title: Neuromuscular electrical stimulation improves exercise tolerance in chronic obstructive pulmonary disease patients with better preserved fat-free mass.
abstract: BACKGROUND
  High-frequency neuromuscular electrical stimulation increases exercise tolerance in patients with advanced chronic obstructive pulmonary disease (COPD patients). However, it is conceivable that its benefits are more prominent in patients with better-preserved peripheral muscle function and structure.
  
  
  OBJECTIVE
  To investigate the effects of high-frequency neuromuscular electrical stimulation in COPD patients with better-preserved peripheral muscle function.
  
  
  METHODS
  Prospective and cross-over study.
  
  
  METHODS
  Thirty COPD patients were randomly assigned to either home-based, high-frequency neuromuscular electrical stimulation or sham stimulation for six weeks. The training intensity was adjusted according to each subject's tolerance. Fat-free mass, isometric strength, six-minute walking distance and time to exercise intolerance (Tlim) were assessed.
  
  
  RESULTS
  Thirteen (46.4%) patients responded to high-frequency neuromuscular electrical stimulation; that is, they had a post/pre Δ Tlim >10% after stimulation (unimproved after sham stimulation). Responders had a higher baseline fat-free mass and six-minute walking distance than their seventeen (53.6%) non-responding counterparts. Responders trained at higher stimulation intensities; their mean amplitude of stimulation during training was significantly related to their fat-free mass (r = 0.65; p<0.01). Logistic regression revealed that fat-free mass was the single independent predictor of Tlim improvement (odds ratio [95% CI] = 1.15 [1.04-1.26]; p<0.05).
  
  
  CONCLUSIONS
  We conclude that high-frequency neuromuscular electrical stimulation improved the exercise capacity of COPD patients with better-preserved fat-free mass because they tolerated higher training stimulus levels. These data suggest that early training with high-frequency neuromuscular electrical stimulation before tissue wasting begins might enhance exercise tolerance in patients with less advanced COPD.
authors.affiliation: Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Respiratory Division, Department of Medicine, Federal University of São Paulo, São Paulo, Brazil.
authors.forename: Lara Maris
authors.initials: LM
authors.lastname: Nápolis
authors.forename: Simone
authors.initials: S
authors.lastname: Dal Corso
authors.forename: José Alberto
authors.initials: JA
authors.lastname: Neder
authors.forename: Carla
authors.initials: C
authors.lastname: Malaguti
authors.forename: Ana Cristina Oliveira
authors.initials: AC
authors.lastname: Gimenes
authors.forename: Luiz Eduardo
authors.initials: LE
authors.lastname: Nery
mesh_terms: D000368:Aged; D001823:Body Composition / Q000502:physiology*; D018592:Cross-Over Studies; D004599:Electric Stimulation Therapy / Q000379:methods*; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology* / Q000534:rehabilitation; D012129:Respiratory Function Tests; D018709:Statistics, Nonparametric; D013997:Time Factors