AUTHOR=Davinelli Sergio , Corbi Graziamaria , Righetti Stefano , Casiraghi Elena , Chiappero Francesco , Martegani Serena , Pina Riccardo , De Vivo Immaculata , Simopoulos Artemis P. , Scapagnini Giovanni 

TITLE=Relationship Between Distance Run Per Week, Omega-3 Index, and Arachidonic Acid (AA)/Eicosapentaenoic Acid (EPA) Ratio: An Observational Retrospective Study in Non-elite Runners

JOURNAL=Frontiers in Physiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2019.00487

DOI=10.3389/fphys.2019.00487

ISSN=1664-042X

ABSTRACT=<p><bold>Background:</bold> Tissue availability of polyunsaturated fatty acids (PUFA) depends on several factors, including dietary intake, physical exercise, genetic variation, and metabolic turnover. However, there is limited evidence whether running training activity <italic>per se</italic> may influence indices associated with PUFA metabolism such as Omega-3 (ω-3) index and arachidonic acid (AA; 20:4ω-6)/eicosapentaenoic acid (EPA; 20:5ω-3) ratio.</p><p><bold>Objective:</bold> To examine the association between kilometers (Km) run per week and changes in ω-3 index and AA/EPA ratio.</p><p><bold>Methods:</bold> We conducted a retrospective, observational, cohort study of 257 non-elite runners (mean age: 40.85 ± 12.17 years) who consumed no fatty acid supplements and provided a blood sample for analysis. The whole blood samples were collected by finger sticks, stored on absorbent filter paper, and then PUFA were quantified by gas chromatography (GC) and ω-3 index and AA/EPA ratio measured.</p><p><bold>Results:</bold> In a multivariate linear regression model, a gradual decrease of the ω-3 index was observed with higher weekly running distance (β = −0.033; 95% CI −0.039 to −0.026; R<sup>2</sup> = 0.447; <italic>p</italic> &lt; 0.0001). We also found a progressive increase of the AA/EPA ratio in subjects who ran greater weekly distances (β = 0.092; 95% CI 0.038 to 0.146; R<sup>2</sup> = 0.320; <italic>p</italic> = 0.001). No other significant associations were observed with other variables, including years of running training and weekly training frequency (hours/week). Finally, as expected, a significant inverse correlation between ω-3 index and AA/EPA ratio (β = −2.614; 95% CI −3.407 to −1.821; R<sup>2</sup> = 0.336; <italic>p</italic> &lt; 0.0001) was detected.</p><p><bold>Conclusions:</bold> These findings suggest that distance running training and its weekly volume may negatively contribute to changes of the ω-3 index and AA/EPA ratio. Further studies with greater sample size will be required to replicate and extend these data.</p>