[Prevalence of excessive screen time and associated factors in adolescents]. / Prevalência de tempo excessivo de tela e fatores associados em adolescentes.

OBJECTIVE: To determine the prevalence of excessive screen time and to analyze associated factors among adolescents. METHODS: This was a cross-sectional school-based epidemiological study with 2,874 high school adolescents with age 14-19 years (57.8% female) from public and private schools in the city of João Pessoa, PB, Northeast Brazil. Excessive screen time was defined as watching television and playing video games or using the computer for more than two hours per day. The associated factors analyzed were: sociodemographic (gender, age, economic class, and skin color), physical activity and nutritional status of adolescents. RESULTS: The prevalence of excessive screen time was 79.5% (95%CI: 78.1-81.1) and it was higher in males (84.3%) compared to females (76.1%; p<0,001). In multivariate analysis, adolescent males, aged 14-15 years old, of higher economic classes had higher chances of exposure to excessive screen time. The level of physical activity and nutritional status of adolescents were not associated with excessive screen time. CONCLUSIONS: The prevalence of excessive screen time was high and varied according to sociodemographic characteristics of adolescents. It is necessary to develop interventions to reduce the excessive screen time among adolescents, particularly in subgroups with higher exposure.

Validation of psychosocial scales for physical activity in university students.

OBJECTIVE Translate the Patient-centered Assessment and Counseling for Exercise questionnaire, adapt it cross-culturally and identify the psychometric properties of the psychosocial scales for physical activity in young university students. METHODS The Patient-centered Assessment and Counseling for Exercise questionnaire is made up of 39 items divided into constructs based on the social cognitive theory and the transtheoretical model. The analyzed constructs were, as follows: behavior change strategy (15 items), decision-making process (10), self-efficacy (6), support from family (4), and support from friends (4). The validation procedures were conceptual, semantic, operational, and functional equivalences, in addition to the equivalence of the items and of measurements. The conceptual, of items and semantic equivalences were performed by a specialized committee. During measurement equivalence, the instrument was applied to 717 university students. Exploratory factor analysis was used to verify the loading of each item, explained variance and internal consistency of the constructs. Reproducibility was measured by means of intraclass correlation coefficient. RESULTS The two translations were equivalent and back-translation was similar to the original version, with few adaptations. The layout, presentation order of the constructs and items from the original version were kept in the same form as the original instrument. The sample size was adequate and was evaluated by the Kaiser-Meyer-Olkin test, with values between 0.72 and 0.91. The correlation matrix of the items presented r < 0.8 (p < 0.05). The factor loadings of the items from all the constructs were satisfactory (> 0.40), varying between 0.43 and 0.80, which explained between 45.4% and 59.0% of the variance. Internal consistency was satisfactory (α ≥ 0.70), with support from friends being 0.70 and 0.92 for self-efficacy. Most items (74.3%) presented values above 0.70 for the reproducibility test. CONCLUSIONS The validation process steps were considered satisfactory and adequate for applying to the population.

Reliability and validity of a physical activity social support assessment scale in adolescents--ASAFA Scale.

OBJECTIVE: To analyze the reliability and validity of a scale used to measure social support for physical activity in adolescents - ASAFA Scale. METHODS: This study included 2,755 adolescents (57.6% girls, 16.5 ± 1.2 years of age), from Joao Pessoa, Paraiba, Brazil. Initially, the scale was consisted of 12 items (6 for social support from parents and 6 from friends). The reliability of the scale was estimated by Cronbach's alpha coefficient (α), by the Composite Reliability (CR), and by the model with two factors and factorial invariance by Confirmatory Factor Analysis (CFA) adequacy. RESULTS: The CFA results confirmed that the social support scale contained two factors (factor 1: social support from parents; factor 2: social support from friends) with five items each (one item was excluded from each scale), all with high factor loadings (> 0.65) and acceptable adjustment indexes (RMR = 0.050; RMSEA = 0.063; 90%CI: 0.060 - 0.067); AGFI = 0.903; GFI = 0.940; CFI = 0.934, NNFI = 0.932). The internal consistency was satisfactory (parents: α ≥ 0.77 and CR ≥ 0.83; friends: α ≥ 0.87 and CR ≥ 0.91). The scale's factorial invariance was confirmed (p > 0.05; Δχ2 and ΔCFI ≤ 0.01) across all subgroups analyzed (gender, age, economic class). The construct validity was evidenced by the significant association (p < 0.05) between the adolescents physical activity level and the social support score of parents (rho = 0.29) and friends (rho = 0.39). CONCLUSIONS: The scale showed reliability, factorial invariance and satisfactory validity, so it can be used in studies with adolescents.

Perceived environmental characteristics and psychosocial factors associated with physical activity levels in adolescents from Northeast Brazil: structural equation modelling analysis.

This study aimed to investigate the direct and indirect associations between perceived environmental characteristics and psychosocial factors and physical activity levels in adolescents from Northeast Brazil. The sample was composed of 2,361 adolescents aged 14-19 years (56.6% female). Physical activity was measured using a questionnaire and environmental (perceived environmental characteristics) and psychosocial (self-efficacy, social support from parents and friends for physical activity) factors with previously validated scales. Perceived environmental characteristics were not directly associated with the levels of physical activity, but exhibited significant indirect associations, mediated by self-efficacy in males. Self-efficacy and social support were positively and directly associated with physical activity levels, and part of the associations between social support and physical activity was mediated by self-efficacy. Perception of self-efficacy and social support, important factors associated with physical activity levels in adolescents, should be the target of interventions aimed at increasing physical activity. Favorable environments for physical activity also need to be considered, since they have a positive influence on the self-efficacy of adolescents.

[Prevalence of physical inactivity and associated factors among adolescents commuting to school]. / Prevalência e fatores associados à inatividade física nos deslocamentos para escola em adolescentes.

The aim of this study was to verify the prevalence of physical inactivity and associated factors among adolescents commuting to school. This was an epidemiological study based on secondary data from a sample of 4,207 adolescents (14-19 years). Data were collected through a previously validated questionnaire (GSHS-WHO). Adolescents were classified as "inactive in commuting" when they reported not commuting to school actively (e.g., walking or bicycling) and/or spent less than 20 minutes getting to and from school. 43% (95%CI: 41.5-44.5) of adolescents were physically inactive in commuting. Place of residence and maternal schooling were statistically associated with outcome (inactivity in commuting to school) (p<0.01). Among male adolescents, physical inactivity in commuting was significantly associated with age (p=0.02) and skin color (p=0.04). Inactivity in commuting was relatively common when compared to other studies.