概述：

缺铁分为三个阶段：第一也即最常见的阶段，是铁质储量不足。。。

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PS:1秒左右有连字符，45秒左右有破折号

Athletes in high-impact sports such as running may also lose iron through a phenomenon where small blood vessels in the feet leak blood. There are three stages of iron deficiency. The first and most common is having low iron reserves, a condition that typically has no symptoms. Fatigue and poor performance may begin to appear in the second stage of deficiency, when not enough iron is present to form the molecules of blood protein that transport oxygen to the working muscles. In the third and final stage, people often feel weak, tired, and out of breath - and exercise performance is severely compromised.
运动员从事跑步之类高强度剧烈运动，也可能会因为足部血管失血的现象而使铁质流失。 缺铁分为三个阶段：第一也即最常见的阶段，是铁质储量不足。这一阶段一般没有症状。到了缺铁的第二阶段，就会出现疲倦和力不从心，此时体内已没有足够的铁来形成血蛋白分子，将氧输至运动肌肉。在第三即最后阶段，人常常感到虚弱、疲乏无力、喘不过气，运动成绩大打折扣。