title: Intra-dialytic training accelerates oxygen uptake kinetics in hemodialysis patients.
abstract: BACKGROUND
  End-stage renal disease is associated with several hemodynamic and peripheral muscle abnormalities that could slow the rate of change in oxygen uptake ([Formula: see text]O2) at the onset and at the end of exercise. This study was performed to determine whether an intra-dialytic aerobic training program would speed [Formula: see text]O2 kinetics at the transition to and from moderate and high-intensity exercise.
  
  
  METHODS
  This study was a randomized controlled trial.
  
  
  METHODS
  Twenty-four patients with end-stage renal disease (14 females; 47.0 ± 11.9 years) were randomly assigned to either 12-week cycle ergometer-based training at moderate exertion or a similar control period. At initial and final evaluations, patients underwent 6 min moderate and high-intensity tests to exercise intolerance (Tlim).
  
  
  RESULTS
  Training improved Tlim by ∼90% (median (inter-quartile range) = 232 (59) s to 445 (451) s, p < 0.05); in contrast, Tlim decreased by ∼30% in controls (291 (134) s to 202 (131) s). [Formula: see text]O2 kinetics at the onset of moderate-intensity exercise were significantly accelerated with training leading to lower oxygen (O2) deficit (mean ± standard deviation (SD) = 3.2 ± 1.3 l vs 2.3 ± 1.2 l). Similar positive effects were found at the high-intensity test either at the onset of, or recovery from, exercise (p < 0.05). "Excess" [Formula: see text]O2 at the high-intensity test was also lessened with training. Changes in Tlim correlated with faster [Formula: see text]O2 kinetics and lower "excess" [Formula: see text]O2 (Spearman's ρ = -0.56 and -0.75, respectively; p < 0.01).
  
  
  CONCLUSIONS
  A symptom-targeted intra-dialytic training program improved sub-maximal aerobic metabolism and endurance exercise capacity. [Formula: see text]O2 kinetics are valuable in providing relatively effort-independent information on the efficacy of exercise interventions in this patient population.
authors.affiliation: Division of Pulmonology, Federal University of Juiz de Fora, Brazil NIEPEN, Federal University of Juiz de Fora, Brazil mayconreboredo@yahoo.com.br.
authors.forename: Maycon M
authors.initials: MM
authors.lastname: Reboredo
authors.affiliation: Division of Respiratory and Critical Care Medicine, Queen's University, Canada.
authors.forename: J Alberto
authors.initials: JA
authors.lastname: Neder
authors.affiliation: Division of Pulmonology, Federal University of Juiz de Fora, Brazil.
authors.forename: Bruno V
authors.initials: BV
authors.lastname: Pinheiro
authors.affiliation: NIEPEN, Federal University of Juiz de Fora, Brazil.
authors.forename: Diane Mn
authors.initials: DM
authors.lastname: Henrique
authors.affiliation: NIEPEN, Federal University of Juiz de Fora, Brazil.
authors.forename: Julio Cm
authors.initials: JC
authors.lastname: Lovisi
authors.affiliation: NIEPEN, Federal University of Juiz de Fora, Brazil.
authors.forename: Rogério B
authors.initials: RB
authors.lastname: Paula
mesh_terms: D000328:Adult; D001938:Brazil; D005080:Exercise Test; D005081:Exercise Therapy; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000175:diagnosis / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000503:physiopathology; D010101:Oxygen Consumption; D006435:Renal Dialysis; D016896:Treatment Outcome
keywords: Aerobic exercise; end-stage renal disease; exercise tolerance; hemodialysis; oxygen uptake kinetics