Improved reliability of the urine lactate concentration under controlled hydration after maximal exercise.

CONTEXT: Urine lactate may be a novel biomarker of lactate production capacity but its reliability has been unsatisfactory so far. OBJECTIVE: To compare the reliability of urine lactate between controlled hydration and no hydration after maximal exercise. MATERIAL AND METHODS: Athletes performed swimming exercise four times: two followed by consumption of 1 L of water and two followed by no water intake. Blood and urine lactate was measured. RESULTS: The reliability of urine lactate was good and similar to that in blood only after controlled hydration. Blood and urine lactate were correlated under both hydration conditions. DISCUSSION AND CONCLUSION: Controlled hydration after exercise provides satisfactory reliability of urine lactate.

Redox, iron, and nutritional status of children during swimming training.

Effects of exercise training on important determinants of children's long-term health, such as redox and iron status, have not been adequately investigated. The aim of the present study was to examine changes in markers of the redox, iron and nutritional status of boy and girl swimmers during a prolonged period of training. 11 boys and 13 girls, aged 10-11 years, were members of a swimming club. They were assessed at the beginning of the training season, at 13 weeks and at 23 weeks through blood sampling and recording of the diet. Reduced glutathione increased at 13 and 23 weeks, whereas oxidised glutathione decreased at 13 weeks, resulting in an increase of the reduced/oxidised glutathione ratio at 13 and 23 weeks. Total antioxidant capacity, catalase, thiobarbituric acid-reactive substances, hemoglobin, transferrin saturation and ferritin did not change significantly. Carbohydrate intake was below 50% of energy and fat intake was above 40% of energy. Intakes of saturated fatty acids and cholesterol were excessive. Iron intake was adequate but intakes of folate, vitamin E, calcium and magnesium did not meet the recommended daily allowances. No significant differences were found between sexes in any of the parameters measured. In conclusion, child swimmers improved the redox status of glutathione during training, although the intake of antioxidant nutrients did not change. The iron status was not impaired by training. Suboptimal intake of several nutrients suggests the need for nutritional monitoring and education of children athletes.