Effect of an iron supplement on body iron status and aerobic capacity of young training women

Serum iron deficiency has a high incidence in female athletes. We investigated the effects of a daily oral iron supplement, (160 mg) administered during an intensive 7-week physical training programme, on body iron status, and the maximal aerobic capacity (VO_2max) of 13 women (group A) compared to 15 who took a placebo (group B). The subjects were 19 years old. Blood samples were obtained before training began and on days 1, 7, 21 and 42 of training. They were analysed for packed cell volume (PVC) and for haemoglobin (Hb), 2,3-diphosphoglycerate (2,3-DPG), haptoglobin, iron and ferritin concentrations. The VO_2max was measured on days 0, 21 and 42 of training. Following 21 days of training Hb, PCV and ferritin were significantly higher (P≤0.01) in group A compared to group B. Over the training period Hb rose by 9.3% and 2.4% in groups A and B, respectively. At the end of training 66% of group B exhibited ferritin concentrations below 10 ng·ml^-1, while none of group A had such low values. Mean VO_2max of group A had increased by 7.5% following 21 days of training (P≤0.01) and by 15.3% after 42 days. No appreciable increase in VO_2max had occurred in group B by day 21 (significantly lower than VO_2max of group A;P≤0.05), however by day 42 it had increased by 14.3% (P≤0.05). In both groups 2,3-DPG·g Hb^-1 had increased significantly (P≤0.005) by day 7 (22%) and remained at that level for an additional 35 days. We concluded that a daily oral iron supplement given to young women during intensive training improved several haematological variables and their body iron status. This improvement was associated with an increased VO_2max only during the early stages of their training (day 21) compared with the placebo group.