Iron repletion decreases maximal exercise lactate concentrations in female athletes with minimal iron-deficiency anemia.

We studied the effect of 2 weeks of iron therapy on exercise performance and exercise-induced lactate production in trained women athletes: six control subjects with normal parameters of iron status and nine with mild iron-deficiency anemia defined by low Fe/TIBC, ferritin, and minimally decreased Hgb values. Iron therapy improved the abnormal measures of iron status and low Hgb in the second group to normal. Exercise performance in a progressive work-exercise protocol on a bicycle ergometer to exhaustion was unchanged after iron therapy in both groups; however, blood lactate levels at maximum exercise in the iron-deficient group decreased significantly from 10.3 +/- 0.6 mmol/L before therapy to 8.42 +/- 0.7 after therapy (p less than 0.03). The control subjects did not significantly alter lactate levels after maximal exercise on iron compared to placebo: 8.3 +/- 0.8 mmol/L vs. 8.5 +/- 0.7. Although there was not a significant difference in maximum exercise performance after iron therapy, these data support animal experiments implying that iron may play a role in oxidative metabolism and that minimal decreases in Hgb may impair arterial oxygen content enough to affect aerobic metabolism. In addition, these findings may have important implications for competitive women athletes in whom mild iron deficiency may go unnoticed.