Abstract of Doctoral Thesis
Title ： Effect of exercise and nutritional intervention on hepcidin levels in endurance athletes
Doctoral Program in Sport and Health Science Graduate School of Sport and Health Science Ritsumeikan University
イシバシ アヤ ISHIBASHI Aya
Hepcidin is a key mediator of iron homeostasis in body, and it may explain exercise-induced iron deficiency. The purpose of the present study was to investigate effect of exercise and nutritional intervention on hepcidin levels in endurance athletes.
【Study 1】
We compared iron status, in particular serum hepcidin levels, between female long distance runners (n = 20) and untrained females (n = 15). As a result, serum hepcidin levels at rest tended to be higher in female long distance runners than those in untrained female. Moreover, serum iron levels and transferrin saturation were significantly lower in female long distance runners.
【Study 2】
We compared serum hepcpdin levels between intensified training period and normal training period in female long distance runners (n =16). As a result, serum hepcidin levels at rest were significantly elevated during intensified training period.
【Study 3】
We investigated time course changes in serum hepcidin levels after twice a day endurance training(endurance training in morning and afternoon) in female long distance runners (n =13).
Consequently, twice a day endurance training increased significantly serum hepcidin levels until the following morning. Moreover, an inverse correlation was observed between serum hepcidin levels and leptin levels.
【Study 4】
We investigated effect of three consecutive days of endurance training (twice 75 min treadmill run/day) on serum hepcidin levels in male endurance athletes (n = 14). The influence of iron supplementation (24 mg/day) during training period was also determined. As a result, serum hepcidin levels were significantly elevated following three consecutive days of endurance training when moderate doses of iron were taken during training period.
【Study 5】
We investigated effect of three consecutive days of endurance training on serum hepcidin levels under different energy availability in male long distance runners (n = 7). As a result, three consecutive days of endurance training under low energy availability (below 20 kcal/kg LBM) lowered significantly muscle glycogen content. Moreover, serum hepcidin levels were elevated during three consecutive days of endurance training under low energy availability.
These results indicate that increased training volume augments serum hepcidin levels at rest in endurance athletes. Moreover, prolonged exercise (run) increases acutely serum hepcidin levels during post-exercise period. Furthermore, both moderate dose of iron supplementation and low energy availability during endurance training period increase serum hepcidin levels at rest.
Therefore, the present findings suggest that endurance training attenuates iron metabolism mediated by elevated hepcidin levels in endurance athletes. Furthermore, nutritional status (e.g., amount of iron intake, energy availability) during endurance training period affects hepcidin response.
