Acute Effects Of Intermittent Hypoxia-hyperoxia Exposure On Immune Status In Healthy Physically Active Males - A Pilot Study

PURPOSE: Hypoxic environments affect various systems of the human body and are implemented as therapeutic treatments of the elderly or patients, as well as a performance enhancing strategy by athletes. The aim of the study was to investigate acute effects of an intermittent hypoxia-hyperoxia exposure (IHHE) on changes in immune cell counts over time in healthy, physically active students. METHODS: On four consecutive days, five young, male subjects aged 25.3 (24.9-27.2) years at a VO2max of 61.3 (53.0-63.1) ml/min/kg were exposed to a normobaric IHHE at rest using a hypoxicator (CellAir® Gecko Plus, Cellgym Technologies). Each Participant completed a hypoxic test to individualize the external hypoxic stimulus. The IHHE consisted of alternating cycles breathing air at 10-12% and 34% fraction of inspired oxygen (FIO2), thereby lowering peripheral oxygen saturation to 80%. Venous blood samples were collected on several occasions (pre, post 0, 0,5, 1, 2, 4 and 22 h) at the first (A) and fourth IHHE (B), and were then analyzed by flow cytometry (Cytoflex) and a hematology analyzer (Swelab Alfa) to detect leukocyte subpopulations (granulocytes, monocytes, lymphocytes including B-, T-, CD4 + -, CD8 + - and natural killer cells). RESULTS: Analysis revealed significantly lower values by Cytoflex compared to Swelab for all examined cell populations and over time (p < 0.05). The completion of the IHHE showed a significant difference of leukocyte (p = 0.046), granulocyte (p = 0.019) and CD4 + -lymphocyte counts (p = 0.040) only after the fourth IHHE (B), indicating an anticipated peak in cell count at least after 4 hours (leukocytes: +202%, granulocytes: +201%, CD4 + -lymphocytes: +309%). CONCLUSIONS: The hypoxic stimulus was well tolerated by all participants. Therefore, similarities to the acute reaction when exposing the elderly as well as patients to the same hypoxic stimulus should be evaluated. Interestingly, changes in cell counts only occurred on day B suggesting a certain habituation. Exercising at high intensity increases leukocyte and granulocyte counts and causes alterations in the immune system. Future studies may discuss effects of IHHE on immune function considering gender, age, fitness level or health status.