NORMOBARIC-HYPOXIA

Abstract

Currently, normobaric-hypoxic systems (altitude tents) are commercially available to provide athletes the option to “sleep high and train low”, which has been shown to result in significant improvements in hematological parameters and endurance performance. However, to date no scientific studies have been published elucidating the performance characteristics of these hypoxic modalities. Therefore, the purpose of this project was to evaluate selected physiological responses of elite athletes to intermittent, normobaric-hypoxia using a commercially available, one-person tent. Subjects consisted of elite endurance athletes (n = 6) who volunteered to spend 8 hours resting or sleeping for 5 consecutive nights at a simulated elevation of 2500m (FIO2 = 15.3%). During these periods the athletes were continuously monitored and the following parameters recorded: FIO2, FICO2, Hb-O2 saturation via pulse oximetry (SaO2), heart rate (HR), ambient temperature (Temp) and relative humidity (RH%). Due to tent design limitations, FIO2 required a significant amount of time to stabilize, therefore the data collected during the first two hours were not used for analysis. Following completion of each exposure, athletes subjectively rated comfort and health symptoms associated with acute mountain sickness using a standardized questionnaire; which revealed no negative side effects. Throughout all test exposures, the altitude tent setting remained fixed to produce an FIO2 = 15.3%. However, subject interaction decreased FIO2 an average of 5%; this was equivalent to an additional 323m in elevation. One safety concern was the production and increase of CO2 in the closed tent; this stabilized within approximately 30 min. This technology appears to provide a relatively comfortable alternative to hypobaric-hypoxia, which would allow athletes to effectively utilize the “sleep high, train low” model of altitude training. Average (± SD) values are as follows:Table