Exhaustive treadmill run increases urinary excretion of albumin and creatinine but not cell-free DNA in average trained healthy men

Exercise induces a transient rise of NETotic cell-free DNA (cfDNA) in plasma. Various mechanisms may be responsible for temporary character of this phenomenon including cfDNA degradation by DNAse or uptake by vascular endothelium. We tested whether urinary excretion of cfDNA may contribute to its normalization in plasma after exercise. The study involved 15 average trained men (VO 2 max 45.5 ± 6.25 ml/kg x min) without urogenital pathology and had comparative and crossover design (exhaustive treadmill run, speed corresponding to 70% of VO 2 max, run distance 11.2 ± 4.7 km, run time 67 ± 19 min vs. 1.0 h rest). Exercise caused ~ 25-fold increase in plasma cfDNA just after bout that returned to baseline after 4 h. Within this time post-exercise urinary output of albumin (an indicator of exercise-induced damage to glomerular filtration membrane) and creatinine increased, while no significant changes in urinary cfDNA were noted. The urinary ratios of cfDNA to creatinine and to albumin decreased in post-exercise urine in comparison to resting arm of the exercise physiology study (4.8 ± 8.4 vs. 3.7 ± 5.7 ng/mg and 614.0 ± 586 vs. 324.7 ± 494.8 ng/mg, respectively, p < 0.05). These findings exclude cfDNA excretion with urine as the significant route of elimination of cfDNA released in response to exercise and suggest that it is not necessary to limit physical activity in urine donors for cfDNA analyses.