Relation between oxidative stress and antioxidant status during long-lasted endurance exercise at moderate intensity is not clear. The purpose of the study was to examine changes of oxidative stress and antioxidant status during 3 hours endurance exercise at intensity of 70% heart rate reserve (70%HRR) in well-trained cyclists. Eight college cyclists participated in this study after giving the informed consent. They performed a steady-state exercise that corresponded to HR of approximately 145 bpm for 3 hours on a cycle ergometer in a laboratory. Blood samples were taken at 5 time points: before exercise (Pre), at 1 hour (Ex 1h), 2 hours (Ex 2h), 3 hours (Ex 3h) during exercise and 1 hour after exercise ( Post 1h), to analyze the oxidative stress, the antioxidant status, plasma vitamin C (VC) and vitamin E (VE) concentrations. The oxidative stress and antioxidant status were determined by using the FRAS4 analyzer. The oxidative stress (d-ROM) did not change during and after exercise. However, the antioxidant status (BAP) and the plasma VC concentration were significantly higher in Ex 1h, Ex 2h, Ex 3h and Post 1h compared with Pre. On the other hand, no changes were found in the plasma VE concentration during and after exercise. In conclusion, endurance exercise for 3 hours at the intensity of 70%HRR increased the plasma antioxidant level, and this increase may contribute to inhibit exercise-induced oxidative stress in well-trained cyclists. We suggest that regular endurance training might improve the antioxidant status in trained athletes.

Iron deficiency in athletes induces negative effects on their athletic performances. The present study aimed to examine a possibility of non-invasive screening with urine ferritin value for iron deficiency by examining its association with serum ferritin value. A group of 30 male college soccer players,13 male endurance runners, 22 female volleyball players, and 9 female long distance runners voluntarily participated in this study. Blood samples were collected before breakfast. The urinary samples were collected to the special tube in the morning and analyzed by ELISA in accordance with the manufacture’s specification. The urinary ferritin value was significantly correlated with serum ferritin value (r=0.32, p<0.05). In addition, the corresponding association was improved in athletes whose urinary ferritin values were less than 2314 ng/gCre (n=52) (r=0.49, p<0.05). In each of male and female athletes, the results on the event-related differences in urinary ferritin had a similar trend as those on serum ferritin. In future studies, further testing should be accomplished using larger numbers of athletes for use the urine ferritin as non-invasive screening iron deficiency in athletes.