Taking iron supplements may help reduce some of the fatigue associated with strenuous exercise, suggests research published in a recent journal.
In a recent study, women taking iron supplements had a significant increase in muscle endurance compared to a placebo group, who showed no improvement after the same amount of daily exercise.
However, while the US researchers noted that tissue iron depletion may negatively affect endurance performance and muscle fatigability, they said that they were unable to confirm the relations between tissue iron improvement and decreased muscle fatigue.
Twenty iron-depleted, non-anaemic women received either an iron supplement (10mg) or placebo twice daily for six weeks in a randomised, double-blind trial. The researchers from Cornell University and the State University of New York assessed the rates of quadricep muscle fatigue seen during knee extension exercises.
While there were no significant differences between the groups in baseline iron status, after treatment, serum iron and transferrin (the protein that carries iron in the bloodstream) saturation increased significantly in the iron group. Serum transferrin receptor concentrations increased significantly in the placebo group but not in the iron group.
The group taking iron showed a decrease in fatigue, unlike the placebo group. In the iron group, MVC (fatigue measurement) at the sixth minute and MVC at the end of the trials were 15 per cent and 27 per cent higher respectively, after treatment.
These improvements were not related to changes in iron-status indexes or tissue iron stores, although power was low to detect these relations, wrote the researchers in the February issue of the American Journal of Clinical Nutrition.
However they concluded that iron supplementation was associated with a significant improvement in muscle fatigability.