Performance of runners and swimmers after four weeks of intermittent hypobaric hypoxic exposure plus sea level training

1 Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas and University of Texas Southwestern Medical Center at Dallas, Dallas, Texas; 2 Institut Nacional d'Educació Física de Catalunya, Universitat de Barcelona, Barcelona, Spain; 3 New South Wales Institute of Sport, Sydney, Australia; 4 Australian Institute of Sport, Canberra, Australia; 5 Faculty of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands; and 6 Exercise Physiology Laboratory, School of Education, Flinders University, Adelaide, Australia Submitted 21 November 2006 ; accepted in final form 6 August 2007 This double-blind, randomized, placebo-controlled trial examined the effects of 4 wk of resting exposure to intermittent hypobaric hypoxia (IHE, 3 h/day, 5 days/wk at 4,000–5,500 m) or normoxia combined with training at sea level on performance and maximal oxygen transport in athletes. Twenty-three trained swimmers and runners completed duplicate baseline time trials (100/400-m swims, or 3-km run) and measures for maximal oxygen uptake ( O 2max ), ventilation ( E max ), and heart rate (HR max ) and the oxygen uptake at the ventilatory threshold ( O 2 at VT) during incremental treadmill or swimming flume tests. Subjects were matched for sex, sport, performance, and training status and divided randomly between hypobaric hypoxia (Hypo, n = 11) and normobaric normoxia (Norm, n = 12) groups. All tests were repeated within the first (Post1) and third weeks (Post2) after the intervention. Time-trial performance did not improve in either group. We could not detect a significant difference between groups for a change in O 2max , E max , HR max , or O 2 at VT after the intervention (group x test interaction P = 0.31, 0.24, 0.26, and 0.12, respectively). When runners and swimmers were considered separately, Hypo swimmers appeared to increase O 2max (+6.2%, interaction P = 0.07) at Post2 following a precompetition taper and increased O 2 at VT (+8.9 and +12.1%, interaction P = 0.007 and 0.006, at Post1 and Post2). We conclude that this "dose" of IHE was not sufficient to improve performance or oxygen transport in this heterogeneous group of athletes. Whether there are potential benefits of this regimen for specific sports or training/tapering strategies may require further study. altitude; hypobaria; running; swimming Address for reprint requests and other correspondence: B. D. Levine, Institute for Exercise and Environmental Medicine, Presbyterian