Iron, copper, magnesium and zinc status as predictors of swimming performance.

The hypothesis that blood biochemical measurements of iron (Fe), copper (Cu), magnesium (Mg) and zinc (Zn) nutritional status and dietary intakes of these minerals are useful predictors of 100-yd free-style swimming performance during actual competition was examined in five female and five male collegiate swimmers. Dietary intakes of Fe, Cu, Mg, and Zn exceeded 70% of daily recommended or estimated safe and adequate intakes. Anemia was not present but body iron stores, assessed with serum ferritin concentration, were reduced in female swimmers who had significantly increased erythrocyte Mg and superoxide dismutase activity which suggest a biochemical adaptation to physical training. Actual 100-yd freestyle times (53.1 +/- 1.4 sec; mean +/- SE) measured during competition were similar to values (52.6 +/- 1.4 sec) predicted with models previously derived from other groups of swimmers. These findings indicate the important role of mineral nutritional status in facilitating the development of peak physical performance and support the hypothesis that mineral element nutritional status is one factor contributing to attainment of optimal human physiological function.