title: The role of deconditioning in the end-stage renal disease myopathy: physical exercise improves altered resting muscle oxygen consumption.
abstract: BACKGROUND
  Skeletal muscle dysfunction and poor exercise tolerance are hallmarks of end-stage renal disease (ESRD). Noninvasively measured (near-infrared spectroscopy, NIRS) resting muscle oxygen consumption (rmVO2) is a biomarker of muscle dysfunction, which can be applied to study the severity and the reversibility of ESRD myopathy. We tested the hypothesis that deconditioning is a relevant factor in ESRD myopathy.
  
  
  METHODS
  The whole dialysis population (n = 59) of two of the eight centers participating into the EXCITE study (ClinicalTrials.gov NCT01255969), a randomized trial evaluating the effect of a home-based exercise program on the functional capacity of these patients was studied. Thirty-one patients were in the active arm (exercise group) and 28 in the control arm (no intervention). Normative data for rmVO2 were obtained from a group of 19 healthy subjects.
  
  
  RESULTS
  rmVO2 was twice higher (p < 0.001) in ESRDs patients (0.083 ± 0.034 ml/100 g/min) than in healthy subjects (0.041 ± 0.020 ml/100 g/min) indicating substantial skeletal muscle dysfunction in ESRD. rmVO2 correlated with resting heart rate (r = 0.34, p = 0.009) but was independent of age, dialysis vintage, biochemical, vascular and nutrition parameters. After the 6-month exercise program, rmVO2 reduced to 0.064 ± 0.024 ml/100 g/min (-23%, p < 0.001) in the exercise group indicating that skeletal muscle dysfunction is largely reversible but remained identical in the control group (0.082 ± 0.032 to 0.082 ± 0.031 ml/100 g/min).
  
  
  CONCLUSIONS
  Deconditioning has a major role in ESRD myopathy. rmVO2 is a marker of physical deconditioning and has the potential for monitoring re-conditioning programs based on physical exercise in the ESRD population.
authors.affiliation: Department of Biomedical Sciences and Surgical Specialties, Section of Sport Sciences, University of Ferrara, Ferrara, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Manfredini
authors.forename: Nicola
authors.initials: N
authors.lastname: Lamberti
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Malagoni
authors.forename: Michele
authors.initials: M
authors.lastname: Felisatti
authors.forename: Alessandro
authors.initials: A
authors.lastname: Zuccalà
authors.forename: Claudia
authors.initials: C
authors.lastname: Torino
authors.forename: Giovanni
authors.initials: G
authors.lastname: Tripepi
authors.forename: Luigi
authors.initials: L
authors.lastname: Catizone
authors.forename: Francesca
authors.initials: F
authors.lastname: Mallamaci
authors.forename: Carmine
authors.initials: C
authors.lastname: Zoccali
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D018493:Cardiovascular Deconditioning; D015444:Exercise; D005080:Exercise Test; D005081:Exercise Therapy; D017079:Exercise Tolerance; D005260:Female; D006339:Heart Rate; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism*; D009135:Muscular Diseases / Q000209:etiology / Q000628:therapy*; D010101:Oxygen Consumption; D010809:Physical Fitness; D006435:Renal Dialysis; D019265:Spectroscopy, Near-Infrared; D016896:Treatment Outcome