title: Effects of hypoxic interval training on cycling performance.
abstract: OBJECTIVE
  The aim of this study was to test the hypothesis that intermittent hypoxic interval training improves sea level cycling performance more than equivalent training in hypoxia or normoxia.
  
  
  METHODS
  Thirty-three well-trained cyclists and triathletes (25.9 +/- 2.7 yr, VO(2max) 66.1 +/- 6.1 mL.min(-1).kg(-1)) were divided into three groups: intermittent hypoxic (IHT, N = 11, P(I)O(2) of 100 mm Hg), intermittent hypoxic interval training (IHIT, N = 11) and normoxia (Nor, N = 11, P(I)O(2) of 160 mm Hg) and completed a 7-wk training program, consisting of two high-intensity (100 or 90% relative peak power output) interval training sessions each week. Each interval training session was performed in a laboratory on the subject's own bicycle, in normoxic or hypoxic conditions for the Nor and the IHT group, respectively. The IHIT group performed warm-up and cool-down plus recovery from each interval in hypoxic conditions. In contrast to IHT, interval exercise bouts were performed in normoxic conditions.
  
  
  RESULTS
  Mean power output during a 10-min cycle time trial improved after the first 4 wk of training by 5.2 +/- 3.9, 3.7 +/- 5.9, and 5.0 +/- 3.4% for IHIT, IHT, and Nor, respectively, without significant differences between groups. Moreover, mean power output did not show any significant improvement in the following 3 wk in any group. VO(2max) (L.min(-1)) increased only in IHIT during the training period (8.7 +/- 9.1%; P < 0.05). No changes in cycling efficiency or in hematological variables (P > 0.05) were observed.
  
  
  CONCLUSIONS
  Four weeks of interval training induced an improvement in endurance performance. However, short-term exposure to hypoxia (approximately 114 min.wk(-1)) did not elicit a greater increase in performance or any hematological modifications.
authors.affiliation: UPRES EA 3759 Faculty of Sport Sciences, 700 avenue Pic St Loup, 34090 Montpellier, France. belle.roels@univ-montpl.fr
authors.forename: Belle
authors.initials: B
authors.lastname: Roels
authors.forename: Grégoire P
authors.initials: GP
authors.lastname: Millet
authors.forename: Christophe J L
authors.initials: CJ
authors.lastname: Marcoux
authors.forename: Olivier
authors.initials: O
authors.lastname: Coste
authors.forename: David J
authors.initials: DJ
authors.lastname: Bentley
authors.forename: Robin B
authors.initials: RB
authors.lastname: Candau
mesh_terms: D000328:Adult; D004911:Erythrocyte Volume; D004912:Erythrocytes / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D013177:Sports
chemical_list: D006454:Hemoglobins