title: Living high-training low increases hypoxic ventilatory response of well-trained endurance athletes.
abstract: This study determined whether "living high-training low" (LHTL)-simulated altitude exposure increased the hypoxic ventilatory response (HVR) in well-trained endurance athletes. Thirty-three cyclists/triathletes were divided into three groups: 20 consecutive nights of hypoxic exposure (LHTLc, n = 12), 20 nights of intermittent hypoxic exposure (four 5-night blocks of hypoxia, each interspersed with 2 nights of normoxia, LHTLi, n = 10), or control (Con, n = 11). LHTLc and LHTLi slept 8-10 h/day overnight in normobaric hypoxia (approximately 2,650 m); Con slept under ambient conditions (600 m). Resting, isocapnic HVR (DeltaVE/DeltaSp(O(2)), where VE is minute ventilation and Sp(O(2)) is blood O(2) saturation) was measured in normoxia before hypoxia (Pre), after 1, 3, 10, and 15 nights of exposure (N1, N3, N10, and N15, respectively), and 2 nights after the exposure night 20 (Post). Before each HVR test, end-tidal PCO(2) (PET(CO(2))) and VE were measured during room air breathing at rest. HVR (l. min(-1). %(-1)) was higher (P < 0.05) in LHTLc than in Con at N1 (0.56 +/- 0.32 vs. 0.28 +/- 0.16), N3 (0.69 +/- 0.30 vs. 0.36 +/- 0.24), N10 (0.79 +/- 0.36 vs. 0.34 +/- 0.14), N15 (1.00 +/- 0.38 vs. 0.36 +/- 0.23), and Post (0.79 +/- 0.37 vs. 0.36 +/- 0.26). HVR at N15 was higher (P < 0.05) in LHTLi (0.67 +/- 0.33) than in Con and in LHTLc than in LHTLi. PET(CO(2)) was depressed in LHTLc and LHTLi compared with Con at all points after hypoxia (P < 0.05). No significant differences were observed for VE at any point. We conclude that LHTL increases HVR in endurance athletes in a time-dependent manner and decreases PET(CO(2)) in normoxia, without change in VE. Thus endurance athletes sleeping in mild hypoxia may experience changes to the respiratory control system.
authors.affiliation: School of Exercise and Sport Science, Faculty of Health Sciences, University of Sydney, Lidcombe, New South Wales 2141, Australia.
authors.forename: Nathan E
authors.initials: NE
authors.lastname: Townsend
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Gore
authors.forename: Allan G
authors.initials: AG
authors.lastname: Hahn
authors.forename: Michael J
authors.initials: MJ
authors.lastname: McKenna
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Aughey
authors.forename: Sally A
authors.initials: SA
authors.lastname: Clark
authors.forename: Tahnee
authors.initials: T
authors.lastname: Kinsman
authors.forename: John A
authors.initials: JA
authors.lastname: Hawley
authors.forename: Chin-Moi
authors.initials: CM
authors.lastname: Chow
mesh_terms: D000064:Acclimatization; D000531:Altitude; D001642:Bicycling; D002245:Carbon Dioxide; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D010313:Partial Pressure; D010806:Physical Education and Training; D010807:Physical Endurance; D012119:Respiration; D012146:Rest; D013990:Tidal Volume
chemical_list: D002245:Carbon Dioxide