Abstract

The purpose of this case study was to quantify the changes in basic haematological indices and swimming performance after intermittent normobaric hypoxia exposure (IHE) in two Olympian swimmers. Two female swimmers, middle-distance (MD) age 18 years, and long-distance (LD) age 22 years, completed a 15-day continuous regimen of 60-min a day IHE. Following routine pool training in the morning, swimmers were exposed to hypoxia for 6 min by having them breathe through a simulated device that restricted delivery of O₂ to the body. This was followed by 4 min of normoxia breathing room air. Hypoxic conditions were replicated in a graded declination in percentage of O₂ saturation as recommended by manufacturer: 90% (for the first 2 days), 85% (second 2 days), 80% (third 2 days) and 75% (last 9 days). Before and after the IHE, blood samples were collected for the analysis of red cell count (RBC), haemoglobin concentration (Hb) and haematocrit (Hct) while a 16×100-m incremental swimming test (with the final 100 m in all-out effort) was conducted to track performance changes. There were no significant changes in RBC, Hb or Hct of either swimmer after IHE. Heart rate during the graded swim test was the same before and after IHE. Rating of perceived exertion during each stage was lowered in MD but unaltered in LD. Performance time of 100 m all-out effort showed 4.8% and 1.6% declines in MD and LD, respectively. IHE does not seem to bring about positive changes in haematological response and swimming performance of highly competitive female swimmers. This might be because the hypoxic dose of IHE in the present study did not reach the threshold stimulus for haematological and performance benefits.