The Effectiveness Of Iron Supplementation In Endurance Trained Females During The Week Of Menses

Abstract

Decreased work capacity due to iron deficiency anemia has been well documented. Athletes (particularly endurance trained) who train six or more hours per week are at a greater risk of developing an iron deficiency. Menstruating women carry an increased risk for iron deficiency regardless of training status due to monthly blood loss. PURPOSE: The purpose of this study was to examine the effect of one week of iron supplementation during the week of menses on serum ferritin (SF) and serum soluble transferrin receptor (sTfR) values, heart rate recovery (HRR), blood lactate (BLAC) values, predicted VO2max (VO2max), and exercise time to reach 85% of predicated max heart rate (EXTIME). METHODS: Fifteen pre-menopausal endurance trained females were randomly assigned to either an iron (FE) or placebo (PL) group. The FE group took a ferrous sulfate supplement (65mg of elemental iron) once a day for seven days during menses. Each group completed two testing sessions (baseline and menses) on a cycle ergometer to reach 85% of predicted max heart rate. Blood was taken at baseline and menses testing sessions and analyzed for BLAC, SF, and sTfR. The maximum workload achieved, time to end of trial, and HRR (within 10BPM of pre-exercise heart rate) was recorded for each participant during both trials. RESULTS: There were no significant differences in sTfR and SF values between FE and PL groups for baseline, menses, or supplementation. HRR was significantly (p = 0.033) faster in the FE group during menses testing sessions than the PL group (4.5 ± 2, 8.6 ± 6.5 mins respectively. There was no significant difference among participants' predicted VO2max at baseline or during menses testing sessions. EXTIME was not statistically different between the iron and placebo group for baseline, menses, or supplementation effect, respectively (P > 0.05). Pre and post exercise BLaclevels were not significantly different between iron and placebo groups for baseline, menses, or supplementation effect CONCLUSION: The significant supplementation effect on heart rate recovery in conjunction with trends observed in VO2, EXTIME, and BLAC levels are compelling. Findings illustrate one week of iron supplementation during the week of menses enhanced HRR in this sample of participants.