title: Inspiratory fraction as a marker of skeletal muscle dysfunction in patients with COPD.
abstract: BACKGROUND
  An inspiratory capacity to total lung capacity (IC/TLC) ratio of ≤25% has emerged as a better marker of mortality in chronic obstructive pulmonary disease (COPD) patients. The relationship among the IC/TLC ratio to lower extremity skeletal muscle function remains unknown.
  
  
  METHODS
  Thirty-five men with moderate to severe COPD were divided into those with IC/TLC≤25% (n=16) and >25% (n=19). The subjects were tested for thigh muscle mass volume (MMT), maximal strength, power output of the lower extremities, and physical activity.
  
  
  RESULTS
  Total MMT in the IC/TLC<25% group was significantly lower (413.91±89.42cm3) (p<0.001) than in the IC/TLC>25% group (575.20±11.76cm3). In the IC/TLC≤25% group, maximal strength of the lower extremities and muscle peak power output of the lower extremities were 36-56% lower (p<0.01) than among the patients in the IC/TLC>25% group.
  
  
  CONCLUSIONS
  IC/TLC≤25% is associated with reduced maximal strength and peak power output of the lower extremities. IC/TLC≤25% may have an important clinical relevance as an index to determine peripheral muscle dysfunction.
authors.affiliation: Department of Pulmonary Medicine B, Complejo Hospitalario de Navarra, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Cebollero
authors.affiliation: Department of Health Sciences, Public University of Navarre, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Zambom-Ferraresi
authors.affiliation: Department of Pulmonary Medicine B, Complejo Hospitalario de Navarra, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Hernández
authors.affiliation: Department of Pulmonary Medicine B, Complejo Hospitalario de Navarra, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Hueto
authors.affiliation: Department of Pulmonary Medicine B, Complejo Hospitalario de Navarra, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Cascante
authors.affiliation: Department of Health Sciences, Public University of Navarre, Spain. Electronic address: milagros.anton@unavarra.es.
authors.forename: M M
authors.initials: MM
authors.lastname: Anton
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D007320:Inspiratory Capacity; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology*; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D014109:Total Lung Capacity
keywords: Chronic obstructive pulmonary disease; Inspiratory fraction; Limb muscle dysfunction; Muscle mass; Muscle power; Muscle strength