EFFECTS OF INTERMITTENT HYPOBARIC HYPOXIA AND ALTITUDE TRAINING ON PHYSIOLOGICAL AND PERFORMANCE PARAMETERS IN SWIMMERS

Abstract

The use of intermittent hypobaric hypoxia (IHH) is based on the assumption that brief exposures to relatively high levels of hypoxia, when maintained for an appropriate period, would stimulate erythropoiesis, and ultimately enhance VO2max and/or endurance performance. PURPOSE To examine the effect of two models of altitude training on swimming performance and physiological parameters in well trained swimmers: sea-level (SL) training combined with exposure to IHH in a hypobaric chamber, and training at real altitude. METHODS In the first experiment, 16 swimmers of high national level (8 males, 8 females), combined training at SL with exposure to IHH over 2 weeks (3 h/d) at a simulated altitude of 4,000 to 5,500 m. After giving their informed consent, subjects were matched and randomly assigned to the experimental group or to a control group. Before and after the program, all subjects took part in two testing sessions:a) a two-speed test (2x400m), followed by a maximal 100-m swim; and b) a 200m time-trial. In the second experiment, 5 of these subjects lived and trained during 3 weeks at a real altitude of 1,850 m. RESULTS The swimmers exposed to IHH improved swimming performance in the 200m trial (−1.3 s; p = 0.001). This improvement was associated with an increase in VO2peak in the 200-m test (+9.3%; p = 0.026), and VO2max (+5.4%; p < 0.001). These changes were paralleled by a significant increase in erythrocyte and reticulocyte counts, hemoglobin concentration, and hematocrit (p < 0.05) that were not observed in controls. CONCLUSION These results prove that training at SL combined with very short, intermittent exposure to moderate-severe hypobaric hypoxia (equivalent to 4,000–5,500 m) is able to improve SL, middle-distance swimming performance due to an increase in maximal aerobic power. We were unable to demonstrate that conventional altitude training at 1,850 m evokes significant comparable improvements, although similar trends were observed in some physiological parameters.