Hemoglobin mass and performance responses during 4 weeks of normobaric “live high–train low and high”

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Purpose To investigate whether 4 weeks of normobaric “live high–train low and high” (LHTLH) causes different hematological, cardiorespiratory, and sea‐level performance changes compared to living and training in normoxia during a preparation season. Methods Nineteen (13 women, 6 men) cross‐country skiers competing at the national or international level completed a 28‐day period (∼18 h day −1 ) of LHTLH in normobaric hypoxia of ∼2400 m (LHTLH group) including two 1 h low‐intensity training sessions per week in normobaric hypoxia of 2500 m while continuing their normal training program in normoxia. Hemoglobin mass (Hb mass ) was assessed using a carbon monoxide rebreathing method. Time to exhaustion (TTE) and maximal oxygen uptake (VO 2max ) were measured using an incremental treadmill test. Measurements were completed at baseline and within 3 days after LHTLH. The control group skiers (CON) (seven women, eight men) performed the same tests while living and training in normoxia with ∼4 weeks between the tests. Results Hb mass in LHTLH increased 4.2 ± 1.7% from 772 ± 213 g (11.7 ± 1.4 g kg −1 ) to 805 ± 226 g (12.5 ± 1.6 g kg −1 ) ( p < 0.001) while it was unchanged in CON ( p = 0.21). TTE improved during the study regardless of the group (3.3 ± 3.4% in LHTLH; 4.3 ± 4.8% in CON, p < 0.001). VO 2max did not increase in LHTLH (61.2 ± 8.7 mL kg −1 min −1 vs. 62.1 ± 7.6 mL kg −1 min −1 , p = 0.36) while a significant increase was detected in CON (61.3 ± 8.0–64.0 ± 8.1 mL kg −1 min −1 , p < 0.001). Conclusions Four‐week normobaric LHTLH was beneficial for increasing Hb mass but did not support the short‐term development of maximal endurance performance and VO 2max when compared to the athletes who lived and trained in normoxia.