title: Exercise oxidative skeletal muscle metabolism in adolescents with cystic fibrosis.
abstract: What is the central question of this study? Do intrinsic abnormalities in oxygenation and/or muscle oxidative metabolism contribute to exercise intolerance in adolescents with mild cystic fibrosis? What is the main finding and its importance? This study found no evidence that in adolescents with mild cystic fibrosis in a stable clinical state intrinsic abnormalities in skeletal muscle oxidative metabolism seem to play a clinical significant role. Based on these results, we concluded that there is no metabolic constraint to benefit from exercise training. Patients with cystic fibrosis (CF) are reported to have limited exercise capacity. There is no consensus about a possible abnormality in skeletal muscle oxidative metabolism in CF. Our aim was to test the hypothesis that abnormalities in oxygenation and/or muscle oxidative metabolism contribute to exercise intolerance in adolescents with mild CF. Ten adolescents with CF (12-18 years of age; forced expiratory volume in 1 s >80% of predicted; and resting oxygen saturation >94%) and 10 healthy age-matched control (HC) subjects were tested with supine cycle ergometry using near-infrared spectroscopy and (31)P magnetic resonance spectroscopy to study skeletal muscle oxygenation and oxidative metabolism during rest, exercise and recovery. No statistically significant (P > 0.1) differences in peak workload and peak oxygen uptake per kilogram lean body mass were found between CF and HC subjects. No differences were found between CF and HC subjects in bulk changes of quadriceps phosphocreatine (P = 0.550) and inorganic phosphate (P = 0.896) content and pH (P = 0.512) during symptom-limited exercise. Furthermore, we found statistically identical kinetics for phosphocreatine resynthesis during recovery for CF and HC subjects (P = 0.53). No statistically significant difference in peak exercise arbitrary units for total haemoglobin content was found between CF and HC subjects (P = 0.66). The results of this study provide evidence that in patients with mild CF and a stable clinical status (without signs of systemic inflammation and/or chronic Pseudomonas aeruginosa colonization), no intrinsic metabolic constraints and/or abnormalities in oxygenation and/or muscle oxidative metabolism contribute to exercise intolerance.
authors.affiliation: Child Development & Exercise Center, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Maarten
authors.initials: M
authors.lastname: Werkman
authors.affiliation: Child Development & Exercise Center, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Jeneson
authors.affiliation: Child Development & Exercise Center, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Paul
authors.initials: P
authors.lastname: Helders
authors.affiliation: Cystic Fibrosis Center and Department of Pediatric Respiratory Medicine, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Bert
authors.initials: B
authors.lastname: Arets
authors.affiliation: Cystic Fibrosis Center and Department of Pediatric Respiratory Medicine, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Kors
authors.initials: K
authors.lastname: van der Ent
authors.affiliation: Department of Radiology, University Medical Center Utrecht, The Netherlands.
authors.forename: Birgitta
authors.initials: B
authors.lastname: Velthuis
authors.affiliation: Department of Radiology, University Medical Center Utrecht, The Netherlands.
authors.forename: Rutger
authors.initials: R
authors.lastname: Nievelstein
authors.affiliation: Child Development & Exercise Center, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands.|Partner of Shared Utrecht Pediatric Exercise Research (SUPER) Laboratory, Utrecht, The Netherlands.
authors.forename: Tim
authors.initials: T
authors.lastname: Takken
authors.affiliation: Child Development & Exercise Center, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Erik
authors.initials: E
authors.lastname: Hulzebos
mesh_terms: D000293:Adolescent; D001823:Body Composition / Q000502:physiology; D015992:Body Mass Index; D003550:Cystic Fibrosis / Q000378:metabolism* / Q000503:physiopathology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D010725:Phosphocreatine / Q000378:metabolism; D012146:Rest / Q000502:physiology
chemical_list: D006454:Hemoglobins; D010725:Phosphocreatine; D010100:Oxygen