HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 292/5/R1977    most recent 00622.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Fu, Q. Articles by Levine, B. D. Search for Related Content PubMed PubMed Citation Articles by Fu, Q. Articles by Levine, B. D.

ENVIRONMENTAL, EXERCISE AND RESPIRATORY PHYSIOLOGY

Intermittent hypobaric hypoxia exposure does not cause sustained alterations in autonomic control of blood pressure in young athletes

¹Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, and The University of Texas Southwestern Medical Center at Dallas, Dallas; ³The University of North Texas Health Science Center, Fort Worth, Texas; ²Australian Institute of Sport, Canberra, Australia; ⁴Faculty of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands; and ⁵Institut Nacional d'Educació Física de Catalunya, Universitat de Barcelona, Barcelona, Spain

Submitted 31 August 2006 ; accepted in final form 29 December 2006

Intermittent hypoxia (IH), which refers to the discontinuous use of hypoxia to reproduce some key features of altitude acclimatization, is commonly used in athletes to improve their performance. However, variations of IH are also used as a model for sleep apnea, causing sustained sympathoexcitation and hypertension in animals and, thus, raising concerns over the safety of this model. We tested the hypothesis that chronic IH at rest alters autonomic control of arterial pressure in healthy trained individuals. Twenty-two young athletes (11 men and 11 women) were randomly assigned to hypobaric hypoxia (simulated altitude of 4,000–5,500 m) or normoxia (500 m) in a double-blind and placebo-controlled design. Both groups rested in a hypobaric chamber for 3 h/day, 5 days/wk for 4 wk. In the sitting position, resting hemodynamics, including heart rate (HR), blood pressure (BP), cardiac output (_c, C₂H₂ rebreathing), stroke volume (SV = _c/HR), and total peripheral resistance (TPR = mean BP/_c), were measured, dynamic cardiovascular regulation was assessed by spectral and transfer function analysis of cardiovascular variability, and cardiac-vagal baroreflex function was evaluated by a Valsalva maneuver, twice before and 3 days after the last chamber exposure. We found no significant differences in HR, BP, _c, SV, TPR, cardiovascular variability, or cardiac-vagal baroreflex function between the groups at any time. These results suggest that exposure to intermittent hypobaric hypoxia for 4 wk does not cause sustained alterations in autonomic control of BP in young athletes. In contrast to animal studies, we found no secondary evidence for sustained physiologically significant sympathoexcitation in this model.

altitude; autonomic nervous system; hemodynamics; arterial pressure; cardiovascular variability; baroreflexes

This article has been cited by other articles:

				P. N. Ainslie, M. Hamlin, J. Hellemans, P. Rasmussen, and S. Ogoh Cerebral hypoperfusion during hypoxic exercise following two different hypoxic exposures: independence from changes in dynamic autoregulation and reactivity Am J Physiol Regulatory Integrative Comp Physiol, November 1, 2008; 295(5): R1613 - R1622. [Abstract] [Full Text] [PDF]

				F. A. Rodriguez, M. J. Truijens, N. E. Townsend, J. Stray-Gundersen, C. J. Gore, and B. D. Levine Performance of runners and swimmers after four weeks of intermittent hypobaric hypoxic exposure plus sea level training J Appl Physiol, November 1, 2007; 103(5): 1523 - 1535. [Abstract] [Full Text] [PDF]