Increased oxidative stress indices in the blood of child swimmers.

The blood redox status of child athletes is compared with that of age-matched untrained individuals. In the present study, 17 swimmers (10.1 +/- 1.6 years) and 12 non-athletes (9.9 +/- 1.1 years) participated. Reduced glutathione (GSH) was lower by 37% in swimmers compared to non-athletes (P < 0.01), oxidized glutathione (GSSG) was not different and their ratio (GSH/GSSG) was lower by 43% in swimmers compared to non-athletes (P < 0.01). Thiobarbituric acid-reactive substances concentration was higher by 25% in swimmers compared to controls. Catalase exhibited a strong trend toward lower levels in swimmers (P = 0.08). Finally, total antioxidant capacity was found lower by 28% in swimmers compared to controls (P < 0.05). In conclusion, we report that children participating in swimming training exhibit increased oxidative stress and less antioxidant capacity compared to untrained counterparts and suggest that children may be more susceptible to oxidative stress induced by chronic exercise.

Exercise-induced oxidative stress in G6PD-deficient individuals.

PURPOSE: This study was designed to investigate whether individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency can exercise without greater perturbations in their redox status compared with non-G6PD-deficient individuals. METHODS: Nine males with established G6PD deficiency and nine males with normal G6PD activity performed two exhaustive treadmill exercise protocols of different duration (the shorter one lasting 12 min and the longer one 50 min). Several hematological parameters, reduced glutathione (GSH), oxidized glutathione (GSSG), thiobarbituric acid reactive substances (TBARS), protein carbonyls, catalase, and total antioxidant capacity (TAC) were measured in the blood before and after each exercise bout. RESULTS: Both GSH and GSSG were significantly higher in the control group compared with the G6PD-deficient group at baseline (0.404 +/- 0.101 vs 0.195 +/- 0.049 mmol.L(-1) for GSH and 0.047 +/- 0.012 vs 0.012 +/- 0.006 mmol.L(-1) for GSSG; P < 0.05); as a result, their ratio was not significantly different between the two groups (P > 0.05). All other oxidative stress indices were not different between groups at rest (P > 0.05). Exercise of both durations affected significantly (P < 0.05) and similarly the levels of all oxidative stress indices either in the G6PD-deficient group or in the control group. Only the long exercise affected GSH status significantly (P < 0.05), whereas both short and long exercise increased the levels of TBARS, protein carbonyls, catalase activity, and TAC to a similar extent (P < 0.05). CONCLUSION: G6PD-deficient individuals are able to exercise until exhaustion without higher oxidative stress compared with non-G6PD-deficient individuals. Exercise duration is an important determinant of the magnitude of exercise-induced changes for GSH, GSSG, and GSH/GSSG, but not for TBARS, protein carbonyls, catalase activity, or TAC.