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Iron Supplementation Improves Energetic Efficiency in Iron-Depleted Female Rowers


Medicine & Science in Sports & Exercise: June 2014 - Volume 46 - Issue 6 - p 1204–1215
doi: 10.1249/MSS.0000000000000208
Applied Sciences

Purpose Studies in both animals and humans show a relationship between iron depletion without anemia (IDNA) and physical performance. Compared with their sedentary counterparts, female endurance athletes are at greater risk of IDNA, and consequences relevant to endurance athletes include reduced work capacity and energetic efficiency (EF). We conducted a randomized placebo-controlled trial to investigate the effects of iron (Fe) supplementation on Fe status and performance in nonanemic female rowers during training.

Methods At the beginning of a training season, 40 rowers were randomized to receive either 100 mg·d−1 FeSO4 (n = 21) or placebo (n = 19) using a double-blind design. Thirty-one (n = 15 Fe, 16 placebo) completed the 6-wk trial. Fe status (hemoglobin, serum ferritin, soluble transferrin receptor), body composition, and laboratory tests of physical performance (4-km time trial, V˙O2peak, energetic EF, and blood lactate) were assessed at baseline and after training.

Results Rowers in both groups increased their fat-free mass (P < 0.001) and V˙O2peak (P < 0.001) after training. Multiple regression analyses revealed improvements in Fe stores (serum ferritin) in the Fe treatment group after controlling for baseline Fe stores (P = 0.07). Rowers in the Fe group had slower lactate response during the first half of the time trial and after 5 min of recovery (P = 0.05) and showed greater improvements in energy expenditure (P = 0.01 for group-by time) and energetic EF compared with placebo (P = 0.03 for group-by time).

Conclusions Female rowers with depleted Fe stores who consumed supplemental Fe during training improved their Fe status and energetic EF during endurance exercise. These results are important for endurance athletes whose dietary patterns and physical training increase their risk of IDNA and suggest that Fe supplementation may maximize the benefits of endurance training.

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1Department of Medicine, Division of Gastroenterology and Hepatology, Medical University of South Carolina, Charleston, SC; and 2Division of Nutritional Sciences, Cornell University, Ithaca, NY

Address for correspondence: Diane M. DellaValle, Ph.D., R.D., Division of Gastroenterology and Hepatology, Department of Medicine, Nutrition Center, Medical University of South Carolina, Charleston, SC; E-mail:

Submitted for publication May 2013.

Accepted for publication October 2013.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (

© 2014 American College of Sports Medicine