title: High-intensity interval exercise improves vagal tone and decreases arrhythmias in chronic heart failure.
abstract: OBJECTIVE
  Autonomic dysfunction including sympathetic activation and vagal withdrawal has been reported in patients with chronic heart failure (CHF). We tested the hypotheses that high-intensity interval exercise (HIIE) in CHF patients would enhance vagal modulation and thus decrease arrhythmic events.
  
  
  METHODS
  Eighteen CHF patients underwent a baseline assessment (CON) and were then randomized to a single session of HIIE and to an isocaloric moderate-intensity continuous exercise (MICE). We evaluated the HR, HR variability parameters, and arrhythmic events by 24-h Holter ECG recordings after HIIE, MICE, and CON sessions.
  
  
  RESULTS
  We found that HR was significantly decreased after HIIE (68 ± 3 bpm, P < 0.01) when compared with CON and MICE values (71.1 ± 2 and 69 ± 3 bpm, respectively). HIIE led to a significant increase in normalized high-frequency power (35.95% ± 2.83% vs 31.56% ± 1.93% and 24.61% ± 2.62% for CON and MICE, respectively, P < 0.01). Both exercise conditions were associated with an increase in very low frequency power comparative to CON. After HIIE, premature ventricular contractions were significantly decreased (531 ± 338 vs 1007 ± 693 and 1671 ± 1604 for CON and MICE, respectively, P < 0.01). An association was found between the changes in premature ventricular contraction and the changes in low-frequency/high-frequency ratio (r = 0.66, P < 0.01) in patients exposed to HIIE.
  
  
  CONCLUSIONS
  We demonstrate that a single session of HIIE improves autonomic profile of CHF patients, leading to significant reductions of HR and arrhythmic events in a 24-h posttraining period. Cardioprotective effects of HIIE in CHF patients need to be confirmed in a larger study population and on a long-term basis.
authors.affiliation: 1Institute of Cardiovascular and Metabolic Diseases, National Institute of Health and Medical Research (INSERM), UMR-1048, Toulouse, FRANCE; 2Clinic of Saint-Orens, Cardiovascular and Pulmonary Rehabilitation Center, Saint-Orens-de-Gameville, FRANCE; 3University of Toulouse III: Paul Sabatier, Toulouse, FRANCE; 4Department of Rehabilitation, Toulouse University Hospital, Toulouse, FRANCE; 5Department of Clinical Pharmacology, Toulouse University Hospital, Toulouse, FRANCE; 6University Hospital of Geneva, Geneva, SWITZERLAND; and 7Faculty of Sports Sciences and MOVE Laboratory (EA 6314), University of Poitiers, Poitiers, FRANCE.
authors.forename: Thibaut
authors.initials: T
authors.lastname: Guiraud
authors.forename: Marc
authors.initials: M
authors.lastname: Labrunee
authors.forename: Kevin
authors.initials: K
authors.lastname: Gaucher-Cazalis
authors.forename: Fabien
authors.initials: F
authors.lastname: Despas
authors.forename: Philippe
authors.initials: P
authors.lastname: Meyer
authors.forename: Laurent
authors.initials: L
authors.lastname: Bosquet
authors.forename: Celine
authors.initials: C
authors.lastname: Gales
authors.forename: Angelica
authors.initials: A
authors.lastname: Vaccaro
authors.forename: Marc
authors.initials: M
authors.lastname: Bousquet
authors.forename: Michel
authors.initials: M
authors.lastname: Galinier
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Sénard
authors.forename: Atul
authors.initials: A
authors.lastname: Pathak
mesh_terms: D000328:Adult; D000368:Aged; D001145:Arrhythmias, Cardiac / Q000150:complications / Q000503:physiopathology*; D001341:Autonomic Nervous System / Q000503:physiopathology*; D002908:Chronic Disease; D018592:Cross-Over Studies; D015716:Electrocardiography, Ambulatory; D015444:Exercise / Q000502:physiology*; D005260:Female; D006333:Heart Failure / Q000150:complications / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction