["The reactive oxygen species produced as a result of exercise might exceed an individual's antioxidant defence system. Various endogenous antioxidants are elevated in adult athletes, resulting in an improved antioxidant capacity. However, little is known about antioxidant defence in adolescents. The purpose of this study was to examine presumed adaptations of antioxidant capacity in exercising adolescents.", 'Trolox-equivalent antioxidant capacity (TEAC), uric acid and nutritional antioxidants were measured in the plasma of 91 male and 98 female athletes (mean age 15.9 +/- 2.0 years) and compared to those of 18 male and 22 female sedentary controls (mean age 16.3 +/- 2.1 years). Antioxidant intake was calculated using 4-day dietary records.', 'Neither male nor female athletes showed differences in alpha-tocopherol, beta-carotene or ascorbate intake compared to controls. Plasma levels of alpha-tocopherol and carotenoids in athletes and controls did not differ either. Nevertheless, athletes of both sexes had higher TEAC values than their respective controls (male athletes 1.48 +/- 0.22 mmol/l vs. male controls 1.23 +/- 0.19 mmol/l, female athletes 1.47 +/- 0.20 mmol/l vs. female controls 1.15 +/- 0.04 mmol/l, p < 0.05).'] Does exercise increase the plasma antioxidant capacity of adolescent athletes?