Secondary consequences of juvenile idiopathic arthritis in children and adolescents with knee involvement: physical activity, adiposity, fitness, and functional performance.

OBJECTIVE: Secondary consequences of juvenile idiopathic arthritis (JIA) may impact long-term health outcomes. This study examined differences in physical activity, cardiorespiratory fitness, adiposity, and functional performance in children and adolescents with JIA compared to their typically developing (TD) peers. METHODS: Participants with JIA (n = 32; 10-20 years old) and their TD peers (n = 35) volunteered for assessments of: daily moderate-to-vigorous physical activity (MVPA, body-worn accelerometer); peak oxygen consumption (VO2 Peak, incremental bike test); fat mass index (FMI, dual-energy X-ray absorptiometry); and triple-single-leg-hop (TSLH) distance. Statistical analyses were performed in R using four linear mixed-effect models with Bonferroni adjustment (⍺ = 0.0125). Fixed effects were group, sex, and age. Participant clusters based on sex and age (within 1.5 years) were considered as random effects. RESULTS: Participants with JIA displayed lower mean daily MVPA than their TD peers [p = 0.006; ß (98.75% CI); -21.2 (-40.4 to -2.9) min]. VO2 Peak [p = 0.019; -1.4 (-2.5 to -0.2) ml/kg/min] decreased with age. Females tended to have lower VO2 Peak [p = 0.045; -6.4 (-13.0 to 0.4) ml/kg/min] and greater adiposity [p = 0.071; 1.4 (-0.1 to 3.0) kg/m2] than males. CONCLUSION: The findings support the need for strategies to promote MVPA participation in children and adolescents with JIA. Sex and age should be considered in research on the consequences of JIA.

The Effect of Injury Definition and Surveillance Methodology on Measures of Injury Occurrence and Burden in Elite Volleyball.

A time-loss injury definition continues to be the most widely used injury definition despite evidence that it fails to accurately capture overuse injuries. An overuse injury questionnaire, using an "all complaints" definition has been created to address the limitation of a time-loss definition. The main aim of this work was to determine the effect that injury definition and registration methodology has on the collection of knee injuries among elite level volleyball players. To reach this goal, seventy-two volleyball players were prospectively followed over 32-weeks. Time-loss injuries were captured using an individual injury report form (IIRF). Study participants completed an overuse injury questionnaire (mOIQ) via a weekly short message service (SMS). The IIRF captured 15 time-loss knee injuries in 72 study participants (20%). Based on the mOIQ, 84.7% of participants reported having a knee problem and 66.7% sustained a substantial knee problem. All IIRF knee injuries captured were also registered by the mOIQ. Agreement on the specific diagnosis occurred for 66.7% of injuries resulting in a moderate Kappa score of 0.51. In conclusion, an overuse injury questionnaire provided a greater understanding of the magnitude and burden of knee injuries in this population.