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Background: Carbon dioxide (CO2) retention during exercise is uncommon in mild to moderate lung disease in cystic fibrosis (CF). The ability to deal with increased CO2 is dependent on the degree of airflow limitation and inherent CO2 sensitivity. CO2 retention (CO2R) can be defined as a rise in PETCO2 tension of ⩾5 mm Hg with exercise together with a failure to reduce PETCO2 tension after peak work by at least 3 mm Hg by the termination of exercise. Aim: To ascertain if carbon dioxide retention during exercise is associated with more rapid decline in lung function. Methods: Annual spirometric and exercise data from 58 children aged 11-15 years, with moderate CF lung disease between 1996 and 2002 were analysed. Results: The mean FEV1 at baseline for the two groups was similar; the CO2R group (n =15) was 62% and the non-CO2 retention group (CO2NR) was 64% (n = 43). The decline in FEV1 after 12 months was -3.2% (SD 1.1) in the CO2R group and -2.3% (SD 0.9) in the CO2NR group. The decline after 24 months was -6.3% (SD 1.3) and -1.8% (SD 1.1) respectively. After 36 months, the decline in FEV1 was -5.3% (SD 1.2) and -2.6% (SD 1.1) respectively. The overall decline in lung function was 14.8% (SD 2.1) in the CO2R group and 6.7% (SD 1.8) in the CO2NR group. Using the primary outcome measure as a decline in FEV1 of >9%, final multivariate analysis showed that the relative risks for this model were (95% CIs in parentheses): ΔPETCO2 11.61 (3.41 to 24.12), peak VO2 1.23 (1.10 to 1.43), and initial FEV1 1.14(1.02 to 1.28). Conclusion: Results show that the inability to defend carbon dioxide during exercise is associated with a more rapid decline in lung function. [ABSTRACT FROM AUTHOR]

Objective: To determine the reliability of formal exercise testing and the reliability of functional and activity questionnaires in children with juvenile idiopathic arthritis (JIA)., Methods: Children with JIA of any subtype ages 8-16 years who were recruited to a randomized trial comparing different exercise therapies participated in 2 preintervention sessions of exercise testing 2-6 weeks apart. Exercise testing included 1) submaximal oxygen uptake (VO(2submax)), 2) peak VO(2) (VO(2peak)), and 3) anaerobic power using modified Wingate tests (W(ant)). Two physical function questionnaires (the Childhood Health Assessment Questionnaire [C-HAQ] and Revised Activity Scale for Kids [ASK]) and 1 daily physical activity questionnaire (the Habitual Activity Estimation Scale [HAES]) were also completed at these times. Test-retest reliability was assessed using type 3, intrarater intraclass correlation coefficient (ICC(3,1)) and Bland and Altman plots were used to determine limits of agreement., Results: Data were available for 74 patients (58 girls). VO(2submax), VO(2peak), and W(ant) demonstrated high reliability (ICC(3,1) 0.82, 0.91, and 0.94, respectively). C-HAQ and ASK questionnaires also had very high reliability (ICC(3,1) 0.82 and 0.91, respectively). The HAES demonstrated low reliability for total activity score (ICC(3,1) 0.15) and moderate reliability when the number of very active hours was analyzed separately (ICC(3,1) 0.59)., Conclusion: Results of this investigation suggest that exercise testing and functional questionnaires in children with JIA are consistent and reliable. Reliability of the HAES total score was poor, but moderate when the very active hours subscale score was used.

Objective: To examine the effectiveness of high-intensity aerobic training compared with low-intensity training in terms of energy cost of locomotion, peak oxygen uptake, peak power, and self-reported physical function in children with juvenile idiopathic arthritis (JIA)., Methods: Eighty children with JIA, ages 8-16 years, were enrolled in a randomized, single-blind controlled trial. Both groups participated in a 12-week, 3-times-weekly training program consisting of high-intensity aerobics in the experimental group and qigong in the control group. Subjects underwent exercise testing measuring submaximal oxygen uptake at 3 km/hour (VO(2submax)) as the primary outcome, maximal oxygen uptake, and peak power at the beginning and end of the program. Physical function was measured using the Child Health Assessment Questionnaire (C-HAQ)., Results: The exercise program was well tolerated in both groups. There was no difference in VO(2submax) or any other exercise testing measures between the groups through the study period and no indication of improvement. Both groups showed significant improvements in C-HAQ with no difference between the groups. Adherence was higher in the control group than the experimental group., Conclusion: Our findings suggest that activity programs with or without an aerobic training component are safe and may result in an important improvement in physical function. The intensity of aerobic training did not seem to provide any additional benefits, but higher adherence in the qigong program may suggest that less intensive regimens are easier for children with JIA to comply with, and provide a degree of benefit equivalent to more intensive programs.