title: Depression, heart rate variability, and exercise training in dialysis patients.
abstract: BACKGROUND
  Functional limitations, altered cardiac autonomic activity, and psychological distress are known disorders in chronic hemodialysis (HD) patients, relating to increased morbidity and mortality. The aim of this study was to examine the influence of an exercise training program on emotional parameters and heart rate variability (HRV) indices, as well as to determine whether emotional stress contributes to autonomic dysfunction in these patients.
  
  
  METHODS
  Forty-four HD patients were randomly assigned into group A (24 patients, aged 46.3+/-11.2 years), who participated in a 1-year intradialytic exercise training program and group B (20 patients, aged 45.8+/-10.8 years), who were used as controls. At baseline and a year after, measures of HRV were obtained for the estimation of standard deviation of RR intervals, the mean square successive differences, percentage of RR intervals differing by more than 50 ms from the preceding RR interval (pNN50), and low to high frequency components. Emotional parameters (Beck Depression Inventory - BDI and Hospital Anxiety and Depression Scale - HADS) were also assessed by validated questionnaires. Moreover, all patients performed a spiroergometric study for the estimation of VO2peak.
  
  
  RESULTS
  At baseline, all measurements were similar in the two groups and remained almost unchanged after a year in group B. After a year of training, VO2peak increased from 16.79+/-5.24 to 22.33+/-4.90 ml/kg per min (P<0.001) in group A. Trained patients also showed an increase in standard deviation of RR intervals by 58.8% (P<0.001), the mean square successive differences by 68.1% (P<0.001), pNN50 by 23.5% (P<0.001), and a low to high frequency ratio by 17.3% (P<0.001). Finally, at the end of the study, group A showed a decrease in BDI score by 34.5% (P<0.001) and HADS by 23.9% (P<0.001). Canonical correlation revealed significant inverse correlation among depression (in BDI and HADS) and HRV indices before and after exercise training.
  
  
  CONCLUSIONS
  Cardiac autonomic modulation seemed to be sensitive to the experience of persistent depression in HD patients. Significantly, exercise training reduced emotional distress and concomitantly improved HRV.
authors.affiliation: Sports Medicine Laboratory, TEFAA, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Evangelia
authors.initials: E
authors.lastname: Kouidi
authors.forename: Vassilis
authors.initials: V
authors.lastname: Karagiannis
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Grekas
authors.forename: Apostolos
authors.initials: A
authors.lastname: Iakovides
authors.forename: George
authors.initials: G
authors.lastname: Kaprinis
authors.forename: Achilleas
authors.initials: A
authors.lastname: Tourkantonis
authors.forename: Asterios
authors.initials: A
authors.lastname: Deligiannis
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology*; D016009:Chi-Square Distribution; D003863:Depression / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D005080:Exercise Test; D005081:Exercise Therapy; D005260:Female; D006115:Greece; D006339:Heart Rate; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications / Q000503:physiopathology / Q000523:psychology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D011569:Psychiatric Status Rating Scales; D006435:Renal Dialysis / Q000009:adverse effects / Q000523:psychology*; D013147:Spirometry; D013315:Stress, Psychological / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D011795:Surveys and Questionnaires; D013997:Time Factors; D016896:Treatment Outcome