title: O2 arterial desaturation in endurance athletes increases muscle deoxygenation.
abstract: OBJECTIVE
  The aim of this study was to compare the muscle deoxygenation measured by near infrared spectroscopy in endurance athletes who presented or not with exercise-induced hypoxemia (EIH) during a maximal incremental test in normoxic conditions.
  
  
  METHODS
  Nineteen male endurance sportsmen performed an incremental test on a cycle ergometer to determine maximal oxygen consumption (VO2max) and the corresponding power output (P(max)). Arterial O2 saturation (SaO2) was measured noninvasively with a pulse oxymeter at the earlobe to detect EIH, which was defined as a drop in SaO2 > 4% between rest and the end of the exercise. Muscle deoxygenation of the right vastus lateralis was monitored by near infrared spectroscopy and was expressed in percentage according to the ischemia-hyperemia scale.
  
  
  RESULTS
  Ten athletes exhibited arterial hypoxemia (EIH group) and the nine others were nonhypoxemic (NEIH group). Training volume, competition level, VO2max, Pmax, and lactate concentration were similar in the two groups. Nevertheless, muscle deoxygenation at the end of the exercise was significantly greater in the EIH group (P < 0.05).
  
  
  CONCLUSIONS
  Greater muscle deoxygenation at maximal exercise in hypoxemic athletes seems to be due, at least in part, to reduced oxygen delivery--that is, exercise-induced hypoxemia--to working muscle added to the metabolic demand. In addition, our finding is also consistent with the hypothesis of greater muscle oxygen extraction in order to counteract reduced O2 availability.
authors.affiliation: Laboratory of Multidisciplinary Analysis of Physical Activity, Faculty of Sport Sciences, University of Artois, Liévin, France.
authors.forename: Renaud
authors.initials: R
authors.lastname: Legrand
authors.forename: Saïd
authors.initials: S
authors.lastname: Ahmaidi
authors.forename: Wassim
authors.initials: W
authors.lastname: Moalla
authors.forename: Dominique
authors.initials: D
authors.lastname: Chocquet
authors.forename: Alexandre
authors.initials: A
authors.lastname: Marles
authors.forename: Fabrice
authors.initials: F
authors.lastname: Prieur
authors.forename: Patrick
authors.initials: P
authors.lastname: Mucci
mesh_terms: D016552:Ergometry; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D010092:Oximetry; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology; D019265:Spectroscopy, Near-Infrared
chemical_list: D010100:Oxygen