Under the influence of hypoxia, the adrenal glands release erythropoietin, which triggers a cascade of processes to form a hematological response. Exposure to altitudes above 1600-1800 meters is necessary to stimulate erythropoiesis. An increase in total hemoglobin mass by 1% per week at an altitude of 2,500 meters could result in an increase of total hemoglobin mass by 12% after a 12-week stay at that altitude. The individual secretion of erythropoietin directly influences the increase in total hemoglobin mass. There is also a clear relationship between the increase in total hemoglobin mass, and a change of 1 g/kg in total hemoglobin mass, according to scientific publications, results in a change of 4.4 ml/kg/min in maximal oxygen consumption.
Altitude also leads to non-hematological adaptations. Non-hematological adaptations include muscular, metabolic, and ventilatory adaptations. All of these adaptations lead to an increase in performance. Among muscular adaptations, we can distinguish improvement of mitochondrial function, an increase in capillarization and myoglobin in the muscles, and muscle buffering capacity. The metabolic effect refers to the stimulation of the glycolytic pathway and through ventilatory adaptations to hypoxia. Energetic properties are also improved, including energy efficiency, leading to an increase in performance.