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Ventilatory Acclimatization to Intermittent Hypoxia in Well-Trained Runners and Swimmers

Townsend, Nathan E.1; Gore, Christopher J. FACSM2; Truijens, Martin J.3; Rodriguez, Fernando A.4; Stray-Gundersen, James FACSM5; Levine, Benjamin D. FACSM5

Medicine & Science in Sports & Exercise: May 2004 - Volume 36 - Issue 5 - p S337
Annual Meeting Abstracts: H-20 – Free Communication/Poster: Hypoxia
Free

1University of Sydney, Sydney, Australia.

2Australian Institute of Sport, Canberra, Australia

3Vrije Universiteit, Amsterdam, Netherlands.

4Universitat de Barcelona, Barcelona, Spain.

5Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas and UT Southwestern Medical Center, Dallas, TX.

Email: nathan.townsend@ausport.gov.au

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Intermittent hypoxia (IH) can induce ventilatory acclimatization in sedentary individuals, however, whether this adaptation occurs in athletes engaged in vigorous sea-level training has not been tested. PURPOSE: To examine measures of ventilatory acclimatization to IH in well-trained runners and swimmers. METHODS: 21 athletes (12 swimmers, 9 runners) were matched for gender, performance and training history, and randomly assigned to either hypobaric hypoxia (HYPO; simulated altitude of 4000–5500m) or normoxia (NORM; 0–500m) in a double-blind, placebo controlled design. Both groups rested 3 h.d−1, 5 d.wk−1 for 4 wk in a hypobaric chamber. Measures of resting ventilation (VE) and end-tidal PCO2 (PETCO2), isocapnic hypoxic ventilatory response (HVR; Δ VE/Δ SpO2), hypercapnic ventilatory response (HCVR; Δ VE/Δ PETCO2), and submaximal exercise VE were taken twice before IH or placebo (average = PRE), 3–4 d after (POST1), and 13–14 d after (POST2) the intervention. All measurements were conducted in normoxia. Results were analysed using a 2-way repeated measures ANOVA with two levels for group (HYPO, NORM) and three levels for day (PRE, POST1, POST2). RESULTS: The group × day interaction was nonsignificant for resting VE (p = 0.43), PETCO2 (p = 0.11), HVR (p = 0.84), HCVR (p = 0.92), and submaximal exercise VE (p = 0.93).

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CONCLUSIONS: Using the current protocol of IH, evidence of ventilatory acclimatization was not present in the HYPO group when compared to the NORM group. The brief daily periods of hypoxic exposure in this study may not have been a sufficient stimulus to induce ventilatory acclimatization in our subjects, who were engaged in high volume sea-level training.

©2004The American College of Sports Medicine