title: The relationship between fat-free mass index and pulmonary hyperinflation in COPD patients.
abstract: OBJECTIVE
  Reduced fat-free mass (FFM), a common finding in chronic obstructive pulmonary disease (COPD), may indirectly impact peak exercise capacity through a greater level of pulmonary hyperinflation. We aimed to investigate if FFM index (FFM/squared height) impacts exercise induced dynamic hyperinflation in COPD patients.
  
  
  METHODS
  Fifty-four patients with moderate-to-very severe COPD performed a symptom limited incremental cardiopulmonary exercise tests with serial measurements of inspiratory capacity (IC). FFM was measured by whole-body bioelectrical impedance.
  
  
  RESULTS
  Patients were 66.7 ± 7.7 years old with mean forced expiratory volume in 1 s (FEV₁) of 1.08 ± 0.41 L (42 ± 15% of predicted). Peak exercise IC was significantly (P < 0.05) correlated with IC at rest (r = 0.78), FEV₁(r = 0.66), FVC (r = 0.59), FFM (r = 0.38) and FFM index (r = 0.29). However, only FEV₁ and rest IC predict peak IC (r = 0.86; P < 0.01) in a multivariate linear regression analysis.
  
  
  CONCLUSIONS
  FFM index was weakly associated with peak exercise IC in COPD patients. However, it ceased to be an independent predictor when corrected for expiratory airflow limitation (FEV₁) and lung hyperinflation at rest (rest IC).
authors.affiliation: Postgraduate Program in Respiratory Sciences, Federal University of Rio Grande do Sul (UFRGS), Novo Hamburgo, Brazil.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Silveira
authors.forename: Paulo José Zimermann
authors.initials: PJ
authors.lastname: Teixeira
authors.forename: Cassia C
authors.initials: CC
authors.lastname: da Costa
authors.forename: Rafael M
authors.initials: RM
authors.lastname: de Souza
authors.forename: Pietro Krauspenhar
authors.initials: PK
authors.lastname: Merola
authors.forename: Caroline
authors.initials: C
authors.lastname: Colombo
authors.forename: Renata D
authors.initials: RD
authors.lastname: Marques
authors.forename: Danilo C
authors.initials: DC
authors.lastname: Berton
mesh_terms: D000368:Aged; D017097:Electric Impedance; D005080:Exercise Test / Q000379:methods; D017079:Exercise Tolerance; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007320:Inspiratory Capacity; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000503:physiopathology / Q000534:rehabilitation; D012123:Pulmonary Ventilation; D012146:Rest; D012720:Severity of Illness Index
keywords: chronic obstructive pulmonary disease; exercise and pulmonary rehabilitation; respiratory function test; respiratory structure and function; ventilation