Abstract Body (Do not enter title and authors here): Introduction: Exercise training is known to improve cardiovascular risk, to increase HDL cholesterol (HDL-C) levels and HDL functionality, by improvement of cholesterol uptake by HDL, and decreases the potential atherosclerotic of low-density lipoprotein (LDL) particles. Marathon running is presumed to have the same effects, however health benefits of high volume running in dyslipidemic marathon runners are unknown.
Aims: Using marathon runners as models for intense exercise training, this study aimed to evaluate differences in HDL composition, function and vascular reactivity between marathons runners with and without dyslipidemia, comparing with sedentary controls.
Methods: 20 marathon runners with and 13 without dyslipidemia, 17 sedentary individuals with and 12 without dyslipidemia were enrolled. In all individuals, plasma lipids and apolipoproteins (apo) were measured by commercial kits and HDL size by laser light scattering method. Paraoxonase 1 (PON1) activity using commercial kits and vascular reactivity were evaluated. Lipid transfer was performed by incubating plasma with a lipid donor nanoemulsion containing radioactively labeled non-esterified cholesterol (NEC) and esterified cholesterol (EC), followed by chemical precipitation and radioactive count. We also performed an assay that analyses the cholesterol transfer to HDL from TGRL upon lipolysis.
Results: All individuals were male, with no age difference between groups (42 to 47 years). Marathon runners without dyslipidemia were thinner than the other groups. While HDL-C concentrations and apo A1 levels were higher in runners, LDL-C and apo B levels were higher in dyslipidemic groups. Regarding PON1 and vascular reactivity, no statistical differences were observed. We observed greater transfer of EC and NEC in the marathon runners compared to sedentary individuals (p 0.015), with no difference between marathon runners with and without dyslipidemia. Important correlations were observed between Apo A1 and all transfers: both NEC and EC, and also cholesterol transfer to HDL from triglyceride-rich lipoprotein (TGRL) upon lipolysis (p < 0.001, <0.001 and 0.011, respectively). Additionally, we observed correlation between ApoA1 and vascular reactivity (p=0.032).
Conclusion: Marathon runners have higher levels of HDL-C and apo A1. They have a better ability to cholesterol transfer to HDL and this functionality remains despite being dyslipidemic, with increased levels of LDL-c and apo B.