Abstract
<jats:p>Background and purpose Aerobic capacity and hemoglobin mass (Hb_mass) are crucial physiological determinants of long-distance running performance. Traditional altitude training has long been used to enhance hematological adaptations, yet logistical and health challenges limit its accessibility. Simulated altitude training has emerged as a practical alternative, though evidence regarding its effectiveness remains inconsistent. This study aimed to investigate the effects of simulated altitude training on hemoglobin mass and aerobic endurance (VO₂max) in long-distance runners, providing controlled experimental evidence of its efficacy. Material and methods A quasi-experimental design with pre- and post-test control groups was employed. Forty trained runners (aged 18–25 years) were divided into two groups: 20 participants underwent six weeks of simulated altitude training using hypoxic conditions (FiO₂ 14–15%), while 20 participants trained under normoxic conditions. Hemoglobin mass was measured with a hematology analyzer, and VO₂max was assessed using a treadmill test with indirect calorimetry. Statistical analyses included paired t-tests and ANCOVA to evaluate within- and between-group differences. Results The experimental group demonstrated significant improvements in Hb_mass (+4.5%, p < 0.01) and VO₂max (+6.8%, p < 0.01), while the control group showed minimal, non-significant changes. ANCOVA confirmed that simulated altitude training had a significant effect on both variables after adjusting for baseline values. Conclusions Six weeks of simulated altitude training significantly enhanced hemoglobin mass and aerobic endurance in long-distance runners, validating its role as an effective and feasible alternative to natural altitude training. These findings support the integration of hypoxic simulation into endurance training programs, although further studies are required to assess long-term sustainability and individual variability in adaptation.</jats:p>