title: Acute responses to intermittent and continuous exercise in heart failure patients.
abstract: BACKGROUND
  The purpose of this study was to compare cardiopulmonary responses, exercise adherence, tolerance, and safety of optimized high-intensity interval exercise (HIIE) compared with moderate-intensity continuous exercise (MICE) in patients with heart failure and reduced ejection fraction (HFREF).
  
  
  METHODS
  Twenty patients with HFREF (aged 61 ± 9.9 years) were randomly assigned to HIIE corresponding to 2 × 8 minutes of 30-second intervals at 100% of peak power output and 30-second passive recovery intervals and to a 22-minute MICE corresponding to 60% of peak power output. Gas exchange, electrocardiogram, and blood pressure were measured continuously. Cardiac troponin T (cTnT), C-reactive protein (CRP), and brain natriuretic peptide (BNP) were measured before, 20 minutes after, and 24 hours after HIIE and MICE.
  
  
  RESULTS
  Cardiopulmonary responses did not differ between MICE and HIIE. Higher exercise adherence and efficiency were observed on HIIE with a similar perceived exertion and time spent above 90% of peak oxygen consumption compared with MICE. Neither HIIE nor MICE caused any significant arrhythmias or increased CRP, BNP, or cTnT.
  
  
  CONCLUSIONS
  Compared with MICE, HIIE demonstrated a higher exercise adherence and was well tolerated in patients with HFREF, while still providing a high-level physiological stimulus and leaving indices of inflammation (CRP), myocardial dysfunction (BNP), and myocardial necrosis (cTnT) unaffected.
authors.affiliation: Cardiovascular Prevention and Rehabilitation Centre (Centre ÉPIC), Montreal Heart Institute, University of Montreal, Montreal, Québec, Canada.
authors.forename: Eve
authors.initials: E
authors.lastname: Normandin
authors.forename: Anil
authors.initials: A
authors.lastname: Nigam
authors.forename: Philippe
authors.initials: P
authors.lastname: Meyer
authors.forename: Martin
authors.initials: M
authors.lastname: Juneau
authors.forename: Thibaut
authors.initials: T
authors.lastname: Guiraud
authors.forename: Laurent
authors.initials: L
authors.lastname: Bosquet
authors.forename: Asmaa
authors.initials: A
authors.lastname: Mansour
authors.forename: Mathieu
authors.initials: M
authors.lastname: Gayda
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D001794:Blood Pressure; D002097:C-Reactive Protein / Q000378:metabolism*; D004562:Electrocardiography; D015444:Exercise; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006333:Heart Failure / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010101:Oxygen Consumption; D011659:Pulmonary Gas Exchange; D013318:Stroke Volume; D020107:Troponin T / Q000097:blood*
chemical_list: D015415:Biomarkers; D020107:Troponin T; D020097:Natriuretic Peptide, Brain; D002097:C-Reactive Protein