For a woman who already has a poor iron status, any additional iron loss from exercise may be enough to tip her over the edge into a more serious deficiency, ...(Para. 5) If a woman who already has less iron than necessary starts a program of exercise that causes more loss of iron then her iron status will change greatly and she'll be put in a more serious state of iron deficiency, tip(sb )over the edge: bring about a noticeable change;(cause to) develop into another status• For a woman who already has a poor iron status, any additional iron loss from exercise may be enough to tip her over the edge into a more serious deficiency, … (Para. 5) If a woman who already has less iron than necessary starts a program of exercise that causes more loss of iron, then her iron status will change greatly and she'll be put in a more serious state of iron deficiency, … tip (sb.) over the edge: bring about a noticeable change; (cause to) develop into another status