title: Muscle Metabolic Responses During Dynamic In-Magnet Exercise Testing: A Pilot Study in Children with an Idiopathic Inflammatory Myopathy.
abstract: OBJECTIVE
  The clinical utility of supine in-magnet bicycling in combination with phosphorus magnetic resonance spectroscopy ((31)P MRS) to evaluate quadriceps muscle metabolism was examined in four children with juvenile dermatomyositis (JDM) in remission and healthy age- and gender-matched controls.
  
  
  METHODS
  Two identical maximal supine bicycling tests were performed using a magnetic resonance-compatible ergometer. During the first test, cardiopulmonary performance was established in the exercise laboratory. During the second test, quadriceps energy balance and acid/base balance during incremental exercise and phosphocreatine recovery were determined using (31)P MRS.
  
  
  RESULTS
  During the first test, no significant differences were found between patients with JDM and their healthy peers regarding cardiopulmonary performance. The outcomes of the first test indicate that both groups attained maximal performance. During the second test, quadriceps phosphocreatine and pH time courses were similar in all but one patient experiencing idiopathic postexercise pain. This patient demonstrated faster phosphocreatine depletion and acidification during exercise, yet postexercise mitochondrial adenosine triphosphate synthesis rate measured by phosphocreatine recovery kinetics was approximately twofold faster than control (time constant 23 seconds vs 43 ± 7 seconds, respectively).
  
  
  CONCLUSIONS
  These results highlight the utility of in-magnet cycle ergometry in combination with (31)P MRS to assess and monitor muscle energetic patterns in pediatric patients with inflammatory myopathies.
authors.affiliation: Division of Pediatrics, Child Development and Exercise Center, Wilhelmina Children's Hospital, University Medical Center Utrecht, Rm KB.02.056.0, P.O. Box 85090, NL-3508 AB Utrecht, The Netherlands. Electronic address: m.vanbrussel@umcutrecht.nl.
authors.forename: Marco
authors.initials: M
authors.lastname: van Brussel
authors.affiliation: Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
authors.forename: Joep W M
authors.initials: JW
authors.lastname: van Oorschot
authors.affiliation: Biomodeling and Bioinformatics, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
authors.forename: Joep P J
authors.initials: JP
authors.lastname: Schmitz
authors.affiliation: Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
authors.forename: Klaas
authors.initials: K
authors.lastname: Nicolay
authors.affiliation: Department of Pediatric Rheumatology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Annet
authors.initials: A
authors.lastname: van Royen-Kerkhof
authors.affiliation: Division of Pediatrics, Child Development and Exercise Center, Wilhelmina Children's Hospital, University Medical Center Utrecht, Rm KB.02.056.0, P.O. Box 85090, NL-3508 AB Utrecht, The Netherlands.
authors.forename: Tim
authors.initials: T
authors.lastname: Takken
authors.affiliation: Division of Pediatrics, Child Development and Exercise Center, Wilhelmina Children's Hospital, University Medical Center Utrecht, Rm KB.02.056.0, P.O. Box 85090, NL-3508 AB Utrecht, The Netherlands; Neuroimaging Center, Department of Neuroscience, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Jeroen A L
authors.initials: JA
authors.lastname: Jeneson
mesh_terms: D000255:Adenosine Triphosphate / Q000096:biosynthesis; D000293:Adolescent; D003872:Dermatitis / Q000378:metabolism*; D004734:Energy Metabolism; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008931:Mitochondria, Muscle / Q000378:metabolism; D009220:Myositis / Q000378:metabolism*; D010725:Phosphocreatine / Q000378:metabolism; D010865:Pilot Projects; D052097:Quadriceps Muscle / Q000378:metabolism*
chemical_list: D010725:Phosphocreatine; D000255:Adenosine Triphosphate
keywords: (31)P MRS; Human; bicycle ergometry; dermatomyositis; exercise