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Objectives: To develop a questionnaire able to assess time spent by youth in a wide range of leisure-time sedentary behaviors (SB) and evaluate its test-retest reliability and criterion validity.Design: Cross-sectional observational.Methods: The reliability sample included 194 youth, aged 10-18 years, who completed the questionnaire twice, separated by one-week interval. The validity study comprised 1207 participants aged 8-18 years. Participants wore an accelerometer for 7 consecutive days. The questionnaire was designed to assess the amount of time spent in twelve different SB during weekdays and weekends, separately. In order to avoid usual phenomenon of time over reporting, values were adjusted to real available leisure-time (LT) for each participant. Reliability was assessed by using Intraclass Correlation Coefficients (ICC) and weighted (quadratic) kappa (k), and validity was assessed by using Pearson correlation and Bland-Altman plots.Results: The reliability of questionnaire showed a moderate-to-substantial agreement for the most (91%) of items (k=0.43-0.74; ICC=0.41-0.79) with three items (4%) reaching an almost perfect agreement (ICC=0.82-0.83). Only 'sitting and talking' evidenced fair-to-moderate reliability (k=0.27-0.39; ICC=0.34-0.46). The relationship between average sedentary time assessed by the questionnaire and accelerometry was moderate (r=0.36; p<0.001). Systematic biases were not found between questionnaire and accelerometer sedentary time for average day (r=0.05; p=0.11) but Bland-Altman plots suggest moderate discrepancies between both methods of SB measurement (mean=19.86; limits of agreement=-280.04 to 319.76).Conclusions: The questionnaire showed moderate to good test-retest reliability and a moderate level of validity for assessing SB in youth, similar or slightly better to previously published in this population. [ABSTRACT FROM AUTHOR]

The aim of the present study was to examine the associations of objectively measured physical activity (PA) with several markers of fatness and fitness in a relatively large sample of adolescents with Down syndrome (DS). This study comprised a total of 100 adolescents with DS (37 females) aged 11-20 years-old, and a sex-matched sample of 100 adolescents without disabilities, participating in the UP&DOWN study. The ALPHA health-related fitness test battery for adolescents was used to assess fatness and fitness. PA was measured by accelerometry. Adolescents with DS had higher fatness and significantly lower fitness levels in all variables measured than adolescents without DS (all p<0.05). Moderate-to-large effects were observed in fatness variables (d=0.65-1.42), but particularly large values were found in fitness variables (d=2.05-2.43). In addition, PA levels was not associated with fatness variables, whereas total PA and vigorous PA were associated with all fitness variables (p<0.05), and moderate-vigorous PA (MVPA) was associated with muscular fitness (p<0.05), after adjusting for potential confounders. Further analysis revealed that there were differences in fitness by tertiles of vigorous PA between the lowest and the highest groups in all fitness variables (all p<0.05). However, no significant differences were found in fitness by tertiles of MVPA according with PA guidelines (≥60min in MVPA). Our findings indicate that PA levels are not associated with fatness variables, whereas high PA levels, in particular vigorous PA, are positively associated with high fitness in adolescents with DS. [ABSTRACT FROM AUTHOR]

The current study aimed at analyzing the associations between latent transitions based on sedentary time and physical activity levels and changes in Health-Related Quality of Life (HRQoL), positive affect, and negative affect over two years in children and adolescents. Longitudinal design. Participants were 1099 children and adolescents (544 girls) aged 8–18 years old (11.72 ± 2.39 years). Sedentary and physical activity levels were assessed by accelerometry. Well-being was approached through self-reported HRQoL, positive affect, and negative affect. Latent profile and latent transition analysis were developed at baseline and 2-year follow-up. Furthermore, we analyzed the cross-sectional relationship between lifestyle profiles and well-being, as well as the associations between profiles transitions and changes in well-being indicators. Four profiles were identified at both time-points, respectively: highly sedentary (7.7% and 8.3%), sedentary (34.4% and 35.9%), active (46.3% and 44.3%), and highly active (11.6% and 11.5%). Participants belonging to the highly active profiles showed better HRQL (p < 0.05 at both timepoints) than sedentary participants, and better positive affect (p < 0.05 at follow-up) than those in sedentary and active profiles. Lifestyle profiles were unstable to moderate stable, where sedentary and active profiles were the most stable patter (63.7% and 61.9%, respectively), and highly sedentary and highly active were the least (34.1% and 38.3%, respectively). Changing from an active to a sedentary profile was associated with a significantly greater decrease on the positive affect than keeping on active or changed from a sedentary to an active profile, whereas changing to an active profile attenuated the decrease in HRQoL. This study identified lifestyle profiles transitions among young population, and demonstrates the importance of these behaviors patterns on well-being indicators. These findings suggest the development of practical interventions aimed at promoting healthy lifestyles (i.e., increasing PA and reducing ST) in those youth with sedentary profiles, which will cause an increase on feelings of well-being. • Four profiles were found (highly sedentary, sedentary, active, and highly active). • Active profiles were associated with better HRQoL and positive affect. • Lifestyle profiles were unstable to moderate stable, ranging from 34.1% to 63.7%. • Changing to a sedentary profile caused a greater decrease on positive affect. • Changing to an active profile attenuated the decrease in HRQoL. [ABSTRACT FROM AUTHOR]