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110
opportunities for school-related physical activity such as their physical activity for travel
(e.g., walking to and from school) and required participation in physical education classes.
On the other hand, we did fund significant associations between MetS and sedentary
behavior. This may be due to the fact that there is generally more opportunity to
participate in attractive sedentary behaviors than in physical activity.(62) Perhaps, a more
pronounced decline in MVPA occurs among those with MetS as they enter early
adulthood and are no longer mandated to participate in school-based physical activities.
Thus, perhaps MetS-related increases in sedentary behavior manifest in early puberty,
while effects on MVPA could emerge in late adolescence or early adulthood.
When comparing the results by measurement method in this study (objectively and
subjectively measured activity levels), the significant findings regarding MetS and
activity levels were observed based on the accelerometry data only. It poses a challenge
to explain why there were no significant findings on MetS and activity levels based on
the 3DPAR data. One possible explanation lies in the bias introduced by the self-reported
nature of the 3DPAR. As the estimates obtained by 3DPAR are subjective, they are
influenced by respondent’s perception of fitness levels, social desirability, and memory
introducing larger between-subject variations in activity levels. These larger variations
could further have been exaggerated by the small size of our MetS sample, resulting in
unstable activity estimates. This explanation is supported by the activity patterns
demonstrated in Figure 4-2, where a more consistent trend of activity levels was
observed in the non-MetS group (N=48) but not in the MetS group (N=7). Collectively, it
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 121 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 110 opportunities for school-related physical activity such as their physical activity for travel (e.g., walking to and from school) and required participation in physical education classes. On the other hand, we did fund significant associations between MetS and sedentary behavior. This may be due to the fact that there is generally more opportunity to participate in attractive sedentary behaviors than in physical activity.(62) Perhaps, a more pronounced decline in MVPA occurs among those with MetS as they enter early adulthood and are no longer mandated to participate in school-based physical activities. Thus, perhaps MetS-related increases in sedentary behavior manifest in early puberty, while effects on MVPA could emerge in late adolescence or early adulthood. When comparing the results by measurement method in this study (objectively and subjectively measured activity levels), the significant findings regarding MetS and activity levels were observed based on the accelerometry data only. It poses a challenge to explain why there were no significant findings on MetS and activity levels based on the 3DPAR data. One possible explanation lies in the bias introduced by the self-reported nature of the 3DPAR. As the estimates obtained by 3DPAR are subjective, they are influenced by respondent’s perception of fitness levels, social desirability, and memory introducing larger between-subject variations in activity levels. These larger variations could further have been exaggerated by the small size of our MetS sample, resulting in unstable activity estimates. This explanation is supported by the activity patterns demonstrated in Figure 4-2, where a more consistent trend of activity levels was observed in the non-MetS group (N=48) but not in the MetS group (N=7). Collectively, it |
