 to - 0.164;  = 0.172;  < 0.0001), while a higher AA/EPA ratio was correlated with higher number of RRI ( = 0.019; 95% CI 0.007-0.031;  = 0.038;  = 0.003). This study identifies ω-3 index and AA/EPA ratio as potential parameters associated with the risk of RRI. Future research is needed to confirm these results and apply specific nutritional strategies to successfully modify these biochemical variables. ISRCTN.org identifier: ISRCTN12847156..