Iron supplementation improves lactate response and energetic (work) efficiency after training in non‐anemic female rowers

We conducted this trial to study the effects of deficiency without anemia (IDNA) on endurance performance in female collegiate rowers. At the beginning of a training season, 43 non‐anemic rowers were randomized to receive 100 mg/d FeSO 4 (N=22) or placebo (N=21) for 6 weeks using a double‐blind design. Iron status, body composition, and physical performance (4K Time trial‐TT) were assessed at baseline and after training. Thirty‐one rowers (N=15 iron, 16 placebo) completed the trial. After controlling for baseline iron status and supplement dose consumed, multiple regression analyses revealed improvements in log serum ferritin in the iron group compared to placebo (P=0.04), and the more depleted at baseline, the greater benefit from supplementation (P=0.05). After 6 weeks of training, while rowers in both groups increased their fat‐free mass and improved their endurance performance (VO2peak, energetic efficiency, lactate response), lactate response (as % of maximum lactate) during the early phase of the TT was significantly lower in the iron group compared to the placebo (P=0.05). Rowers in the iron group who consumed more of the supplement had a greater improvement in energetic efficiency compared to placebo. We conclude that iron supplementation improved female rowers' energetic efficiency and lactate response during a 4K TT after 6 weeks of training. Supported by the ADAF and Division of Nutritional Sciences.