Effects of Pre-acclimatization Applying the ‘‘Climb High and Sleep Low’’ Maxim: An Example of Rapid but Safe Ascent to Extreme Altitude

Pre-acclimatization at a convenient high-altitude location may represent an appropriate method before climbing a more hostile target mountain. The aim of the present field report was to demonstrate the effectiveness of such pre-acclimatizing applying the ‘‘climb high sleep low’’ maxim for a subsequent rapid ascent to almost 7000 m. After some pre-acclimatization in the Alps the authors flew to Chile for further pre-acclimatization in the Aymara village of Putre (3650 m). From there they undertook sojourns up to altitudes of 5700 m within 3 days. Subsequently they went back to Arica (sea level) and climbed Ojos del Salado (6893 m) within 5 days without any health problems. Measurements of heart rate and arterial oxygen saturation and of cerebral oxygenation by near infrared spectroscopy at rest and during exercise indicated adequate acclimatization status. This field report demonstrates highly effective pre-acclimatization by the ‘‘climb high and sleep low’’ strategy supporting anecdotal reports. The up and down strategy may likely have induced hypoxia (pre)conditioning and subsequently allowed rapid ascent to extreme altitudes without any complications. The duration of the carry-over effect after pre-acclimatization has to be evaluated and proposed physiological mechanisms have to be proved by controlled studies in