Resting serum antioxidant status is positively correlated with peak oxygenuptake in endurance trained runners

Background This study tested the hypothesis that the ability to scavenge fr ee radicals in serum was compromised in trained runners. Methods. Experimental design: peak (V) over dot O-2, the ability to scaveng e free radicals in serum and the plasma concentration of malondialdehyde (M DA) were assessed in 18 male runners. Participants: subject characteristics (mean+/-SEM) were height 1.77+/-0.01 m, mass 71.4+/-1.2 kg, age 31+/-1 yea rs and weekly training distance 45+/-5 km.week(-1). Measures: venous blood samples were collected at rest. Serum total antioxidant capacity (TAC) was determined using a chemiluminescent technique. This involved the oxidation of luminol, in a reaction catalysed by horseradish peroxidase, Serum antiox idant protection was quantified relative to a soluble vitamin E analogue (T rolox) and expressed as Trolox equivalents (Trolox Eq.). MDA was determined using a highly specific assay, using HPLC with fluorimetric detection. Pea k (V) over dot O-2 was determined from expired gas measurements collected d uring an incremental running test on a motorised treadmill. Data were analy sed using Pearson correlations. Results. Serum TAC was 500+/-26 mu mol Trolox Eq.l(-1), with a plasma MDA c oncentration of 1.5+/-0.1 mmol.l(-1) and serum urate concentration of 274+/ -12 mmol.l(-1). Peak (V) over dot O-2 was 63+/-1 ml.kg(-1).min(-1). Signifi cant correlations were observed between peak (V) over dot O-2 and serum TAC (r=0.365, p<0.05); peak (V) over dot O-2 and serum urate (r=0.463, p<0.05) and serum urate and serum TAC (r=0.807, p<0.001). Plasma MDA and serum TAC were not significantly correlated (r=0.026, p>0.05). Conclusions, These data demonstrate that the ability to quench free radical s in serum is increased in relation to the maximum ability to consume oxyge n, however this response does not appear to provide any additional protecti on against peroxidative damage at rest.