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Ascorbic acid or vitamin C is involved in a number of biochemical pathways that are important to exercise metabolism and the health of exercising individuals. This review reports the results of studies investigating the requirement for vitamin C with exercise on the basis of dietary vitamin C intakes, the response to supplementation and alterations in plasma, serum, and leukocyte ascorbic acid concentration following both acute exercise and regular training. The possible physiological significance of changes in ascorbic acid with exercise is also addressed. Exercise generally causes a transient increase in circulating ascorbic acid in the hours following exercise, but a decline below pre-exercise levels occurs in the days after prolonged exercise. These changes could be associated with increased exercise-induced oxidative stress. On the basis of alterations in the concentration of ascorbic acid within the blood, it remains unclear if regular exercise increases the metabolism of vitamin C. However, the similar dietary intakes and responses to supplementation between athletes and nonathletes suggest that regular exercise does not increase the requirement for vitamin C in athletes. Two novel hypotheses are put forward to explain recent findings of attenuated levels of cortisol postexercise following supplementation with high doses of vitamin C.

This paper presents an overview of vitamin ${\text{B}}_6$ and exercise, including the role that vitamin ${\text{B}}_6$ plays in gluconeogenesis and glycogenolysis and changes in vitamin ${\text{B}}_6$ metabolism during exercise. The dietary vitamin ${\text{B}}_6$ intakes of athletes are also reviewed. Most studies report that male athletes have adequate dietary intakes of vitamin ${\text{B}}_6$ , whereas some females, especially those with low energy intakes, appear to have low vitamin ${\text{B}}_6$ intakes. Few studies have assessed the vitamin ${\text{B}}_6$ status of nonsupplementing athletes using the recommended status criteria. The role that vitamin ${\text{B}}_6$ may play in attenuating the rise in plasma growth hormone observed during exercise is also reviewed. Finally, recomrnendations are given for further research in the area of vitamin ${\text{B}}_6$ and exercise.