Effects of iron repletion on blood volume and performance capacity in young athletes

Purpose: The purpose of this study was to find out whether iron repletion l eads to an increase in red blood cell volume (RBV) and performance capacity in iron-deficient nonanemic athletes. Methods: 40 young elite athletes (13 -25 yr) with low serum ferritin (<20 <mu>g.L-1) and normal hemoglobin (male s > 13.5 g.dL(-1), females > 11.7 g.dL(-1)) were randomly assigned to 12-wk treatment with either twice a day ferrous iron (equivalent to 2 x 100 mg e lemental iron) or with placebo using a double blind method. Before and afte r treatment, hematological measures and parameters of iron status were dete rmined in venous blood. REV, blood volume (BV), and plasma Volume (PV) were measured by CO rebreathing For determination of the aerobic and anaerobic capacity (maximal accumulated oxygen deficit, MAOD), the athletes performed an incremental as well as a highly intensive treadmill test. Results: Afte r 12 wk, ferritin levels were within the normal range in the iron-treated g roup (IG) with a significant (P < 0.001) mean increase by 20 <mu>g.L-1 oppo sed to a slight nonsignificant decrease in the placebo group (PG). RBV did not change significantly in either group nor did any of the hematological m easures. However, only in IG there were significant increases in (V) over d ot O-2max and in O-2 consumption in the MAOD test. MAOD and maximal capilla ry lactate concentration remained unchanged in both treatment groups. Concl usions: The results indicate that in young elite athletes with low serum fe rritin and normal hemoglobin concentration iron supplementation leads to an increase in maximal aerobic performance capacity without an augmentation o f RBV.