Altitude reduces the partial pressure of oxygen in inspired air, which lowers arterial oxygen saturation and limits maximal aerobic power. VO2max falls at altitude, meaning the oxygen delivery ceiling for sustained high-intensity effort is reduced. Early experimental evidence and practical guidance from Benjamin D. Levine University of Texas Southwestern Medical Center and James Stray-Gundersen University of Montana established the physiological basis for altitude exposure and proposed the live high–train low approach to preserve training intensity while gaining acclimatization benefits. Individual responses vary widely, so interventions must be personalized.
Physiological mechanisms
Reduced oxygen availability increases ventilation and heart rate at a given workload and stimulates renal production of erythropoietin, raising hemoglobin mass over days to weeks. This hematological adaptation can improve sea-level oxygen transport if maintained, but it requires adequate iron stores and appropriate timing. Christopher J. Gore Australian Institute of Sport has reviewed how changes in plasma volume, muscle oxygen extraction, and metabolic adjustments also determine performance outcomes. There are trade-offs: hypoxia impairs the ability to perform high-intensity intervals, so raw training stimulus can decline without careful planning.
Training strategies and consequences
For marathoners, the main rationale for altitude work is to increase aerobic capacity indirectly through greater red-cell mass and to provoke metabolic adaptations useful for long-duration effort. The live high–train low model aims to combine acclimatization with preserved intensity. However, prolonged or poorly managed altitude camps can produce overreaching, iron depletion, and increased illness risk, reducing training quality. Acute mountain conditions can also provoke acute mountain sickness, which has clear short-term consequences for sleep, appetite, and recovery.
Cultural and territorial context matters: highland regions such as the Ethiopian Highlands and the Kenyan Rift Valley are common birthplaces and training bases for elite distance runners, where lifelong exposure to altitude interacts with genetic, lifestyle, and socio-economic factors to shape endurance potential. Tim Noakes University of Cape Town has emphasized that environmental exposure is only one element among many that produce elite performers. Practically, marathon preparation should weigh competition altitude, planned acclimatization period, iron monitoring, and carefully structured intensity to balance the physiological benefits and the training costs of hypoxia.