Moderate exercise-induced changes in the iron status of young adult women

Sujatha Rajaram, Purdue University

Abstract

The effect of moderate aerobic exercise on the iron status of previously sedentary college-age women was determined by conducting a short-term (12 Wks) and a long-term (24 Wks) study. In the first study, subjects (N = 60) were randomly assigned to one of the following groups: (1) 50 mg/d iron supplement, low iron diet; (2) 10 mg/d iron supplement, low iron diet; (3) Placebo, free choice diet; (4) Meat supplement to achieve recommended allowance for iron; and (5) Control, free choice diet. The long-term study (N = 62) was designed similarly and had all the above groups except the group that received the 10 mg/d iron supplement. In both the studies, all groups except the control were required to exercise a minimum of 3d/wk at 70-90% of their maximal heart rate. VO$\sb{2max}$ was measured at baseline and at the end of the study. Blood was sampled at baseline and every 4 weeks thereafter. Iron status indices were measured in both the studies. Mechanisms inducing changes in the iron status were also elucidated in the long-term study. In the short-term study, a decline in hemoglobin at the end of 4 weeks was observed in all the exercising groups. Transferrin saturation and serum ferritin were also negatively impaired in exercising subjects in study 1. The results from the long-term study in terms of changes in iron status were not as striking as the short-term study probably because of a higher baseline iron status in these subjects. However, a repeated time measures analysis of covariance with baseline hemoglobin as covariate indicated a significantly (p $\le$ 0.05) lower post hemoglobin in the Placebo group of study 2, compared to the iron supplemented groups. A significant drop in serum ferritin was detected in the Placebo group after 24 weeks of exercise. The results from both these studies together indicate that moderate aerobic exercise can compromise iron status in previously untrained women. An initial declining trend in haptoglobins in the exercising groups and a significant increase in serum erythropoietin in the Placebo group after 24 weeks suggest that a mild hemolysis might be occurring with exercise. However, a significant increase in haptoglobins at week 24 in the Meat group and an overall improvement in the iron status indices in the meat and iron supplemented groups in both the studies indicate that the initial alterations in the iron status induced by moderate aerobic exercise can be offset by oral iron therapy or by meeting the daily iron requirements through muscle food consumption.

Degree

Ph.D.

Advisors

Weaver, Purdue University.

Subject Area

Nutrition|Sports medicine

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