title: Effects of inspiratory muscle training on autonomic activity, endothelial vasodilator function, and N-terminal pro-brain natriuretic peptide levels in chronic heart failure.
abstract: OBJECTIVE
  To assess the effects of inspiratory muscle training (IMT) on autonomic activity, endothelial function, and N-terminal pro-brain natriuretic peptide (NT-proBNP) levels in patients with chronic heart failure.
  
  
  METHODS
  Using age- and sex-matched controlled study, 23 patients (mean left ventricular ejection fraction 29 +/- 2%) were assigned to either a high-intensity training group (n = 14), New York Heart Association (NYHA) class II (n = 9)/III (n = 5), or a low-intensity training group (n = 9), NYHA class II (n = 6)/III (n = 3), exercising at 60% and 15% of sustained maximum inspiratory pressure (SPImax), respectively, 3 times per week for 10 weeks. Before and following IMT, patients underwent cardiopulmonary exercise testing and dyspnea evaluation on exertion. Sympathovagal balance was assessed by heart rate variability (HRV) from 24-hour electrocardiogram and endothelial function, using venous occlusion plethysmography. Serum levels of NT-proBNP were determined.
  
  
  RESULTS
  High-intensity training group improved maximum inspiratory pressure (PImax, 105.4 +/- 5.3 vs 79.1 +/- 5 cm H2O, P = .001), SPImax (511 +/- 42 vs 308 +/- 28 cm H2O/sec/10, P = .001), peak oxygen consumption (19 +/- 1.2 vs 17.1 +/- 0.7 mL.kgmin, P = .01) and dyspnea (17.6 +/- 0.2 vs 18.1 +/- 0.1, P = .02). Endothelium-dependent vasodilation, HRV, and NT-proBNP levels were not altered. Low-intensity training group increased only the PImax (97.6 +/- 11.3 vs 84.2 +/- 8.7 cm H2O, P = .03).
  
  
  CONCLUSIONS
  Improvement in dyspnea and exercise tolerance after IMT were not associated with changes in markers of HRV, endothelial function, and NT-proBNP in patients with mild to moderate chronic heart failure. Further studies on the effects of IMT in advanced heart failure would be worthwhile.
authors: Onassis Cardiac Surgery Center, Athens, Greece. ylaoutaris@yahoo.gr
authors: Ioannis D
authors: ID
authors: Laoutaris
authors: Athanasios
authors: A
authors: Dritsas
authors: Margaret D
authors: MD
authors: Brown
authors: Athanassios
authors: A
authors: Manginas
authors: Manolis S
authors: MS
authors: Kallistratos
authors: Antigoni
authors: A
authors: Chaidaroglou
authors: Dimitrios
authors: D
authors: Degiannis
authors: Peter A
authors: PA
authors: Alivizatos
authors: Dennis V
authors: DV
authors: Cokkinos
mesh_terms: D009320:Atrial Natriuretic Factor / Q000097:blood*; D001341:Autonomic Nervous System / Q000503:physiopathology; D001945:Breathing Exercises; D004730:Endothelium, Vascular / Q000503:physiopathology*; D017079:Exercise Tolerance; D005542:Forearm / Q000098:blood supply; D006333:Heart Failure / Q000503:physiopathology* / Q000534:rehabilitation; D006339:Heart Rate; D006801:Humans; D010991:Plethysmography; D011498:Protein Precursors / Q000097:blood*; D012039:Regional Blood Flow; D012129:Respiratory Function Tests; D012132:Respiratory Muscles / Q000503:physiopathology
chemical_list: C099254:N-terminal proatrial natriuretic peptide; D011498:Protein Precursors; D009320:Atrial Natriuretic Factor