title: Physical activity patterns in chronic hemodialysis patients: comparison of dialysis and nondialysis days.
abstract: OBJECTIVE
  To determine physical activity patterns in chronic hemodialysis patients with a specific emphasis on the difference between dialysis and nondialysis days. Design A cross-sectional single-center study.
  
  
  METHODS
  Vanderbilt University Outpatient Dialysis Unit.
  
  
  METHODS
  Twenty current chronic hemodialysis patients: 10 male, 10 female; 15 black, 5 white; mean age, 50.1 +/- 9.9 years; height, 164.5 +/- 10.9 cm; weight, 82.5 +/- 15.4 kg; length on dialysis, 57.3 +/- 45.3 months.
  
  
  METHODS
  Minute-by-minute physical activity was assessed over a 7-day period using a triaxial accelerometer, which consists of raw numbers or counts calculated by the 3 axes of the accelerometer (PA counts). PA counts were extrapolated on a daily and hourly basis. Physical functioning tests included: sit-to-stand, 6-minute walk, and 1-repetition maximal leg press exercise. Laboratory values for serum concentrations of albumin, prealbumin, C-reactive protein, and cholesterol were also collected.
  
  
  METHODS
  PA counts.
  
  
  RESULTS
  Total PA counts were significantly lower on dialysis days when compared with nondialysis days (128,279 +/- 74,009 versus 168,744 +/- 95,168, respectively, P = .025). The average PA counts during the 4-hour dialysis time period were significantly lower on dialysis days when compared with nondialysis days (3,086 +/- 3,749 versus 11,070 +/- 7,695, respectively, P = .001). At postdialysis hours 1 and 2, PA counts on dialysis days were significantly higher than on nondialysis days (11,410 +/- 5,340 versus 9,082 +/- 6,646, P = .008, and 14,048 +/- 9,728 versus 8,662 +/- 6,433, P = .016, respectively). By postdialysis hour 4, PA counts on dialysis days had significantly decreased when compared with nondialysis days (6,068 +/- 6,268 versus 10,512 +/- 7,420 PA counts, P = .01, respectively). From postdialysis hours 5 to 20, there was no significant difference in PA counts between dialysis and nondialysis days.
  
  
  CONCLUSIONS
  This study shows that physical activity is lower on dialysis days when compared with nondialysis days, and this decrease is caused by the lack of activity during the 4-hour hemodialysis procedure. New behavior modification strategies involving physical activity, both during hemodialysis and on nondialysis days, must be examined in this patient population.
authors.affiliation: Department of Medicine, Division of Nephrology, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: Karen M
authors.initials: KM
authors.lastname: Majchrzak
authors.forename: Lara B
authors.initials: LB
authors.lastname: Pupim
authors.forename: Kong
authors.initials: K
authors.lastname: Chen
authors.forename: Cathi J
authors.initials: CJ
authors.lastname: Martin
authors.forename: Sheila
authors.initials: S
authors.lastname: Gaffney
authors.forename: Jane H
authors.initials: JH
authors.lastname: Greene
authors.forename: T Alp
authors.initials: TA
authors.lastname: Ikizler
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D001823:Body Composition; D002097:C-Reactive Protein / Q000032:analysis; D002784:Cholesterol / Q000097:blood; D003430:Cross-Sectional Studies; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D011228:Prealbumin / Q000032:analysis; D006435:Renal Dialysis; D012709:Serum Albumin / Q000032:analysis; D013997:Time Factors
chemical_list: D011228:Prealbumin; D012709:Serum Albumin; D002097:C-Reactive Protein; D002784:Cholesterol