title: Skeletal muscle morphology and aerobic capacity in patients with obstructive sleep apnoea syndrome.
abstract: BACKGROUND
  Despite the fact that patients with obstructive sleep apnoea syndrome (OSAS) often have symptoms at the level of skeletal muscle such as fatigue, the question of whether the structural, cellular and functional properties of limb skeletal muscles are affected has not been fully examined.
  
  
  OBJECTIVE
  The aim was to examine physiological and muscular parameters in patients with OSAS and to assess the relationship between these parameters and the clinical symptoms.
  
  
  METHODS
  Eighteen patients with OSAS and 16 controls participated. Aerobic capacity was assessed using a submaximal test. Fibre type distribution and fibre area were analyzed on muscle biopsies taken from the tibialis anterior. The microvascularization was assessed using the following parameters: (1) the number of capillaries per fibre (CAF), (2) CAF per fibre area (CAFA), (3) capillary to fibre perimeter exchange (CFPE) index, which represents the interface between muscle fibre and capillaries, and (4) length of capillary/perimeter of the fibre (LC/PF) index or capillary tortuosity, which represents the percent of muscle fibre perimeter in contact with the wall of the microvessel.
  
  
  RESULTS
  The OSAS group had significantly lower predicted relative maximal oxygen uptake (p = 0.0047) which was inversely correlated to the apnoea/hypopnoea index (AHI; r = -0.6, p = 0.017). There was a significantly higher CFPE index for slow type I fibres (p = 0.007) and fast type II fibres (p = 0.0126) and a significantly higher LC/PF index for type I fibres (p = 0.0003) and type II fibres (p = 0.0285) in OSAS patients compared to controls.
  
  
  CONCLUSIONS
  OSAS patients have a higher muscle microvascularization and a lower aerobic capacity than controls. Furthermore the aerobic capacity was inversely correlated to AHI.
authors.affiliation: Department of Clinical Medicine, Orebro University, Orebro, Sweden. bwl@du.se
authors.forename: Britta
authors.initials: B
authors.lastname: Wåhlin Larsson
authors.forename: Fawzi
authors.initials: F
authors.lastname: Kadi
authors.forename: Jan
authors.initials: J
authors.lastname: Ulfberg
authors.forename: Karin
authors.initials: K
authors.lastname: Piehl Aulin
mesh_terms: D000328:Adult; D000332:Aerobiosis; D001707:Biopsy, Needle; D002196:Capillaries / Q000473:pathology; D005260:Female; D006801:Humans; D007866:Leg; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000473:pathology; D018482:Muscle, Skeletal / Q000098:blood supply / Q000473:pathology*; D010101:Oxygen Consumption; D020181:Sleep Apnea, Obstructive / Q000473:pathology / Q000503:physiopathology*