title: Effect of acute hypoxia on maximal exercise in trained and sedentary women.
abstract: OBJECTIVE
  The purpose of this study was to determine the physiological responses of sedentary and endurance-trained female subjects during maximal exercise at different levels of acute hypoxia.
  
  
  METHODS
  Fourteen women who were sea level residents were divided into two groups according to their level of fitness: 1) endurance-trained women (TW) (N = 7), VO(2max) = 56.3 +/- 4.7 mL.kg(-1).min(-1); and 2) sedentary women (SW) (N = 7), VO(2max) = 34.8 +/- 5.6 mL.kg(-1).min(-1). Subjects performed four maximal cycle ergometer tests in normoxia and under hypoxic conditions (F(I)O(2) = 0.187, 0.154, and 0.117, corresponding to altitudes of 1000, 2500, and 4500 m, respectively).
  
  
  RESULTS
  VO(2max) decreased significantly by 3.6 +/- 2.1, 14 +/- 2.5, and 27.4 +/- 3.6% in TW, and by 5 +/- 4, 9.4 +/- 6.4, and 18.7 +/- 7% in SW at 1000, 2500, and 4500 m, respectively. The drop of VO(2max) (DeltaVO(2max)) was greater in TW at and above 2500 m. Arterial O2 saturation (SpO(2)) at maximal exercise was lower in TW at every altitude (1000 m: 90.9 +/- 1.9 vs 94.6 +/- 1.4%; 2500 m: 82.8 +/- 2.8 vs 90.0 +/- 2.1%; 4500 m: 65.0 +/- 4.7 vs 73.6 +/- 4.5%). Maximal heart rate decreased significantly from 1000 m in the two groups. SpO(2) was correlated to DeltaVO(2max) at 4500 m (r = -0.81, P < 0.01) and 2500 m (r = -0.81, P < 0.01), but not below. Furthermore, we noted a relationship between SpO(2) and O2 pulse (VO(2)/HR) at every F(I)O(2).
  
  
  CONCLUSIONS
  These results demonstrate that endurance-trained women show a greater decrement in VO(2max) at high altitudes. This could be explained mainly by a higher arterial desaturation, which is largely caused, according to our results, by diffusion limitation.
authors.affiliation: Laboratory of Functional and Cellular Responses to Hypoxia, UFR-SMBH Universite Paris, 74 rue Marcel Cachin, 93017 Bobigny Cedex, France. xwoorons@laposte.net
authors.forename: Xavier
authors.initials: X
authors.lastname: Woorons
authors.forename: Pascal
authors.initials: P
authors.lastname: Mollard
authors.forename: Christine
authors.initials: C
authors.lastname: Lamberto
authors.forename: Muriel
authors.initials: M
authors.lastname: Letournel
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Richalet
mesh_terms: D000328:Adult; D000531:Altitude; D001784:Blood Gas Analysis; D016552:Ergometry; D015444:Exercise / Q000502:physiology*; D005260:Female; D006339:Heart Rate; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption
chemical_list: D010100:Oxygen