The Impact Of Three Consecutive Days Of Endurance Training In Hypoxia On Hepcidin Responses.

Abstract

Endurance exercise in hypoxia resulted in similar hepcidin elevation compared with exercise in normoxia (Govus et al. 2014; Goto et al. 2017). However, how consecutive days of endurance training in hypoxia affects hepcidin elevation remains unclear. PURPOSE: The purpose of the present study was to determine the effect of three consecutive days of endurance training in hypoxia on hepcidin response. METHODS: Nine active healthy males completed two trials on different days, consisting of either three consecutive days of endurance training in hypoxia (FiO2: 14.5%) or normoxia (FiO2: 20.9%). They performed 90-min sessions of endurance training consisting of high-intensity endurance interval exercise (10 × 4 min pedaling at 80% of VO2max with 2 min of active rest at 30% of VO2max) followed by 30 min continuous pedaling at 60% of VO2max during three consecutive days (days 1-3). Venous blood samples were collected after an overnight fast during experimental periods (days 1-4) to determine the serum hepcidin, iron, ferritin and haptoglobin concentrations. RESULTS: Pedaling workload during endurance training were significantly lower in the HYP (interval exercise: 166 ± 4.3 W) than in the NOR (194 ± 7.6 W, P < 0.0001). Serum iron (P < 0.0001) and ferritin (P = 0.005) concentrations on days 2-4 significantly increased in both trials, whereas there was no significant difference between the two trials. Serum haptoglobin concentrations did not significantly change throughout the experimental periods in either trial. Moreover, NOR showed significantly greater serum hepcidin elevation on the days 2-4 compared with day 1 (day1: 13.9 ± 8.6 ng/mL, day2: 30.4 ± 9.9 ng/mL, P = 0.004). However, no significant difference was observed in serum hepcidin concentrations between the NOR and HYP. CONCLUSION: Three consecutive days of endurance training in hypoxia did not affect further hepcidin elevation compared with endurance training in normoxia.