Training near sea level while living at an altitude of 1700 - 2000 m for a month enhances subsequent endurance performance, probably by increasing the oxygen-carrying capacity of the blood through an increase in production of red blood cells. Many athletes and coaches have generally accepted the idea that traditional altitude training-living and training high-benefits sea-level endurance performance. The question is what the best way to get an altitude exposure is. To answer this question, we controlled the effect of two types of getting the hypoxic influence - live high - train high (traditional concept) and live high - train low (new concept). The reasons for not having a positive effect are caused by the: insufficient acclimatization effect for elite athletes to stimulate an increase in red cell mass/haemoglobin mass because the altitude was too low(<1700 m) and/or the altitude training period was too short(<2-3 weeks); (2) the training effect at an altitude may have been compromised due to insufficient training stimuli for enhancing the function of the neuromuscular and cardiovascular systems; and (3) enhanced stress with possible overtraining symptoms and an increased frequency of infections. When comparing HiHi and HiLo (living high and training low), it is obvious that both can induce a positive effect and increase the oxygen transport capacity of blood, at least in 'responders' if certain prerequisites are met. The minimum dose to attain a haernatological effect is at least 3 weeks at an altitude. The increased oxygen transport capacity of blood allows training at higher intensity during and after HiLo, thereby increasing the potential to improve some haernatological and cardiovascular determinants of endurance performance. To interpret the changes correctly, by provoking an altitude exposure, different strategies need to be applied (HiHi and HiLo) as well as a concept of the magnitude and quality of the changes that matter to the considerable inter-individual variation in sea level performance after altitude training.
