Impact of Energy Availability, Health, and Sex on Hemoglobin-Mass Responses Following Live-High–Train-High Altitude Training in Elite Female and Male Distance Athletes

Purpose : The authors investigated the effects of sex, energy availability (EA), and health status on the change in hemoglobin mass (ΔHbmass) in elite endurance athletes over ∼3–4 wk of live-high–train-high altitude training in Flagstaff, AZ (2135 m; n = 27 women; n = 21 men; 27% 2016 Olympians). Methods : Precamp and postcamp Hbmass (optimized carbon monoxide rebreathing method) and iron status were measured, EA was estimated via food and training logs, and a Low Energy Availability in Females Questionnaire (LEAFQ) and a general injury/illness questionnaire were completed. Hypoxic exposure (h) was calculated with low (600 h) groupings. Results : Absolute and relative percentage ΔHbmass was significantly greater in women (6.2% [4.0%], P