No significant differences were found among water polo players having different SOD2, CAT, and GPx1 genotype with regard to preexercise plasma levels of dROMs, BAP, and total thiols (Table 2). Moreover, AOPP plasma concentrations were not significantly different in individuals with different CAT and GPx1 genotype, while they were found to be significantly higher in water polo players having the SOD2 AV16 genotype than in those with VV genotype (Table 2). Notably, after 90 minutes of exercise AOPP concentrations were significantly increased not only in individuals bearing the SOD2 AV16 but also in those with VV16 genotype in comparison with those bearing the AA genotype (Table 2). After exercise, plasma values of dROMs were increased, while those of BAP and free thiols were concomitantly decreased, in water polo players having either heterozygous or homozygous mutated genotype for SOD2 V16A, CAT −844 G>A, and GPx1 rs1800668 polymorphisms compared with those having wild-type genotypes (Table 2). However, these differences were found to be significant only for subjects having either the CAT GA genotype or GPx1 CT genotype (Table 2), likely due to the small group size.