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The effect of intermittent hypobaric hypoxic exposure and sea level training on submaximal economy in well-trained swimmers and runners

¹Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas and University of Texas Southwestern Medical Center at Dallas, Dallas, Texas; ²Institut Nacional d'Educació Física de Catalunya, Universitat de Barcelona, Spain; ³New South Wales Institute of Sport, Sydney, Australia; ⁴Faculty of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands; ⁵Australian Institute of Sport, Canberra; and ⁶Exercise Physiology Laboratory, School of Education, Flinders University, Adelaide, Australia

Submitted 21 November 2006 ; accepted in final form 19 November 2007

To evaluate the effect of intermittent hypobaric hypoxia combined with sea level training on exercise economy, 23 well-trained athletes (13 swimmers, 10 runners) were assigned to either hypobaric hypoxia (simulated altitude of 4,000–5,500 m) or normobaric normoxia (0–500 m) in a randomized, double-blind design. Both groups rested in a hypobaric chamber 3 h/day, 5 days/wk for 4 wk. Submaximal economy was measured twice before (Pre) and after (Post) the treatment period using sport-specific protocols. Economy was estimated both from the relationship between oxygen uptake (O₂) and speed, and from the absolute O₂ at each speed using sport-specific protocols. O₂ was measured during the last 60 s of each (3–4 min) stage using Douglas bags. Ventilation (E), heart rate (HR), and capillary lactate concentration ([La^–]) were measured during each stage. Velocity at maximal O₂ (velocity at O₂max) was used as a functional indicator of changes in economy. The average O₂ for a given speed of the Pre values was used for Post test comparison using a two-way, repeated-measures ANOVA. Typical error of measurement of O₂ was 4.7% (95% confidence limits 3.6–7.1), 3.6% (2.8–5.4), and 4.2% (3.2–6.9) for speeds 1, 2, and 3, respectively. There was no change in economy within or between groups (ANOVA interaction P = 0.28, P = 0.23, and P = 0.93 for speeds 1, 2, and 3). No differences in submaximal HR, [La^–], E, or velocity at O_2max were found between groups. It is concluded that 4 wk of intermittent hypobaric hypoxia did not improve submaximal economy in this group of well-trained athletes.

altitude; running; swimming