title: Improvement of heart rate variability after exercise training and its predictors in COPD.
abstract: BACKGROUND
  Current literature lacks solid evidence on the improvement of heart rate variability (HRV) after exercise training in patients with COPD.
  
  
  OBJECTIVE
  We aimed to investigate changes in HRV after two exercise training programs in patients with COPD and to investigate the determinants of these eventual changes.
  
  
  METHODS
  Forty patients with COPD (FEV(1) 39 ± 13%pred) were randomized into high (n = 20) or low (n = 20) intensity exercise training (3-month duration), and had their HRV assessed by the head-up tilt test before and after either protocols. Baseline spirometry, level of daily physical activity, exercise capacity, body composition, functional status, health-related quality of life and muscle force were also assessed to investigate the determinants of improvement in HRV after the training program.
  
  
  RESULTS
  There was a significant improvement in HRV only after the high-intensity protocol (pre versus post; SDNN 29 ± 15 ms versus 36 ± 19 ms; rMSSD 22 ± 14 ms versus 28 ± 22 ms; p < 0.05 for both). Higher values of biceps brachialis strength, time spent walking in daily life and SDNN at baseline were determinants of improvement in HRV after the training program.
  
  
  CONCLUSIONS
  High-intensity exercise training improves HRV at rest and during orthostatic stimulus in patients with COPD. Better baseline total HRV, muscle force and daily physical activity level are predictors of HRV improvements after the training program.
authors.affiliation: Laboratório de Pesquisa em Fisioterapia Pulmonar, Departamento de Fisioterapia, Universidade Estadual de Londrina, Londrina, Paraná, Brazil.
authors.forename: Carlos Augusto
authors.initials: CA
authors.lastname: Camillo
authors.forename: Viviane de Moraes
authors.initials: Vde M
authors.lastname: Laburu
authors.forename: Nicole Soriano
authors.initials: NS
authors.lastname: Gonçalves
authors.forename: Vinícius
authors.initials: V
authors.lastname: Cavalheri
authors.forename: Fernanda Priore
authors.initials: FP
authors.lastname: Tomasi
authors.forename: Nidia Aparecida
authors.initials: NA
authors.lastname: Hernandes
authors.forename: Dionei
authors.initials: D
authors.lastname: Ramos
authors.forename: Luiz Carlos
authors.initials: LC
authors.lastname: Marquez Vanderlei
authors.forename: Ercy Mara
authors.initials: EM
authors.lastname: Cipulo Ramos
authors.forename: Vanessa Suziane
authors.initials: VS
authors.lastname: Probst
authors.forename: Fabio
authors.initials: F
authors.lastname: Pitta
mesh_terms: D000368:Aged; D001341:Autonomic Nervous System / Q000503:physiopathology*; D001823:Body Composition / Q000502:physiology; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D010807:Physical Endurance / Q000502:physiology*; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology* / Q000534:rehabilitation; D055070:Resistance Training / Q000379:methods*; D012146:Rest / Q000502:physiology; D013147:Spirometry