A water polo match is characterized by high intensity intermittent activity with periods of intensive muscular activity followed by periods of moderate exercise or even rest, which involves both aerobic and anaerobic metabolism . In elite female water polo players it has been observed that the concentration of blood biomarkers of oxidative stress and inflammation varies over the course of an agonistic season . Our results demonstrated that, at rest, athletes exhibited dROM, BAP, and AOPP plasma levels, representing valuable markers of oxidative stress, outside of the desirable concentration ranges, indicating an imbalance between prooxidants and antioxidants. Interestingly, AOPP plasma concentrations were higher than those previously observed in a group of elite hurdlers , in agreement with the suggested influence of training level and mode on oxidative stress. The high level of oxidative stress found in resting athletes, recruited for this study, was likely a consequence of the high-volume training required during the mesocycle preparatory phase. In addition, after training we observed a further increase in dROM values and a reduction in total antioxidant capacity in comparison to rest values. Training session of team sports and/or match may also lead to an inflammatory response associated with muscle injury due to eccentric contraction used in these sports . Notably, intensified training was shown to induce a biphasic response of total antioxidant capacity, represented by a significant increase after low- and high-volume training, and a decline after very high-volume training . This condition, together with weekly competition and a diet at low intake of fruits and vegetables, impeded the normal recovery of athletes and may play a major role in the development of chronic oxidative stress and cellular damage .