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103
accelerometry variable. Half-hour blocks spent watching television/movies, playing video
games/surfing the internet, and talking on phone were coded separately as sedentary
behaviors. Daily total time spent in MVPA and sedentary behavior was obtained by
summing over the half-hour blocks over one day. Mean minutes per day was then
obtained by averaging total minutes across three days.
Statistical Analysis
Attrition is a common problem in longitudinal analysis. To assess the impact of
attrition on our data, two sets of attrition analysis were performed. First, of participants
who completed their first annual visit, those with complete baseline data for all
measurements included in the present study (final analytical sample) were compared to
those with incomplete baseline data on demographic variables using independent samples
t-tests/Wilcoxon rank sum tests for continuous variables or chi-square tests/ Fisher’s
exact tests for categorical variables. In the final analytical sample, these same sets of
analyses were applied to compare participants who remained in the present study (from
visit 1-5) and participants who dropped out prior to the 5th visit. Participants were
dichotomized into those with and without MetS for descriptive analyses. Independent
samples t-tests/ Wilcoxon rank sum tests and chi-square tests/ Fisher’s exact tests were
conducted to compare demographic variables between these two groups.
Growth curve modeling was used to evaluate whether longitudinal trends (initial
level and slope) reflected by the repeated measurements of physical activity and
sedentary behavior differed by MetS status (yes/no) over the course of 12 months. An
Object Description
| Title | The vicious cycle of inactivity, obesity, and metabolic health consequences in at-risk pediatric populations |
| Author | Hsu, Ya-Wen |
| Author email | ywxxbirdy@yahoo.com; yawenhsu@usc.edu |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Preventive Medicine (Health Behavior) |
| School | Keck School of Medicine |
| Date defended/completed | 2011-03-09 |
| Date submitted | 2011 |
| Restricted until | Restricted until 26 Apr. 2012. |
| Date published | 2012-04-26 |
| Advisor (committee chair) |
Chou, Chih-Ping Spruijt-Metz, Donna |
| Advisor (committee member) |
Unger, Jennifer B. Azen, Stanley Paul Palinkas, Lawrence A. |
| Abstract | PURPOSE: This dissertation examined the associations between physical activity, sedentary behavior, overweight, and the metabolic syndrome (MetS) in at-risk pediatric populations in the United States and in China. Study 1 identified the independent influences of physical activity, sedentary behavior, and other weight-related correlates on overweight status in Chinese youth. Study 2 explored the influences of physical activity and sedentary behavior on MetS in US minority youth. Study 3 compared the longitudinal trends of physical activity and sedentary behavior between youth with and without MetS in a sample of US minority female youth.; METHODS: Participants were youth (ages 8-18 years) in the United States and in China. Study 1 used baseline data from of a longitudinal smoking prevention and health promotion study conducted in the 7 large cities in China for Chinese youth ages 11-18 years. Study 2 used baseline data from three related pediatric obesity studies that share a set of common methods and measures (US Latino and African American youth ages 8-18 years). Data for Study 3 are from a longitudinal, observation study for Latina and African American female youth ages 8-11 years at baseline.; RESULTS: In Study 1, Chinese youth were more likely to be overweight if they spent more time being sedentary, slept <7 hours/night, were male, were younger, participated more in vigorous physical activity, had higher levels of parental education, better self-perceived health status, a higher frequency of vegetable intake, and a lower frequency of sweet/fast food intake. In Study 2, lower levels of moderate-to-vigorous physical activity (by accelerometry) and higher levels of sedentary behavior (by 3-day physical activity recall) are associated with increased the metabolic risk independent of each other and body composition. In Study 3, a significant decline in MVPA and an increase in sedentary behavior were observed over one year. Sedentary behavior as measured by accelerometry increased 23.42 minutes/per quarterly visit, adding up to 93.68 minutes/per year more in youth with MetS than in those without.; CONCLUSION: Overweight-related correlates seem to play different roles in the Chinese culture than in Western cultures. Findings from this dissertation support a vicious cycle of increasing inactivity, obesity, and metabolic complications. These findings, coupled with longitudinal evidence of the effects of activity levels on obesity and MetS, suggests that physical activity and sedentary behavior could function as antecedents as well as consequences of overweight or MetS in youth. |
| Keyword | Chinese youth; metabolic syndrome; minority youth; obesity; physical activity; sedentary behavior |
| Geographic subject (country) | USA; China |
| Coverage date | 1970/2010 |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m3779 |
| Contributing entity | University of Southern California |
| Rights | Hsu, Ya-Wen |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | cisadmin@lib.usc.edu |
| Filename | etd-Hsu-4455 |
| Archival file | uscthesesreloadpub_Volume23/etd-Hsu-4455.pdf |
Description
| Title | Page 114 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 103 accelerometry variable. Half-hour blocks spent watching television/movies, playing video games/surfing the internet, and talking on phone were coded separately as sedentary behaviors. Daily total time spent in MVPA and sedentary behavior was obtained by summing over the half-hour blocks over one day. Mean minutes per day was then obtained by averaging total minutes across three days. Statistical Analysis Attrition is a common problem in longitudinal analysis. To assess the impact of attrition on our data, two sets of attrition analysis were performed. First, of participants who completed their first annual visit, those with complete baseline data for all measurements included in the present study (final analytical sample) were compared to those with incomplete baseline data on demographic variables using independent samples t-tests/Wilcoxon rank sum tests for continuous variables or chi-square tests/ Fisher’s exact tests for categorical variables. In the final analytical sample, these same sets of analyses were applied to compare participants who remained in the present study (from visit 1-5) and participants who dropped out prior to the 5th visit. Participants were dichotomized into those with and without MetS for descriptive analyses. Independent samples t-tests/ Wilcoxon rank sum tests and chi-square tests/ Fisher’s exact tests were conducted to compare demographic variables between these two groups. Growth curve modeling was used to evaluate whether longitudinal trends (initial level and slope) reflected by the repeated measurements of physical activity and sedentary behavior differed by MetS status (yes/no) over the course of 12 months. An |
