Effects Of Exercise On The Iron Homeostasis And The Mechanisms

In published literature, the data about the effect of exercise on the human hematological iron status in the athletes has suggested the increased, decreased or unchanged response of the hematological iron status to exercise, in both the female and the male athletes. In this study, the articles that studied the effect of exercise training on the iron status of the female and male athletes, written in English, were collected to analyze the changes of the hematological iron status after the long-term endurance exercise as compared to the before, by a comprehensive analysis method(Meta—analysis) . In addition, the effect of long-term swimming exercise on the hematological iron status in the animal model under the condition of high iron content in diet was observed, and then their IRP(iron-regulatory protein) binding activity to the iron responsive element (IRE) in the liver was investigated to explore the mechanisms of the iron homeostasis.Methods(1) To analyze comprehensively the change of iron status in athletes under long-term endurance exercise. Previous literature that reported relevant parameters of both exercise and iron status of athletes, in English being published before 2005, was searched by computer through PubMed Medicine database, and then by artificial searching in the relevant journals. According to the profiles about the study subjects, training periods, training programs, training intensity, laboratory assay methods and the values of the iron status, the articles were screened on the basis of the established included and excluded criterions, and thus the iron status databases in the different gender groups were established respectively. Based on the Homogeneity test, the usage of the fixed or randomized effect model was determined.(2) To observe the effect of long-term swimming exercise on the hematological iron status in the animal model under the condition of high iron content in diet and on their IRP binding activity in the liver. The twenty healthy female Sprague-Dawley (SD) rats, aged three months and weighed 180～200g, were used, and divided randomly into the two groups: a sedentary group( SG, n=10) and an exercise group (EG, n=10). The rats in the EG swam for 2h/d and 5d/w. At the end of the three months, the hematological indices, including RBC counts, hemoglobin (Hb) concentration, hematocrit(Hct), plasma iron concentration (PI) , transferrin saturation (TS) and total iron binding capacity (TIBC), were assayed, and then both the IRP binding activity to the iron responsive elements (IRE) and their total binding activity in the liver were analyzed by the developed electrophoretic mobility shift assays (EMSA) .Results(1) The changes of exercise training on the hematological iron status of athletes after exercise training. As compared to the before, the female athletes had the statistically declined serum ferritin (Fn) concentration without the changes of the serum iron(SI), TS, Hb concentration and Hct. As compared to the before, the male athletes had the statistically declined serum Fn concentration and Hct; without the changes of SI, TS and Hb concentration.(2) The effect of long-term swimming exercise on the hematological iron status in the animal model under the condition of high iron content in diet and on the IRP binding activity in the liver. As compared to the SG, the rats in the EG had the declined TS and the raised TIBC without the changes of their RBC counts, Hb, Hct and PI concentration; both their IRP binding activity and their IRP total binding activity in the liver increased significantly without the changes of their ratio.ConclusionsGenerally, the published literature has suggested that the female athletes have the higher sensitivity of the hematological iron status to exercise because of the effect on their menses. In this study, however, the results suggest that both the female and the male athletes may have the declined iron storage without anemia after long-term training, and that the male athletes have the declined Hct as well. The results from the animal model after long-term exercise suggested that the long-term exercise can result in the declined TS and raised TIBC without changes of the PI concentration and anemia under the condition of the higher iron content in diet, and that the exercise can lead to an increase of the IRP contents in the liver and thus increase of the IRP-IRE binding capacity for regulating of the iron homeostasis at the post-transcription level.