The effects of fitness-type exercise on iron status in adult women.

To determine if compromised iron status results from fitness-type exercise, 24 women from a 35-min, 4-day/wk aerobic exercise class provided blood samples at wk 0, 6, and 13. Hb increased from wk 0 to wk 6 (p less than 0.001), and decreased from wk 6 to wk 13 (p less than 0.001). Hematocrit did not change from wk 0 to wk 6, but decreased from wk 6 to wk 13 (p less than 0.005). Ferritin concentrations were lower at wk 6 and 13 (p less than 0.01 and p less than 0.05) than initially. No changes in these measures were detected among 11 sedentary control subjects. Intakes of iron, ascorbic acid, protein, and energy were comparable between exercise and sedentary groups. Decreased resting and recovery step test heart rates indicated improved aerobic fitness in exercising subjects from wk 2 to wk 11. Thirteen weeks of aerobic exercise class did not induce iron deficiency anemia. Decreased plasma ferritin concentrations suggest a compromise in iron stores which appears to be stabilized after 6 wk.