Miller, Andrew D.

Acclimation to high altitude was characterized in nine non‐athletic college aged students aged 19 to 24 during a trek in the Himalayas. A three minute step test (40.6 cm step and a 24 step/minute rate) was performed at 1654 (am, day 1), 3696 (pm, day 1), 3865 (day 8), 3688 (day 10), 4115 (day 13) and again at 3688 meters (day 14). Resting heart rate and oxygen saturation (SaO 2 ) was measured prior to the step test and 20 seconds after exercise cessation (recovery). The heart rate difference (percent change) between pre‐ and post‐exercise cessation was used to measure hypoxic stress at altitude and significant acclimation could not be documented until day 14 (3688 m). The percent difference between pre‐ and post‐step test SaO 2 at 1654 m was significantly different from tests performed at 3696, 3865, 3688, and 4115 m. However, at day 14 (3688 m) the percent change in SaO 2 was no longer significantly different from the 1654 m value at day 1. Pre‐trip response to acute hypoxia (12.5 % O 2 ) was examined by performing the same step test at 402 m, with inconclusive results. This study suggests that 14 days are required for non‐athletic students to achieve acclimation to a step test.