Plasma levels of redox markers, namely, dROMs, BAP, thiols, and AOPP, as well as enzyme activities of SOD, CAT, and GPX, were assessed in water polo players before and after exercise and are shown in Table 1. We observed that, in resting conditions, the mean levels of oxidated molecules (dROMs, AOPP) were increased, while antioxidant defenses (BAP, thiols) were reduced in comparison with normal reference ranges. This indicated a very high level of oxidative stress in water polo players recruited for this study. Postexercise mean plasma levels of dROMs, and those of BAP and total free thiols, were significantly higher and lower, respectively, than those before exercise. No significant changes after training were observed in mean plasma levels of AOPP as well as SOD, CAT, and GPx enzyme activities.