Short sleep duration in childhood has been associated with an increased risk of overweight and obesity. Research suggests that physical activity might mediate this association; however, studies examining associations between physical activity and sleep in young children have reported equivocal findings. A possible explanation for these inconsistencies is that past studies have looked at total physical activity counts rather than examining physical activity regularity. We aim to explore the relationship of regular physical activity, sedentary behavior, and sleep in preschoolers and kindergartners. 131 children (ages 4-6) were included in this study. Each child wore a waist-worn accelerometer for three days and three nights. Waist-worn accelerometers reliably measure sleep and physical activity in children. Associations of regular physical activity, sedentary behavior, and sufficient sleep were determined using logistic regression models. There was no association between the number of days that children engaged in physical activity (≥ 60 minutes) and sufficient sleep. Further, there was no association between the number of days that children engaged in ≥ 20 minutes of vigorous activity and sufficient sleep. Children who engaged in minimal sedentary activity had greater odds of obtaining sufficient sleep as compared to children who engaged in more sedentary activity.

Introduction: The prevalence of childhood and adolescent obesity in the U.S. and in other countries has continued to rise over the last several decades. Health behaviors such as physical activity and inactivity patterns have been shown to influence rates of obesity among adolescents. Racial/ethnic disparities related to adolescent obesity have been recognized through existing research, and differences in socioeconomic and cultural backgrounds have been noted as possible contributing factors to the risk of adolescents becoming overweight or obese. The primary purpose of this study was to analyze the association of physical activity and sedentary activity with obesity prevalence among adolescents aged 12-15 years old across ethnic groups in the U.S. Methods: This study utilized data from the combined 2007-2012 National Health and Nutrition Examination Survey (NHANES). Descriptive characteristics of the study population were analyzed for both ethnicity and BMI status, and Chi-square tests were used to assess differences among the variables. The association between BMI status categories and ethnicity were evaluated. A univariate analysis was conducted to evaluate the association of the independent and covariate variables with obese status among adolescents. A multivariable logistic regression was also performed to determine the association between BMI status and physical activity, controlling for the covariate variables. For sedentary activity, the frequency statistics were analyzed between each of the ethnicities and BMI status, and t-tests were conducted to determine statistical significance. Results: The sample size for this population included 939 adolescents. Approximately 40% of adolescents were categorized as obese, according to age- and sex-specific BMI percentiles. Among ethnicity, Non-Hispanic white adolescents had the greatest prevalence of obesity, compared to Non-Hispanic Black and Mexican-American adolescents. There was not significant association between BMI status and demographic characteristics, including ethnicity, in the sample. Regarding physical activity, there was some indication that those who engaged in moderate and vigorous physical activity were less likely to be obese, however these findings were not found to be significant. Non-Hispanic black obese adolescents reported significantly less moderate activity compared to Non-Hispanic white adolescents(p=0.02). Obese adolescents in this sample had reported slightly less mean sitting time per day, compared to those who were not obese. Conclusion: Although the findings of this analysis showed some indication of differences in physical activity and sedentary behavior patterns among obese adolescents, the overall findings did not provide a statistically significant association between the variables and ethnicity. Further studies related to this topic could analyze differences in cultural and social norms across ethnicities that could influence physical activity behaviors in adolescents. Also, access to exercise facilities and differences in dietary behaviors among adolescents could be considered.

abstract: Growing concern about obesity prevalence among youth has prompted the examination of socio-environmental influences that shape the development of eating and activity behaviors believed to regulate weight. Given the presumed significance of close friendships during adolescence, the present investigation assessed longitudinal relations between friends' physical activity, sedentary activity, and healthy eating behaviors and explored whether friends' obesity-promoting behaviors are linked to heightened obesity risk among adolescents. This prospective study utilized two Waves of data from 862 reciprocal and 1908 nonreciprocal same-sex friend dyads participating in the National Longitudinal Study of Adolescent Health. To account for nonindependence tied to membership in a particular friendship dyad, multi-level models were estimated for indistinguishable (i.e., reciprocal) and distinguishable (i.e., nonreciprocal) friend pairs using the Actor Partner Interdependence Model. Adolescents' self-reported physical activity and healthy eating were significantly associated with their own and their friends' physical activity and healthy eating one year later; the strength of socialization across friend dyads did not vary with the frequency of interaction between friends or the stability of friendships over time. Limited support was found for a cumulative risk model of obesity-promoting behaviors as a predictor of increased obesity risk; heightened risk for weight gain was found only for adolescents whose reciprocal same-sex friends reported a higher number of obesity-promoting eating and activity behaviors. Overall, study findings highlight the role of close friends for adolescents' obesity risk and obesity-related behaviors. Stronger evidence of socialization resulted for adolescents that perceived their friends to be salient social models, as reflected by their acknowledgement of an existing friendship with such peers (i.e., reciprocal friends and nominators within nonreciprocal friend dyads). / Dissertation/Thesis / Ph.D. Family and Human Development 2011

Introduction: Mood disorders are a serious burden on Canadians. Physical and sedentary activity are easily modifiable risk factors for many diseases. An association with depression could have important implications Objective: To investigate any cross-sectional or longitudinal association between physical activity, sedentary activity, and depression in the National Longitudinal Survey of Children and Youth (NLSCY). Methods: These studies used both a stacked cross-sectional and a trajectory/latent class analysis design Univariate and multivariate multinomial logistic regressions were used to assess the relationship between physical and sedentary activity and depression using the emotional disorder-anxiety scale for children and youth available in the NLSCY. Results: When accounting for covariates, physically inactive respondents had increased odds of higher depressive symptom scores. Sedentary activity was only statistically significantly associated with depressive symptoms in the cross-sectional design. Conclusions: Physical inactivity is significantly associated to depressive symptomatology. The relationship between sedentary activity and depression is inconclusive.

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