Physical Activity Levels Of Adolescents Research Articles

Association between sedentary recreational time and cardiac autonomic modulation in adolescent boys: cross-sectional study

Sedentary behavior has been shown to be an independent risk factor for high blood pressure, obesity, and low physical activity levels in adolescents. However, the association between sedentary recreational behaviors, such as TV viewing and using computer/video games, and cardiac autonomic modulation in adolescents is not well established. Therefore, the aim of this study was to investigate the association between the time spent on sedentary recreational activities and cardiac autonomic modulation in adolescents. This cross-sectional study included 1149 adolescent boys (aged 16.6 ± 1.2 years). Using a questionnaire, we evaluated their sedentary recreational activities and based on the time spent on these activities, the subjects were classified as high (> 2 h/day) or low (≤ 2 h/day) time spent in a sitting position. Heart rate variability (HRV) was used to assess cardiac autonomic modulation. Time (standard-deviation of all RR intervals [SDNN], root mean square of the squared differences between adjacent normal RR intervals [RMSSD], and the percentage of adjacent intervals over 50 ms [PNN50]), as well as the frequency domains (low [LF] and high [HF] frequency) of HRV were obtained. Longer time spent on sedentary recreational activities was found to be significantly associated with low RMSSD (OR = 1.42, 95% CI 1.11; 1.81) and PNN50 (OR = 1.47, 95% CI 1.15; 1.88). associations were maintained even after adjustments for time of day, abdominal obesity, high blood pressure, and physical activity levels. The time spent on sedentary recreational activities was not associated with SDNN (OR = 1.08, 95% CI 0.84; 1.38), HF (OR = 1.31, 95% CI 0.88; 1.94), LF (OR = 1.19, CI 0.94; 1.52), or LF/HF (OR = 1.19, 95% = 0.93; 1.51) (p > 0.05 for all). In conclusion, longer time spent on sedentary recreational activities is associated with poor cardiac autonomic modulation.

Adolescent Physical Activity Disparities by Parent Nativity Status: the Role of Social Support, Family Structure, and Economic Hardship

In this cross-sectional study, we examine disparities in physical activity (PA) rates, a determinant of obesity risk, by exploring the impact of household economic hardship, social support, and family structure on adolescent physical activity levels. We assess whether these factors have a different impact on PA stratified by parental nativity status (Hispanic adolescents of foreign- and native-born caregivers compared with whites). The sample included 1927 white and Hispanic 15-year-olds of foreign-born (outside of USA) and native US-born caregivers from the Fragile Families and Child Wellbeing Study. We assessed whether economic hardship, family/friend encouragement for PA, married/cohabiting caregivers, and having a resident grandparent was associated with frequency of PA in the past week, while controlling for age, education, and child's sex. We examined the interaction effects of parent nativity on economic hardship and family support. Results indicate disproportionately higher PA levels for white adolescents compared with Hispanic adolescents of foreign-born caregivers (B = -0.41, SE = 0.19, p = 0.03), for adolescents with more family/friend encouragement (B = 0.81, SE = 0.10, p < 0.001), and for adolescents in cohabiting households (B = 0.28, SE = 0.14, p = 0.04); support and hardship factors did not vary by nativity status. Researchers and practitioners should address differences among ethnic/generational subgroups and family/friend supports that may improve adolescent PA levels, particularly among Hispanic adolescent subgroups. Physical activity levels continue to be dismal especially for racial/ethnic minority groups, which puts them at further risk of consequences of physical inactivity, including life-long complications associated with being an obese adolescent.

Is the association between sociodemographic variables and physical activity levels in adolescents mediated by social support and self‐efficacy?

ObjectiveAnalyze whether the association between sociodemographic variables and physical activity levels is mediated by psychosocial factors. MethodsThis is a cross‐sectional epidemiological study of public and private high school students in João Pessoa, Paraíba state, Brazil. A total of 2540 adolescents (57.0% female) were analyzed (16.4±1.2 years). Physical activity was estimated using a questionnaire, self‐efficacy, and parents’ and friends’ social support by scales, all previously validated. ResultsThe association between sex and the physical activity level of adolescents was partially mediated by the social support of parents (β=0.79; p<0.001) and friends (β=2.96; p<0.001), and the association between age and physical activity level was partially mediated by parents’ social support (β=0.78; p<0.001). The associations between sex and age and physical activity levels of adolescents were mediated by the social support of parents and friends. ConclusionsDifferences in physical activity levels between adolescent females and males and between younger and older adolescents may be partially explained by differences in social support provided by parents and friends. Implementation strategies to increase the social support of parents and friends may help reduce the differences in physical activity levels between these subgroups of adolescents.

Social Support for Physical Activity for High Schoolers in Rural Southern Appalachia.

Social support for physical activity (PA) has been shown to enhance PA levels in adolescents. Although social support has been examined extensively in the literature, less is known about the role of social support for PA for high school adolescents in rural southern Appalachia. PA is important because adolescent obesity is greater in Appalachia than in the rest of the United States. This was a qualitative secondary analysis of focus groups conducted in 2013-2014 among parents, teachers, and high school students (N = 77) in 6 counties across rural southern Appalachia. Beets' typology of social support was used to categorize themes. Participants discussed instrumental supports, including providing transportation and paying fees, enrolling child in recreation/sports, and providing PA equipment at home. Performing PA with adolescents and modeling, watching/supervising, and prioritizing PA were identified as conditional supports. Several motivational supports were identified: encouragement, force, and the admiration of people who are active. Participants also identified key informational supports, including discussing the importance/health benefits of PA, how to be physically active, and general advice/information. Barriers to PA engagement (eg, body image issues, bullying, competitive nature of PA opportunities) and the role of referent groups (eg, family, peers, teachers) emerged as important concepts in the discussion. This study identifies opportunities and practical ways for families and schools to provide, build, and strengthen supports for PA among adolescents in rural Appalachia.

Testing the Weiss-Harter-Model: Physical Activity, Self-Esteem, Enjoyment, and Social Support in Children and Adolescents.

BackgroundSeveral theories have been established to explain physical activity (PA) participation. However, many of these theories might not be applicable to adolescent PA behavior as they require a high level of cognitive reflection. Weiss suggests a model for youth which is based on the theoretical concept of Harter, focusing on self-esteem within social, emotional, and developmental aspects to explain behavior. The aim of this study was to test the original and a social support focused alternative version of the Weiss-Harter-model, and to cross-validate the findings in two separate studies.MethodsData from two cross-sectional studies was retrieved and the models tested using structural equation modeling. Participants aged 11–17 years were recruited from a school (Study 1: N = 182) and from the German MoMo study (Study 2: N = 2,274). They filled in questionnaires about perceived competence, social support, self-esteem, PA enjoyment, and minutes of moderate-vigorous PA (MVPA).ResultsNone of the studies showed a good model fit for the original model [Study 1: CFI = 0.870, RMSEA 0.118 (90% CI 0.081–0.158), χ2 = 38.7, p < 0.01; Study 2: CFI = 0.871, RMSEA 0.148 (90% CI 0.140–0.155), χ2 = 1112.6, p < 0.01], explaining only 12% and 17% of MVPA variance, respectively. The alternative model which added the direct paths of social support to MVPA and PA enjoyment had a very good model fit for both Study 1 [CFI = 1.000, RMSEA 0.000 (90% CI 0.000–0.031), χ2 = 4.8, p > 0.05] and Study 2 [CFI = 0.990, RMSEA 0.043 (90% CI 0.035–0.051), χ2 = 103.7, p < 0.01]. The addition of these paths led to changes in effect size and directions of other path coefficients, with self-esteem having a small to meaningless impact on MVPA. The revised models accounted for 38% and 42% explained variance in MVPA, respectively.DiscussionThe prominent role of self-esteem in the original model could not be confirmed. Instead, the results emphasize the role of social support for PA and PA enjoyment, which is in line with current research. Interventions to increase adolescent PA levels should thus focus more on components of social support instead of self-esteem. Future studies are needed to examine the interplay between social support, PA enjoyment and perceived competence as PA determinants.

Sexual Maturation, social support and physical activity in adolescents

To analyze the moderating effect of maturation on the association between social support, received from parents and friends, on physical activity level in adolescents. Cross-sectional study conducted in 2014 with a representative sample of 855 adolescents (54% girls) enrolled in public school of São José dos Pinhais, Brazil. Adolescents reported weekly attendance who received different types of social support for physical activity, which was classified into three categories (“never," "sometimes," "always"). The social support score from each source was computed and classified in tertiles ("low", "intermediate", "high"). The moderate to vigorous leisure time physical activity was evaluated with a valid questionnaire and the score was classified as ≥300 min/wk. The maturation was self-assessed by pubic hairiness by photos and classified as "pubescent" and "post-pubescent". The associations were tested with Poisson regression in STATA 14. The fact that parents "sometimes" (PR: 2.51; 95% CI: 1.42-4.44) or "always" (PR: 4.60; 95% CI: 2.10-10.10) to attend the activities was positively associated with the physical activity of pubertal adolescents. While positive reinforcement for the activities ("always" commenting) was positively associated with the outcome in post-pubertal adolescents (PR: 2.60; 95% CI: 1.01-6.71). The fact that friends "always" watch activities (PR: 2.39; 95% CI: 1.01-5.76), the score "intermediate" (PR: 2.13; 95% CI: 1.28-3.58) and "high" (RP: 1.91; 95% CI: 1.11-3.28) were positively associated with the physical activity of pubertal adolescents. Maturation shows a moderating effect in the association between the social support and physical activity.

Estimated Physical Activity in Adolescents by Wrist-Worn GENEActiv Accelerometers.

Reports of physical activity (PA) measured via wrist-worn accelerometers in adolescents are limited. This study describes PA levels in adolescents at baseline of an obesity prevention and weight management trial. Adolescents (n = 930) at 8 high schools wore an accelerometer for 7 days, with average acceleration values of <50mg, >150mg, and >500mg categorized as sedentary, moderate, and vigorous PA, respectively. In a 3-level mixed-effects generalized linear model, PA was regressed on sex, weight status, and day of week. Daily PA was nested within students, and students within schools, with random effects included for both. Adolescents accumulated a median of 40 minutes daily of moderate to vigorous PA (MVPA). MVPA was significantly different for teens with obesity versus teens with normal weight (-5.4min/d, P = .03); boys versus girls (16.3min/d, P < .001); and Sundays versus midweek (-16.6min/d, P < .001). Average sedentary time increased on weekends (Saturday: 19.1min/d, P < .001; Sunday: 44.8min, P < .001) relative to midweek but did not differ by sex or weight status. Interventions to increase PA in adolescents may benefit from focusing on increasing weekend PA and increasing MVPA in girls.

Identifying Predictors of Changes in Physical Activity Level in Adolescence: A Prospective Analysis in Bosnia and Herzegovina.

It is known that physical activity levels (PA levels) decline during adolescence, but there is a lack of knowledge on possible predictors of changes in PA levels in this period of life. This study aimed to prospectively investigate the relationship between sociodemographic and behavioral factors (predictors), PA levels and changes in PA levels in older adolescents from Bosnia and Herzegovina. The sample comprised 872 participants (404 females) tested at baseline (16 years of age) and at follow-up (18 years of age). Predictors were sociodemographic characteristics (age, gender, socioeconomic status, urban/rural residence, paternal and maternal education level) and variables of substance misuse (consumption of cigarettes, alcohol and illicit drugs). The PA level, as measured by the Physical Activity Questionnaire for Adolescents (PAQ-A), was observed as a criterion. Boys had higher PAQ-A scores than girls at baseline and follow-up. Paternal education levels were correlated with PAQ-A scores at baseline (Spearman’s R: 0.18, 0.15 and 0.14, p < 0.05, for the total sample, females and males, respectively) and at follow-up (Spearman’s R: 0.12, p < 0.01 for the total sample). Logistic regression, which was used to calculate changes in PA levels between baseline and follow-up as a binomial criterion (PA decline vs. PA incline), evidenced a higher likelihood of PA incline in adolescents whose mothers were more educated (OR: 1.29, 95% CI: 1.05–1.60) and who live in urban communities (OR: 1.56, 95% CI: 1.16–2.10). The consumption of illicit drugs at baseline was evidenced as a factor contributing to the lower likelihood of PA incline (OR: 0.36, 95% CI: 0.14–0.92). The negative relationship between illicit drug consumption and PA decline could be a result of a large number of children who quit competitive sports in this period of life. In achieving appropriate PA-levels, special attention should be placed on children whose mothers are not highly educated, who live in rural communities, and who report the consumption of illicit drugs. The results highlighted the importance of studying correlates of PA levels and changes in PA levels during adolescence.

Depressive symptoms, sleep patterns, and physical activity in adolescents with narcolepsy.

To evaluate the association between depressive symptoms, sleep patterns (duration and quality), excessive daytime sleepiness (EDS), and physical activity (PA) in adolescents with narcolepsy. This cross-sectional study included adolescents (ages 10-18 years) with narcolepsy attending a tertiary care facility (The Hospital for Sick Children, Toronto, Canada). Adolescents with narcolepsy completed questionnaires evaluating depressive symptoms (Children's Depression Inventory-2nd edition [CDI-2]), sleep quality (Pittsburgh Sleep Quality Index), EDS (Epworth Sleepiness Scale), and PA (Godin Leisure-Time Exercise Questionnaire). Wrist-based actigraphy was worn by adolescents for 1 week to measure total sleep time (over 24 hr) and sleep efficiency percentage. Thirty adolescents with narcolepsy (mean age = 13.8 ± 2.2 years, 76.7% male) participated. In this cohort of adolescents with narcolepsy, 23.3% had CDI-2 total scores in the elevated range. Greater CDI-2 total scores were associated with poor sleep quality (ρ = 0.571; p = 0.02), EDS (ρ = 0.360; p = 0.05), and lower self-reported PA levels (ρ = -0.512; p < 0.01). Adolescents with narcolepsy report experiencing depressive symptoms, which are associated with poor sleep quality, EDS, and low PA levels. Strategies to improve nocturnal sleep quality and symptoms of EDS as well as promoting increased PA levels in adolescents with narcolepsy may provide an opportunity to improve depressive symptoms in this population. Multidisciplinary care with mental health and sleep specialists for adolescents with narcolepsy is needed.

Health wearables in adolescents: implications for body satisfaction, motivation and physical activity

ABSTRACT Significant proportions of adolescents do not meet recommended physical activity levels. Finding new ways to motivate adolescents to be active is important for physical and psychological well-being. Health and fitness wearables such as the Fitbit have the potential to motivate young people to be active. The aim of this study is to explore if wearing a Fitbit for 5 weeks impacted adolescents’ (14–15 year olds) body satisfaction, physical activity motivation and objective physical activity. The study was conducted with 62 (38 boys, 24 girls) pupils aged 14–15, from five high school physical education classes, in one high school in the United Kingdom. Pupils wore a Fitbit Charge HR for 5 weeks. Pupils wore an accelerometer for 7 days pre and post the 5-week period to explore changes in physical activity levels. Pupils also completed pre-post-test questionnaires to measure body satisfaction and physical activity motivation. Data were analysed using a repeated measures Multivariate Analysis of Variance to explore differences in scores between time and sex. After wearing the Fitbit, the pupils experienced declines in autonomous motivation and increases in both amotivation and controlled motivation, but these differences were not significant. In line with these negative motivational outcomes, pupils engaged in significantly less moderate to vigorous physical activity after wearing the Fitbit. Significant increases in body satisfaction were also experienced by pupils after wearing the Fitbit. These findings suggest that without support Fitbits may make pupils less motivated to be active and decrease the physical activity levels of adolescents.

Rural-Urban Differences in Baseline Dietary Intake and Physical Activity Levels of Adolescents.

IntroductionDifferences in dietary intake and physical activity may explain the higher prevalence of obesity among adolescents living in rural versus urban settings. The objective of this cross-sectional secondary analysis was to compare baseline dietary intake and physical activity of adolescents by rurality.MethodsWe analyzed data on 940 adolescents who participated in ACTION PAC (Adolescents Committed to Improvement of Nutrition and Physical Activity), an obesity prevention and management intervention trial conducted from 2014 through 2017 in 8 public high schools in the southwestern United States. Dietary intake was assessed with the Block Food Screener, and participants completed an exercise log and wore an accelerometer to provide data on physical activity. We compared data by rural–urban commuting area (RUCA) codes and log population density by using multilevel models, with students nested within zip code and repeated measures for accelerometer analysis.ResultsAfter adjusting for socioeconomic status and ethnicity, accelerometer data indicated that moderate-to-vigorous physical activity was 8.17 min/d (P = .02) higher and sedentary time was 20.42 min/d (P = .02) lower in moderately urban areas than in the urban reference area. Each 1-unit increase in log population density was associated with higher reported intake of whole grains (0.02 ounce equivalents, P = .03), potatoes (0.01 cup equivalents, P = .02), and added sugar (0.37 tsp, P = .02) after adjusting for socioeconomic status and ethnicity.ConclusionDifferences in reported dietary intake and physical activity level by measures of rurality were small and inconsistent in direction to explain the disparities observed in rural versus urban areas.

Evaluation of daily physical activity levels with metabolic holter in adolescents

The aim of this study was to evaluate daily physical activity levels in adolescents, aged 11, 12 and 13 with metabolic holter. Totally 99 healthy and volunteer male students, aged 11-13 years, participated in this study. The participants were divided into three groups according to their chronological age: 11 age group (n: 35), 12 age group (n: 34) and 13 age group (n: 30). The physical activity levels of the children's were measured by SenseWear Armband (SWA) for 3 consecutive days (72 hours), in the absence of physical education class days. Height, weight, body mass index, daily total energy consumption, physical activity level, daily average number of steps (STEP), daily average length of stay and daily average sleep time were measured. The data obtained in the study were determined by one way ANOVA and multiple comparison test. P<0.05 was considered significant in all tests. There was a significant difference in the mean values of height (F=20.3; p=0.00), weight (F=12.55; p=0.00), and STEP (F=7.64; p=0.01) in the study group. The difference in height and weight mean was significant in favor of 13 age group (11<12<13, respectively) and STEP was in favor of 11 years (13≤12<11, respectively). The differences between the remaining variables were not significant (p> 0.05). In this study, it was concluded that the adolescents who were in different age groups and did not have physical education classes, the duration of physical activity was low, but their duration of inactivity was high.

Effectiveness of interventions to increase physical activity in individuals with intellectual disabilities: a systematic review of randomised controlled trials.

People with intellectual disabilities (ID) often do not meet recommended guidelines for physical activity. The aim of this study was to systematically review available evidence that evaluated the effectiveness of interventions to increase physical activity in individuals with ID. Five electronic databases (MEDLINE, CINAHL, EMBASE, SPORTDiscus and Cochrane Central Register of Controlled Trials) were searched from inception of the database to July 2017 to identify randomised controlled trials that evaluated the effectiveness of interventions to improve physical activity among people with ID. Trials were included if they measured at least one objective measure of physical activity. Quality appraisal was completed by two independent reviewers using the Cochrane Risk of Bias Tool. The magnitude of treatment effect was estimated for each intervention by calculating the standardised mean difference (SMD) and associated 95% confidence interval. Nine randomised controlled trials (976 participants, 501 women, age range 9months to 83years) were included. Four trials evaluated unimodal interventions and five trials evaluated multimodal health promotion programmes based on using supportive environments to enable sustained behavioural changes in physical activity. None of the trials were rated as low risk of bias as all had at least one item on the Cochrane Risk of Bias Tool that was considered to be high risk. No trials were able to implement participant blinding. Three trials found statistically significant beneficial effects of interventions for increasing physical activity. Results showed that a 10-week progressive resistance training programme led to maintenance of physical activity levels at 24weeks in adolescents with Down syndrome (SMD 0.78, 95% CI 0.17 to 1.40). Additionally, a 12- to 16-month multicomponent diet and physical activity programme produced improvement in physical activity at programme completion in adults with ID (reported effect size of 0.29). Finally, an 8-month physical activity and fitness programme increased physical activity at 8months in adults with ID (SMD 0.91, 95% CI 0.20 to 1.60). Findings regarding other interventions were inconclusive with small effects that were not statistically significant. There is inconsistent evidence of the effects of interventions for improving physical activity levels in individuals with ID. A progressive resistance training programme was found to maintain physical activity levels in adolescents with Down syndrome, while a multicomponent diet and physical activity programme and a physical activity and fitness programme were found to improve physical activity levels in adults with ID. Future trials using rigorous research designs are required to confirm these findings and establish whether other interventions designed to increase physical activity in people with ID are effective.

Entrenamiento mental breve en adolescentes con trastorno alimentario no especificado que presentan hábitos exigentes de actividad física

El objetivo principal del presente estudio fue examinar el efecto de un programa de entrenamiento mental breve sobre el estado afectivo, las actitudes hacia la alimentación y los niveles de actividad física en adolescentes diagnosticadas con Trastorno Alimentario No Especificado que practicaban una rutina exigente de actividad física. Una muestra de ocho mujeres adolescentes chilenas de 15-17 años de edad realizó un programa de entrenamiento mental breve durante ocho semanas una sesión por semana: 1) Conocimiento y establecimiento de objetivos; 2) Focalización y toma de conciencia mental y corporal; 3) Autocontrol psicobiológico; 4) Reposicionamiento del locus de control; 5) Autogestión y control de los pensamientos; 6-7) Re-focalización y reencuadre motivacional, y 8) Generalización y enfoque responsable de la voluntad. El Inventario de Depresión de Beck, el Cuestionario de Actitudes ante la Alimentación EAT–26 y una entrevista breve sobre los niveles de práctica y motivos de actividad física, se aplicaron antes y después del programa. Los resultados reflejan una influencia favorable del programa en la mejora del estado afectivo, de las actitudes hacia la alimentación y hacia la actividad física en las adolescentes intervenidas. Un programa de entrenamiento mental breve sería recomendable como complemento terapéutico en adolescentes con tales características.

A wearable activity tracker intervention for promoting physical activity in adolescents with juvenile idiopathic arthritis: a pilot study

BackgroundChildren and adolescents with juvenile idiopathic arthritis (JIA) are less physically active than their healthy peers and are at high risk of missing out on the general health benefits of physical activity. Wearable activity trackers are a promising option for intervening in this population with potential advantages over traditional exercise prescriptions. The objectives of this study were to: (1) determine the feasibility of a wearable activity tracker intervention in adolescents with JIA; and (2) estimate the variability in response to a wearable activity tracker intervention on the physical activity levels of adolescents with JIA.MethodsParticipants aged 12–18 years with JIA were recruited during their routine rheumatology clinic visits at a tertiary care hospital. Participants completed the 3-Day Physical Activity Recall self-reported questionnaire at baseline, 1 week and 5 week follow-up. At the 1 week follow up, participants were instructed to start wearing an activity tracker for 28 consecutive days. Participants completed a feasibility questionnaire at their end of study visit. Participant demographics, adherence rates and feasibility outcomes were summarized using descriptive statistics. The effect of wearing a tracker on moderate-to-vigorous physical activity (MVPA) and total metabolic equivalents (METs) per day were analyzed using a paired t-test.ResultsTwenty-eight participants (74% female; median age 15.1, range 12.8–18.6) were included in the analysis. All of the participants were able to synchronize the activity tracker to a supported device, use the activity tracker correctly and complete the study measurements. On average, participants had activity logged on their smartphone application for 72% of the intervention period. The standard deviation of the change in mean METs/day was 12.148 and for mean MVPA blocks/day was 3.143 over the study period.ConclusionWrist worn activity tracking is a feasible intervention for adolescent patients with JIA. More research is needed to examine the effect of activity tracking on physical activity levels.Trial RegistrationNot an applicable clinical device trial as per the criteria listed on ClinicalTrials.gov as the primary objective is feasibility.

Split-week Programming for Secondary Physical Education: Inducing Behavioral Change for Lifetime Fitness

There is an imperative need for secondary physical education programming to prepare students for lifetime fitness and health. Physical activity levels in adolescents and adults are dismal, and the negative health outcomes associated with sedentary behaviors are catastrophic. Secondary physical education programs have the opportunity to implement a curriculum that can enable students to create and execute their own health-enhancing fitness plan. The current focus in most programs is on a sport and game model that has had limited results in influencing the adoption of healthy lifestyle habits. The purpose of this article is to provide practitioners with a practical and feasible split-week program model that is designed to potentially induce behavioral change in students for lifelong physical activity and fitness. The split-week program holds health-related fitness education at the core while also teaching outdoor recreation, sport and rhythmic activities.

Is the association between sociodemographic variables and physical activity levels in adolescents mediated by social support and self-efficacy?

ObjectiveAnalyze whether the association between sociodemographic variables and physical activity levels is mediated by psychosocial factors. MethodsThis is a cross-sectional epidemiological study of public and private high school students in João Pessoa, Paraíba state, Brazil. A total of 2540 adolescents (57.0% female) were analyzed (16.4±1.2 years). Physical activity was estimated using a questionnaire, self-efficacy, and parents’ and friends’ social support by scales, all previously validated. ResultsThe association between sex and the physical activity level of adolescents was partially mediated by the social support of parents (β=0.79; p<0.001) and friends (β=2.96; p<0.001), and the association between age and physical activity level was partially mediated by parents’ social support (β=0.78; p<0.001). The associations between sex and age and physical activity levels of adolescents were mediated by the social support of parents and friends. ConclusionsDifferences in physical activity levels between adolescent females and males and between younger and older adolescents may be partially explained by differences in social support provided by parents and friends. Implementation strategies to increase the social support of parents and friends may help reduce the differences in physical activity levels between these subgroups of adolescents.

Longitudinal effects of biopsychosocial variables on physical activity after menarche.

The aim of the current study is to analyze the longitudinal effects of certain biopsychosocial variables (socioeconomic status, Body Mass Index (BMI), body image and well-being (QL)), measured at three different menarche stages (S1: before menarche, S2: soon after menarche, and S3: one year after S2), on physical activity and inactivity levels in early adolescence. The sample comprised 136 Brazilian teenagers (10-13 years old), showing BMI 18.98 kg/m2 at the initial assessment, who voluntarily participated in the study. Data concerning the following variables were collected in 2010 (S1), 2011 (S2) and 2012 (S3): family income (FI) (socioeconomic anamnesis), BMI (body mass and height), well-being (Autoquestionnaire Qualité de Vie Enfant Imagé) and body image (Body Shape Questionnaire). The physical activity and inactivity levels were measured in S3, only, through the International Physical Activity Questionnaire. The Pearson's correlation and the longitudinal path analysis technique were used to statistically analyze the data. The main results indicated that only family income and BMI, measured soon after menarche (S2), showed significant effect on physical activity and inactivity levels. More specifically, family income has positively influenced (β=0.25) physical inactivity levels and negatively influenced (β=-0.14) moderate physical activity levels, whereas BMI has positively influenced (β=0.15) walking levels and negatively influenced (β=-0.13) vigorous physical activity levels. These results suggest that the body image and well-being perceived by the teenagers at different menarche stages are not determining factors of their physical activity levels in early adolescence. On the other hand, the effects of socioeconomic status and BMI on early adolescent girls' physical activity and inactivity levels depend on the assessment period.

청소년의 신체활동 잠재 프로파일 분류에 따른 주변인과의 관계성향

The purpose of this study was to classify the subgroups of physical activity level of adolescents and to examine differences in teacher relations, peer relationships, and family relations according to the classified groups. For this, 660 adolescents were asked to respond to each scale, and the research problem was verified by analyzing latent profiles and one-way ANOVA using the Mplus 7.11 and SPSS 24.0 programs. As a result, the physical activity level was classified into four types of latent groups. In the form of the latent profile, the physical activity level was classified into the group 1 having the lowest physical activity level to the group 4 having the highest physical activity level. As a result of analyzing the mean difference of teacher relations, friendship relations, and family relations according to the latent profile of the classified physical activity level, the average of the group having the highest physical activity level was highest in all of the teacher relations, friendship and family relations. Based on these results, this study discussed the implications of differences in the relative tendency with the surrounding people according to the classification of the latent profile of physical activity level of adolescents in education and policy situation, and suggestions for follow-up study were also presented.

Relationship between musculoskeletal disorders and physical inactivity in adolescents

To determine the correlation between musculoskeletal system disorders and the physical activity levels of adolescents. A total of 417 high school students were included in this cross-sectional study. To explain the musculoskeletal pain and physical activity, a self-administered questionnaire which included the Nordic International Physical Activity Questionnaire Short Form (IPAQ-SF) was distributed. The standardised Nordic musculoskeletal questionnaire showed that 57.3% of the students reported having musculoskeletal disorders in one or more body parts, and 52.2% of them consisted of girls. The mean weekly energy consumption as linked to the physical activity of the participants was found to be 2534.58 (± 2371.31) metabolic equivalent task (MET/wk): 45.8% of the individuals exhibited low levels of activity. A statistically significant relationship was found between experiencing upper/low back pain and the participants’ low physical activity levels. The current study has shown that the prevalence of MSDs was high among high school students, with a correlation being found between low physical activity and back pain. Physical activity levels should hence be considered when evaluating adolescents with musculoskeletal disorders.