title: Aerobic exercise improves fitness and heart rate variability after an implantable cardioverter defibrillator.
abstract: OBJECTIVE
  The purpose of this study was to determine the effects of an 8-week aerobic exercise program on (1) cardiopulmonary fitness and activity, (2) heart rate variability (HRV), (3) health outcomes, and (4) high sensitivity C-reactive protein (hsCRP) in survivors of sudden cardiac arrest who have an implantable cardioverter-defibrillator (ICD).
  
  
  METHODS
  A single group pre-post exercise program with a 6-month follow-up was used in 10 ICD recipients. The exercise intervention consisted of supervised outpatient aerobic exercise 3 hours per week plus home walking 2 hours per week for 8 weeks. Patients were told to walk for 30 minutes on all or most days of the week for the remaining 4 months. Measures were taken at baseline, 8 weeks, and 24 weeks.
  
  
  RESULTS
  Cardiopulmonary fitness (exercise time, oxygen uptake at anaerobic threshold, metabolic equivalents), HRV (standard deviation of all R-R intervals, root-mean square of successive differences, high-frequency power), health outcomes (Short Form-12 physical and mental health, anxiety, depression), and hsCRP were improved after 8 weeks of exercise. Sustained effects of the exercise program were noted in daily activity (RT3 vector magnitude per minute), HRV (standard deviation 5-minute segments, root-mean square of successive differences, percent R-R change by 50 milliseconds high frequency power), and health outcomes (Short Form-12 physical health).
  
  
  CONCLUSIONS
  Sudden cardiac arrest survivors who have an ICD are a group of cardiac patients who can potentially benefit the most from exercise by stabilizing autonomic function and reducing the incidence of arrhythmias. Although causal conclusions cannot be drawn from this study, further testing of aerobic exercise interventions in this population appears warranted.
authors.affiliation: Department of Biobehavioral Nursing and Health Systems, School of Nursing, University of Washington, Seattle, WA 98195, USA. cindyd@u.washington.edu
authors.forename: Cynthia M
authors.initials: CM
authors.lastname: Dougherty
authors.forename: Robb
authors.initials: R
authors.lastname: Glenny
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Kudenchuk
mesh_terms: D016757:Death, Sudden, Cardiac; D017147:Defibrillators, Implantable; D005081:Exercise Therapy; D005260:Female; D006323:Heart Arrest / Q000534:rehabilitation / Q000628:therapy*; D006339:Heart Rate; D006801:Humans; D008297:Male; D055686:Metabolic Equivalent; D008875:Middle Aged; D010101:Oxygen Consumption; D010809:Physical Fitness
references.citation: Med Sci Sports Exerc. 1999 Jun;31(6):908-12
references.pmid: 10378921
references.citation: Med Sci Sports Exerc. 2000 Sep;32(9 Suppl):S489-97
references.pmid: 10993419
references.citation: Circulation. 1994 Feb;89(2):548-52
references.pmid: 8313542
references.citation: Cardiol Clin. 1992 Aug;10(3):487-98
references.pmid: 1504980
references.citation: Eur Heart J. 1996 Apr;17(4):532-8
references.pmid: 8733085
references.citation: Am J Cardiol. 1987 Feb 1;59(4):256-62
references.pmid: 3812275
references.citation: Circulation. 1996 Mar 1;93(5):1043-65
references.pmid: 8598068
references.citation: Eur Heart J. 1995 Apr;16(4):490-5
references.pmid: 7671894
references.citation: J Chronic Dis. 1987;40(6):473-80
references.pmid: 3298292
references.citation: Circulation. 1984 Aug;70(2):184-91
references.pmid: 6733874