title: Carbon monoxide exposure during exercise performance: muscle and cerebral oxygenation.
abstract: OBJECTIVE
  To investigate the effect of carbon monoxide (CO) in the inspired air as anticipated during peak hours of traffic in polluted megalopolises on cerebral, respiratory and leg muscle oxygenation during a constant-power test (CPT). In addition, since O(2) breathing is used to hasten elimination of CO from the blood, we examined the effect of breathing O(2) following exposure to CO on cerebral and muscle oxygenation during a subsequent exercise test under CO conditions.
  
  
  METHODS
  Nine men participated in three trials: (i) 3-h air exposure followed by a control CPT, (ii) 1-h air and 2-h CO (18.9 ppm) exposure succeeded by a CPT under CO conditions (CPT(COA)), and (iii) 2-h CO and 1-h 100% normobaric O(2) exposure followed by a CPT under CO conditions (CPT(COB)). All exercise tests were performed at 85% of peak power output to exhaustion. Oxygenated (Δ[O(2)Hb]), deoxygenated (Δ[HHb]) and total (Δ[tHb]) haemoglobin in cerebral, intercostal and vastus lateralis muscles were monitored with near-infrared spectroscopy throughout the CPTs.
  
  
  RESULTS
  Performance time did not vary between trials. However, the vastus lateralis and intercostal Δ[O(2)Hb] and Δ[tHb] were lower in CPT(COA) than in CPT. During the CPT(COB), the intercostal Δ[O(2) Hb] and Δ[tHb] were higher than in the CPT(COA). There were no differences in cerebral oxygenation between the trials.
  
  
  CONCLUSIONS
  Inspiration of 18.9 ppm CO decreases oxygenation in the vastus lateralis and serratus anterior muscles, but does not affect performance. Breathing normobaric O(2) moderates the CO-induced reductions in muscle oxygenation, mainly in the intercostals, but does not affect endurance.
authors.affiliation: Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia. mkeram@phed.uoa.gr
authors.forename: M E
authors.initials: ME
authors.lastname: Keramidas
authors.forename: S N
authors.initials: SN
authors.lastname: Kounalakis
authors.forename: O
authors.initials: O
authors.lastname: Eiken
authors.forename: I B
authors.initials: IB
authors.lastname: Mekjavic
mesh_terms: D000393:Air Pollutants / Q000009:adverse effects; D000397:Air Pollution / Q000009:adverse effects; D001921:Brain / Q000098:blood supply* / Q000378:metabolism; D002248:Carbon Monoxide / Q000009:adverse effects* / Q000097:blood; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000737:chemistry / Q000502:physiology*; D010100:Oxygen / Q000097:blood* / Q000378:metabolism; D012143:Respiratory Physiological Phenomena / Q000187:drug effects*; D055815:Young Adult
chemical_list: D000393:Air Pollutants; D002248:Carbon Monoxide; D010100:Oxygen