Data supports the relationship between ferritin and exercise performance in female athletes. Low ferritin in athletes is called sports anemia . Its more common in women. Increasing ferritin works for men too. Athletes do not need to be anemic for this to work,,,,just have suboptimal ferritin.
STUDY: Eur J Clin Nutr. 2007 Jan;61(1):30-9. Epub 2006 Jul 12. Iron supplementation maintains ventilatory threshold and improves energetic efficiency in iron-deficient nonanemic athletes. Hinton PS(1), Sinclair LM. Author information: (1)Department of Nutritional Sciences, University of Missouri, Columbia, MO 65211, USA. email@example.com
OBJECTIVE: To determine the effect of iron supplementation on iron status and endurance capacity. DESIGN: Randomized, double-blind iron supplementation.
SETTING: University of Missouri-Columbia and surrounding community.
SUBJECTS: Twenty iron-deficient (serum ferritin, sFer<16 microg/l; serum transferrin receptor, sTfR>8.0 mg/l; or sTfR/log sFer index >4.5), nonanemic (hemoglobin, Hb>120 g/l, women; >130 g/l, men) men and women (18-41 years) were recruited via fliers and newspaper advertisements; 20 of 31 eligible subjects participated.
INTERVENTIONS: A 30 mg measure of elemental iron as ferrous sulfate or placebo daily for 6 weeks.
RESULTS: Dietary iron intake and physical activity did not differ between groups before or after supplementation. Iron supplementation significantly increased sFer compared to placebo (P=0.01), but did not affect Hb or hematocrit. Iron supplementation prevented the decline in ventilatory threshold (VT) observed in the placebo group from pre- to post-supplementation (P=0.01); this effect was greater in individuals with lower sFer before intervention (P<0.05). Changes in sFer from pre- to post-treatment were positively correlated with changes in VT (P=0.03), independent of supplementation. The iron group significantly increased gross energetic efficiency during the submaximal test (P=0.04). Changes in sFer were negatively correlated with changes in average respiratory exchange ratio during the submaximal test (P<0.05).
CONCLUSIONS: Iron supplementation significantly improves iron status and endurance capacity in iron-deficient, nonanemic trained male and female subjects.