Iron May Improve Exercise Endurance

ALBANY, N.Y.--Iron supplementation may reduce muscle fatigue in non-anemic, iron-deficient women, according to a double blind, randomized study printed in the February issue of The American Journal of Clinical Nutrition (77, 2:441-8, 2003) (www.ajcn.org). Researchers from the State University of New York at Albany recruited 20 women who were randomly assigned to receive either iron or placebo for six weeks. Muscle fatigue was measured by the rate of decrease in maximal voluntary static concentrations (MVCs) during dynamic knee extensions.

After treatment, the iron group exhibited a reduction in the rate of decrease in MVCs, indicating a decrease in muscle fatigue was linked with supplementation. This effect was not seen in the placebo group. The women in the iron group also exhibited MVCs 15-percent higher at the sixth minute and 27-percent higher at the end of the fatigue protocol compared to the placebo group. However, researchers noted that these improvements were not related to changes in iron status indexes or iron tissue stores.

Researchers concluded iron supplementation was associated with a decrease in muscle fatigue, although they noted their study was not set up to detect relationships between tissue iron improvement and decreased muscle fatigue.