Abstract
PurposeTo determine the effect of intravenous iron supplementation on performance, fatigue and overall mood in runners without clinical iron deficiency.MethodsFourteen distance runners with serum ferritin 30–100 µg·L−1 were randomly assigned to receive three blinded injections of intravenous ferric-carboxymaltose (2 ml, 100 mg, IRON) or normal saline (PLACEBO) over four weeks (weeks 0, 2, 4). Athletes performed a 3,000 m time trial and 10×400 m monitored training session on consecutive days at week 0 and again following each injection. Hemoglobin mass (Hbmass) was assessed via carbon monoxide rebreathing at weeks 0 and 6. Fatigue and mood were determined bi-weekly until week 6 via Total Fatigue Score (TFS) and Total Mood Disturbance (TMD) using the Brief Fatigue Inventory and Brunel Mood Scale. Data were analyzed using magnitude-based inferences, based on the unequal variances t-statistic and Cohen's Effect sizes (ES).ResultsSerum ferritin increased in IRON only (Week 0: 62.8±21.9, Week 4: 128.1±46.6 µg·L−1; p = 0.002) and remained elevated two weeks after the final injection (127.0±66.3 µg·L−1, p = 0.01), without significant changes in Hbmass. Supplementation had a moderate effect on TMD of IRON (ES -0.77) with scores at week 6 lower than PLACEBO (ES -1.58, p = 0.02). Similarly, at week 6, TFS was significantly improved in IRON vs. PLACEBO (ES –1.54, p = 0.05). There were no significant improvements in 3,000 m time in either group (Week 0 vs. Week 4; Iron: 625.6±55.5 s vs. 625.4±52.7 s; PLACEBO: 624.8±47.2 s vs. 639.1±59.7 s); but IRON reduced their average time for the 10×400 m training session at week 2 (Week 0: 78.0±6.6 s, Week 2: 77.2±6.3; ES–0.20, p = 0.004).ConclusionDuring 6 weeks of training, intravenous iron supplementation improved perceived fatigue and mood of trained athletes with no clinical iron deficiency, without concurrent improvements in oxygen transport capacity or performance.
Highlights
Iron is an essential nutrient for the optimal functioning of the human body [1]
Iron deficiency is often classified as serum ferritin values below,22 mg?L21, with iron deficiency anemia diagnosed when iron stores are exhausted, and hemoglobin (Hb) levels fall below 12 g?L21 [6]
Study Population There were no significant differences between the IRON and PLACEBO groups at the start of the study in terms of baseline characteristics (Table 1), hematological parameters (Table 2), or mood scores associated with the Brunel Mood Scale (BRUMS) (Figure 2A)
Summary
Iron is an essential nutrient for the optimal functioning of the human body [1]. Integral for hemoglobin synthesis, iron plays an important role in many cellular processes; oxygen transport and storage, generation of energy through oxidative phosphorylation [1] and enzyme function affecting intracellular metabolism [2]. Iron assists immune function, DNA synthesis, the functioning of neurotransmitters and the formation of myelin, and is critical for normal brain function and cognitive development [3]. Exercise stress may exacerbate iron loss due to foot-strike hemolysis associated with running [5]. Iron deficiencies are common in athletic populations, and frequently manifest through feelings of lethargy, a lack of energy and lowered perceived ability to train and perform [4]. Iron deficiency is often classified as serum ferritin values below ,22 mg?L21, with iron deficiency anemia diagnosed when iron stores are exhausted (serum ferritin ,15 mg?L21), and hemoglobin (Hb) levels fall below 12 g?L21 [6]
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