title: Muscle oxygenation, EMG, and cardiovascular responses for cabin attendants vs. controls.
abstract: BACKGROUND
  The goal was to investigate the effect of acute moderate hypobaric exposure on the physiological responses to sustained contractions (local) and light to moderate dynamic exercise (systemic) for cabin attendants (CAB) and a matched control group (CON).
  
  
  METHODS
  There were 14 CAB and 13 CON who participated. The experimental protocol was designed as a 2 x 2 randomized crossover study for which subjects performed a forearm isometric test and a cycling test in normobaric (NORM) and hypobaric [HYPO; 574 mmHg approximately 8000 ft (2440 m) above sea level (ASL)] conditions. Oxygen saturation (StO2%) was measured in the extensor carpi radialis muscle at rest and during an isometric wrist extension (20% MVC). Heart rate (HR), ventilation (V(E)), and oxygen uptake (VO2) were measured at rest, during cycling exercise at intensities of 50 W and 100 W, and during recovery. Blood samples were collected and analyzed for hemoglobin concentrations.
  
  
  RESULTS
  Local response: There was a significant effect of HYPO for both CAB and CON with a decrease in StO2% of 6.5% both at rest and during contraction. Systemic response: there was no general effect of HYPO on HR, VE, or VO2. No differences were found between groups in either the local or systemic response or in the blood parameters.
  
  
  CONCLUSIONS
  This study shows an effect of moderate hypobaric exposure on local muscle oxygenation during rest and sustained contraction. Whether this has an impact on fatigue development during work among cabin attendants is discussed.
authors.affiliation: Institute of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Noerre alle 51, DK-2200 Copenhagen, Denmark. sandfeld@ifi.ku.dk
authors.forename: Jesper
authors.initials: J
authors.lastname: Sandfeld
authors.forename: Lisbeth Højkjaer
authors.initials: LH
authors.lastname: Larsen
authors.forename: Albert Guy
authors.initials: AG
authors.lastname: Crenshaw
authors.forename: Bente Rona
authors.initials: BR
authors.lastname: Jensen
mesh_terms: D000328:Adult; D000337:Aerospace Medicine; D000399:Air Pressure; D018592:Cross-Over Studies; D004576:Electromyography; D005080:Exercise Test; D005260:Female; D005542:Forearm; D006339:Heart Rate; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology*; D010100:Oxygen / Q000600:supply & distribution*; D010101:Oxygen Consumption / Q000502:physiology*; D010313:Partial Pressure; D019265:Spectroscopy, Near-Infrared
chemical_list: D010100:Oxygen