title: Interaction between intradialytic exercise and hemodialysis adequacy.
abstract: OBJECTIVE
  According to mathematical modeling, intradialytic exercise of sufficient intensity and duration implemented in the second half of dialysis should be as efficacious as increasing dialysis time for dialysis adequacy. This assumption has not been tested in vivo.
  
  
  METHODS
  In this controlled trial, 11 hemodialysis (HD) patients (mean (SD) age 56 (13) years) were recruited. Each patient completed three trial arms in a randomized order: routine care (CONT), increased HD time of 30 min (TIME), and intradialytic exercise (EXER), 60 min of cycling at 90% of the lactate threshold in the last 90 min of HD. The primary outcome was eKt/Vurea. Secondary outcomes included reduction and rebound ratios of urea, creatinine, phosphate and β2-microglobulin. Outcomes were calculated from blood sampling collected pre-, post- and 30 min post-HD and confirmed with dialysate sampling.
  
  
  RESULTS
  Exercise was not as efficacious as increased HD time for eKt/Vurea (EXER vs. CONT, mean change (95% CI): 0.03 (-0.05 to 0.12); TIME vs. CONT: 0.15 (0.05-0.26)). Exercise was less efficacious at improving reduction ratios of urea and creatinine. However, exercise was more efficacious than increased dialysis time for phosphate reduction ratio (EXER vs. CONT: 8.6% (0.5-16.7); TIME vs. CONT: 5.0% (-1.0 to 11.1)).
  
  
  CONCLUSIONS
  This study utilized a rigorously controlled in vivo design to test mathematical models and assumptions regarding dialysis adequacy. Intradialytic exercise towards the end of HD cannot replace the prescription of increased HD time for dialysis adequacy, but may be an adjunctive therapy for serum phosphate control.
authors.affiliation: College of Health and Behavioural Sciences, Bangor University, Bangor, UK.
authors.forename: Danielle L
authors.initials: DL
authors.lastname: Kirkman
authors.forename: Lisa D
authors.initials: LD
authors.lastname: Roberts
authors.forename: Marten
authors.initials: M
authors.lastname: Kelm
authors.forename: Jürgen
authors.initials: J
authors.lastname: Wagner
authors.forename: Mahdi M
authors.initials: MM
authors.lastname: Jibani
authors.forename: Jamie H
authors.initials: JH
authors.lastname: Macdonald
mesh_terms: D000328:Adult; D000368:Aged; D003404:Creatinine / Q000378:metabolism; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000628:therapy*; D007773:Lactates / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D010710:Phosphates / Q000097:blood / Q000378:metabolism; D006435:Renal Dialysis / Q000379:methods*; D013997:Time Factors; D014508:Urea / Q000378:metabolism; D001613:beta 2-Microglobulin / Q000378:metabolism
chemical_list: D007773:Lactates; D010710:Phosphates; D001613:beta 2-Microglobulin; D014508:Urea; D003404:Creatinine