@article{RufBeerKoestleretal.2019,
  author    = {Ruf, Katharina and Beer, Meinrad and K{\"o}stler, Herbert and Weng, Andreas Max and Neubauer, Henning and Klein, Alexander and Platek, Kathleen and Roth, Kristina and Beneke, Ralph and Hebestreit, Helge},
  title     = {Size-adjusted muscle power and muscle metabolism in patients with cystic fibrosis are equal to healthy controls - a case control study},
  series = {BMC Pulmonary Medicine},
  volume    = {19},
  journal   = {BMC Pulmonary Medicine},
  doi       = {10.1186/s12890-019-1039-8},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-200981},
  pages     = {269},
  year      = {2019},
  abstract  = {Background Skeletal muscle function dysfunction has been reported in patients with cystic fibrosis (CF). Studies so far showed inconclusive data whether reduced exercise capacity is related to intrinsic muscle dysfunction in CF. Methods Twenty patients with CF and 23 age-matched controls completed an incremental cardiopulmonary cycling test. Further, a Wingate anaerobic test to assess muscle power was performed. In addition, all participants completed an incremental knee-extension test with 31P magnetic resonance spectroscopy to assess muscle metabolism (inorganic phosphate (Pi) and phosphocreatinine (PCr) as well as intracellular pH). In the MRI, muscle cross-sectional area of the M. quadriceps (qCSA) was also measured. A subgroup of 15 participants (5 CF, 10 control) additionally completed a continuous high-intensity, high-frequency knee-extension exercise task during 31P magnetic resonance spectroscopy to assess muscle metabolism. Results Patients with CF showed a reduced exercise capacity in the incremental cardiopulmonary cycling test (VO2peak: CF 77.8 ± 16.2\%predicted (36.5 ± 7.4 ml/qCSA/min), control 100.6 ± 18.8\%predicted (49.1 ± 11.4 ml/qCSA/min); p < 0.001), and deficits in anaerobic capacity reflected by the Wingate test (peak power: CF 537 ± 180 W, control 727 ± 186 W; mean power: CF 378 ± 127 W, control 486 ± 126 W; power drop CF 12 ± 5 W, control 8 ± 4 W. all: p < 0.001). In the knee-extension task, patients with CF achieved a significantly lower workload (p < 0.05). However, in a linear model analysing maximal work load of the incremental knee-extension task and results of the Wingate test, respectively, only muscle size and height, but not disease status (CF or not) contributed to explaining variance. In line with this finding, no differences were found in muscle metabolism reflected by intracellular pH and the ratio of Pi/PCr at submaximal stages and peak exercise measured through MRI spectroscopy. Conclusions The lower absolute muscle power in patients with CF compared to controls is exclusively explained by the reduced muscle size in this study. No evidence was found for an intrinsic skeletal muscle dysfunction due to primary alterations of muscle metabolism.},
  language  = {en}
}
@article{RufThomasBrunneretal.2019,
  author    = {Ruf, Katharina and Thomas, Wolfgang and Brunner, Maximilian and Speer, Christian P. and Hebestreit, Helge},
  title     = {Diverging effects of premature birth and bronchopulmonary dysplasia on exercise capacity and physical activity - a case control study},
  series = {Respiratory Research},
  volume    = {20},
  journal   = {Respiratory Research},
  doi       = {10.1186/s12931-019-1238-0},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-202449},
  pages     = {260},
  year      = {2019},
  abstract  = {Background Extreme prematurity has been associated with exercise intolerance and reduced physical activity. We hypothesized that children with bronchopulmonary dysplasia (BPD) would be especially affected based on long-term lung function impairments. Therefore, the objective of this study was to compare exercise capacity and habitual physical activity between children born very and extremely preterm with and without BPD and term-born children. Methods Twenty-two school-aged children (aged 8 to 12 years) born with a gestational age < 32 weeks and a birthweight < 1500 g (9 with moderate or severe BPD (=BPD), 13 without BPD (=No-BPD)) and 15 healthy term-born children (=CONTROL) were included in the study. Physical activity was measured by accelerometry, lung function by spirometry and exercise capacity by an incremental cardiopulmonary exercise test. Results Peak oxygen uptake was reduced in the BPD-group (83 ± 11\%predicted) compared to the No-BPD group (91 ± 8\%predicted) and the CONTROL group (94 ± 9\%predicted). In a general linear model, variance of peak oxygen uptake was significantly explained by BPD status and height but not by prematurity (p < 0.001). Compared to CONTROL, all children born preterm spent significantly more time in sedentary behaviour (BPD 478 ± 50 min, No-BPD 450 ± 52 min, CONTROL 398 ± 56 min, p < 0.05) and less time in moderate-to-vigorous-physical activity (BPD 13 ± 8 min, No-BPD 16 ± 8 min, CONTROL 33 ± 16 min, p < 0.001). Prematurity but not BPD contributed significantly to explained variance in a general linear model of sedentary behaviour and likewise moderate-to-vigorous-physical activity (p < 0.05 and p < 0.001 respectively). Conclusion In our cohort, BPD but not prematurity was associated with a reduced exercise capacity at school-age. However, prematurity regardless of BPD was related to less engagement in physical activity and more time spent in sedentary behaviour. Thus, our findings suggest diverging effects of prematurity and BPD on exercise capacity and physical activity."},
  language  = {en}
}
@article{NentwichRufGirschicketal.2019,
  author    = {Nentwich, Julia and Ruf, Katharina and Girschick, Hermann and Holl-Wieden, Annette and Morbach, Henner and Hebestreit, Helge and Hofmann, Christine},
  title     = {Physical activity and health-related quality of life in chronic non-bacterial osteomyelitis},
  series = {Pediatric Rheumatology},
  volume    = {17},
  journal   = {Pediatric Rheumatology},
  doi       = {10.1186/s12969-019-0351-4},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-323710},
  year      = {2019},
  abstract  = {Background Chronic non-bacterial osteomyelitis (CNO) is an autoinflammatory disorder of the skeletal system of yet unknown etiology. Patients present with local bone pain and inflammation and - to our experience - often suffer from functional impairment with significant disabilities of daily life. The objective of this study was to assess physical activity, fitness and health-related quality of life (HRQOL) in adolescents with established diagnosis of CNO versus healthy controls (HC). Methods 15 patients with CNO and 15 age and gender matched HC aged 13-18 years, completed questionnaires, performed an incremental exercise test with gas exchange measures up to voluntary fatigue and wore an accelerometer over 7 days at home to assess physical activity behavior. Results At the time of assessment, 5 CNO patients were in clinical, one in radiological and 5 in clinical and radiological remission. 7 did not receive any therapy at the time of assessment. The results of the exercise test and of the accelerometry did not show any significant difference between CNO and HC. However, reported sports participation was lower in patients with CNO and PedsQL3.0 and 4.0 showed significant lower values in most of the scores indicating reduced HRQOL. Conclusion Although most CNO patients showed a favorable course of disease without any relevant differences in objective measurements of physical activity and fitness versus HC at the time of assessment, questionnaires revealed perceived limitations. Further studies are needed to measure HRQOL and to validate questionnaires in patients with CNO against objective measures including more participants with a higher level of disease activity.},
  language  = {en}
}