ALTERNATING DAYS AND CONTINUOUS EXPOSURES TO ALTITUDE LARGELY PRESENT SIMILAR ADAPTATIONS
Zupan, M. F., Lennemann, L., Herrera, M., & Walker, T. (2011). Impact of alternating days of intermittent hypoxic exposure (IHE) on physical performance at sea level, hypobaric hypoxic, and normobaric hypoxic environments. Medicine and Science in Sports and Exercise, 43(5). Supplement abstract 791.
Unacclimatized military personnel rapidly deployed to moderate altitude (2,750-4,400 m) environments are subject to physical performance impairments of up to 70%. Simulated altitude exposures in a normobaric hypoxic environment are currently being used to help pre-acclimatize some battlefield airmen before strenuous deployments to moderate altitude. The current recommended altitude preparation guidelines for using intermittent normobaric hypoxic exposure suggests five consecutive days at 4,000 m for 1.5 hours during the week prior to moderate altitude deployments. This is a difficult schedule to accomplish considering all the other pre-deployment tasks that are required. Alternating exposure days would lessen the time demands during a high-ops tempo on deploying airmen while still providing the necessary moderate altitude adaptations.
This study determined if alternating days of intermittent hypoxic exposure for unacclimatized, sea-level male residents (N = 7) works as well as or better than consecutive days to be part of a training strategy to minimize physical impairments in battlefield airmen during moderate altitude deployments. Baseline physical tests were conducted at sea-level, normobaric hypoxic, and hypobaric hypoxic environments. Ss were randomly assigned to either five consecutive or five alternating days of intermittent hypoxic exposure. All tests were repeated post-intermittent hypoxic exposures. Following a four-week washout interval, all Ss repeated the process again under the opposite intermittent hypoxic exposure schedule.
Significant physiological differences in oxygen saturation and VO2max between sea-level and normobaric hypoxic and hypobaric hypoxic conditions were observed. There were significant differences in the hypobaric hypoxic environment for anaerobic endurance distance, but not for VO2max or maximum heart rate between the alternating or consecutive days training regimens.
Implication. Alternating days of intermittent hypoxic exposure might result in the same or greater altitude adaptations than continuous days allowing battlefield airmen to better prepare themselves for moderate altitude deployments.
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