title: Fat metabolism during exercise in patients with mitochondrial disease.
abstract: OBJECTIVE
  To determine whether patients with defects of the respiratory chain have metabolic adaptations that promote a preferential use of fats or carbohydrates, similar to what is observed in metabolic myopathies affecting glycolysis or fat oxidation.
  
  
  METHODS
  Causation and case-control study. Fat metabolism was determined by means of indirect calorimetry and stable isotope technique in patients and healthy subjects. Patients carried various types and loads (mean [SE], 72% [5%]) of mitochondrial DNA (mtDNA) mutations in skeletal muscle. All subjects exercised at the same absolute workload (mean [SE], 65 [10] W), corresponding to 72% (in patients) and 30% (in healthy subjects) of maximum oxygen consumption.
  
  
  METHODS
  Neuromuscular research unit.
  
  
  METHODS
  Ten patients with mtDNA mutations and 10 sex-matched healthy subjects.
  
  
  METHODS
  Fat turnover, plasma concentrations of palmitate and total free fatty acids, glucose mobilization, and total carbohydrate oxidation.
  
  
  RESULTS
  Fat turnover and plasma concentrations of palmitate and total free fatty acids were similar in patients and healthy subjects at rest and during exercise. In line with the higher relative workload of the patients, glucose mobilization and total carbohydrate oxidation were higher in the patients compared with the healthy subjects.
  
  
  CONCLUSIONS
  During moderate-intensity exercise, the balance between fat and carbohydrate use in patients with mtDNA mutations matches that seen in healthy subjects, indicating that manipulating dietary fat and carbohydrate content is not a feasible therapeutic option to improve exercise intolerance in these disorders.
authors.affiliation: Department of Neurology and Copenhagen Muscle Research Center, University of Copenhagen, Rigshospitalet, Denmark.
authors.forename: Tina Dysgaard
authors.initials: TD
authors.lastname: Jeppesen
authors.forename: Mette Cathrine
authors.initials: MC
authors.lastname: Orngreen
authors.forename: Gerrit
authors.initials: G
authors.lastname: van Hall
authors.forename: Ronald G
authors.initials: RG
authors.lastname: Haller
authors.forename: John
authors.initials: J
authors.lastname: Vissing
mesh_terms: D000328:Adult; D050260:Carbohydrate Metabolism; D016022:Case-Control Studies; D004579:Electron Transport; D004837:Epinephrine / Q000097:blood; D015444:Exercise / Q000502:physiology*; D005227:Fatty Acids / Q000097:blood*; D005260:Female; D005947:Glucose / Q000378:metabolism; D006728:Hormones / Q000097:blood; D006801:Humans; D007328:Insulin / Q000097:blood; D050356:Lipid Metabolism / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D028361:Mitochondrial Diseases / Q000097:blood / Q000503:physiopathology* / Q000534:rehabilitation*; D018482:Muscle, Skeletal; D009638:Norepinephrine / Q000097:blood; D010101:Oxygen Consumption; D019308:Palmitic Acid / Q000097:blood
chemical_list: D005227:Fatty Acids; D006728:Hormones; D007328:Insulin; D019308:Palmitic Acid; D005947:Glucose; D009638:Norepinephrine; D004837:Epinephrine