DOES TRAINING ALTER BIOMARKERS OF IRON HOMEOSTASIS IN FEMALE COLLEGIATE ATHLETES RESIDING AT MODERATE ALTITUDE?

Abstract

Iron deficiency is reported to be more prevalent in female athletes compared to the general population, which can negatively affect athletic performance. Hepcidin (HEP) and erythroferrone (ERY) play a significant role in the homeostatic control of iron, but erythropoietic activity, inflammation, and red cell turnover also influence iron homeostasis. It is unknown whether these factors are altered in female athletes while training at altitude. PURPOSE: To determine how markers of iron homeostasis, including ferritin (fer), hemoglobin concentration (Hb), reticulocytes, HEP, ERY, interleukin 6 (IL6), and tumor necrosis factor alpha (TNFa), lactate dehydrogenase (LDH) and creatine phosphokinase (CPK) change during training in female endurance and team sport athletes residing at moderate altitude. METHODS: We recruited 94 female athletes from the University of Colorado DI cross country (XC; n = 28), nordic (n = 6) and alpine (n = 8) skiing, lacrosse (LAX; n = 35) and soccer teams (n = 17). In addition, 12 full time female college students were recruited as controls. Between 2 to 7 fasted blood samples were collected over a minimum of 3 months. All athletes were provided with oral iron supplements from a certified nutritionist during this period. RESULTS: Average fer and Hb were higher in endurance athletes (fer: 53 ± 30 ng/dL; Hg: 14.6 ± 0.8) compared to team sport athletes (31 ± 19; 13.8 ± 0.8) and controls (18 ± 9; 13.9 ± 1.1). Fer remained stable over time for all groups except LAX, who decreased by 20 ng/dL post season. HEP was higher in endurance (36.6 ± 60.3 ng/dL) compared to team sport athletes (18.0 ± 12.0), but there were no differences between groups for ERY (overall average: 10.1 ± 50.8 ng/dL); neither HEP or ERY changed significantly over time. In LAX, soccer, and nordic, IL6 and TNFa were lower than XC and remained stable over time; however, IL6 and TNFa started higher in XC and decreased over time. All teams except nordic showed fluctuations in LDH and CPK over the training cycle, but there were no differences between groups for these parameters or percent reticulocytes for any groups. CONCLUSION: Endurance athletes had higher Hb, fer, and HEP. While IL6 and TNFa were higher in XC athletes, other biomarkers of iron homeostasis tended to not be different between groups, although some parameters fluctuated over time.