Iron supplementation and running performance in female cross-country runners

Abstract

The purpose of this study was to determine the effects of two weeks of high dosage iron supplementation on various blood iron indices and metabolic parameters in non-anemic, iron-depleted competitive female cross-country runners. The subjects were highly trained members of the Colorado State University cross-country team and were completing 40 to 50 miles of training weekly. A pretest, post-test single-blind crossover design was employed. Upon collection of baseline exercise blood and metabolic data, five subjects were randomly assigned to iron supplementation (650 mg ferrous sulfate; 130 mg elemental iron) and five subjects to placebo treatment. At two weeks the treatments were reversed. Exercise blood and metabolic data were collected at two-week intervals. Dietary iron intake was assessed using a three-day dietary survey. Dietary analysis revealed deficiencies in vitamin B-6, iron, magnesium, and zinc according to USRDA standards. Baseline blood samples revealed no deficiencies in iron storage or transport proteins. Two weeks of iron supplementation resulted in no significant increases in blood iron indices. Metabolic parameters related to running performance were also unchanged after iron supplementation. High dosage, short-term iron supplementation appears to have no effect on blood or metabolic parameters in iron-depleted but non-anemic female cross-country runners.