Intermittent Hypobaric Hypoxia: an alternative training method at sea level to improve acclimatization and performance at altitude

摘要

Thirty one young athletes, 21 men and 10 women, 14-18 years old (judo:18, swimming:8, table tennis:5) were exposed to Intermittent Hypobaric Hypoxia (IHH). The study was done in the hypobaric chamber of the Asociacion Chilena de Seguridad in Antofagasta, one month before the Juegos Trasandinos de la Juventud 2001. Athletes were selected after precompetition medical examinations. At the beginning and end of the study, changes in hemoglobin (Hb) levels were measured, after a 12-min field test at sea level and a physical fitness test at a simulated altitude of 4,500m in the hypobaric chamber. The 4-week protocol included progressive IHH from 3,000m to 4,500m, with 3 hours daily, 3 times a week, and a 500m increase per week. In each session athletes used a cycloergometer for 15-30 min according to their tolerance, with a 70% heart rate reserve as the upper limit. Other techniques, depending on the sport, were also carried out. A smal! but significant increase in Hb was observed in both sexes (women 7.9% and men 4.7%). All subjects showed an improvement in Hb % saturation, double cardiac product (DCP) and rating of perceived exertion (RPE), according to the Borg scale, at two sub-maximal charges (50 and 100 watts) at a simulated altitude of 4,500m. In addition, distance run in 12 min. increased for both sexes (from 2,150 m to 2,315 m, p=0.04 for women and from 2,692 m to 2,777 m, p=0.08 for men). According to the Lake Louise Survey for Acute Mountain Sickness symptoms at the Oruro competition were 20.7%, 27.5%, 24.2% and 3.5% for days 1 to 4, respectively. Days 2-4 were the competition days. All athletes competed, except one woman who developed acute bronchitis. Conclusions: When it is not possible train at altitude in natural conditions before competing in a sports event, IHH can be an alternative to improve acclimation, stimulate erytrhopoiesis and increase sub-maximal aerobic power.