Purpose: The purpose of this study was to determine the effects of 3 consecutive days of endurance training in hypoxia on hepcidin responses.
Method: Nine active healthy males completed two trials, consisting of 3 consecutive days of endurance training in either hypoxia [fraction of inspired oxygen (FiO2): 14.5%) or normoxia (FiO2: 20.9%). On days 1-3, participants performed one 90 min session of endurance training per day, consisting of high-intensity endurance interval exercise [10 × 4 min of pedaling at 80% of maximal oxygen uptake ([Formula: see text]O2max) with 2 min of active rest at 30% of [Formula: see text]O2max] followed by 30 min of continuous exercise at 60% of [Formula: see text]O2max. Venous blood samples were collected prior to exercise each day during the experimental period (days 1-4) to determine serum hepcidin, iron, ferritin, haptoglobin, and ketone body concentrations.
Result: Serum iron (p < 0.0001), ferritin (p = 0.005) and ketone body (p < 0.0001) concentrations increased significantly in both trials on days 2-4 compared with day 1, with no significant differences between trials. No significant changes in serum haptoglobin concentrations were observed throughout the experimental period in either trial. Serum hepcidin concentrations also increased significantly on days 2-4 compared with day 1 in both trials (p = 0.004), with no significant differences observed between trials.
Conclusion: 3 consecutive days of endurance training in hypoxia did not affect hepcidin concentrations compared with endurance training in normoxia.
Keywords: Endurance training; Hepcidin; Hypoxia; Iron metabolism.