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21
indicator of sedentary behavior may not be sufficient to understand the influence of
sedentary behavior on obesity.(13) They suggested that expanding the research definition
of ‘sedentary behavior’ to include other types of activities that clearly fall into this
category may increase the clinical relevance of sedentary behavior on adiposity.(13)
One major gap in the literatures on activity levels and overweight/obesity is that
most studies do not investigate both physical activity and sedentary behavior
simultaneously. Such consideration is important because not only these two behaviors are
distinct constructs that could coexist (see p.19), but also because the protective effects of
physical activity on heath could be attenuated by prolonged sedentary behavior.(57) For
example, one study showed that among highly-active individuals, those watching 4 hours
of TV per day were twice as likely to be overweight as those watching less than 1 hour of
TV per day.(179) Another gap is that growth and development is often not considered
when assessing effects of physical activity and sedentary behavior on weight status
during childhood and adolescence.(88) Puberty is a critical period of development with
dynamic changes in body composition(102) and activity levels.(79, 105, 162) It is
possible that maturation could affect the relationships between physical activity levels
and MetS. Lack of attention to the influence of pubertal stage may further confound
interpretations in youth studies. Therefore, the proposed Study 1 aims to fill these gaps by
including both physical activity and sedentary behavior in the same model, which allows
the investigation of their independent effects on overweight. In addition, pubertal
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 32 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 21 indicator of sedentary behavior may not be sufficient to understand the influence of sedentary behavior on obesity.(13) They suggested that expanding the research definition of ‘sedentary behavior’ to include other types of activities that clearly fall into this category may increase the clinical relevance of sedentary behavior on adiposity.(13) One major gap in the literatures on activity levels and overweight/obesity is that most studies do not investigate both physical activity and sedentary behavior simultaneously. Such consideration is important because not only these two behaviors are distinct constructs that could coexist (see p.19), but also because the protective effects of physical activity on heath could be attenuated by prolonged sedentary behavior.(57) For example, one study showed that among highly-active individuals, those watching 4 hours of TV per day were twice as likely to be overweight as those watching less than 1 hour of TV per day.(179) Another gap is that growth and development is often not considered when assessing effects of physical activity and sedentary behavior on weight status during childhood and adolescence.(88) Puberty is a critical period of development with dynamic changes in body composition(102) and activity levels.(79, 105, 162) It is possible that maturation could affect the relationships between physical activity levels and MetS. Lack of attention to the influence of pubertal stage may further confound interpretations in youth studies. Therefore, the proposed Study 1 aims to fill these gaps by including both physical activity and sedentary behavior in the same model, which allows the investigation of their independent effects on overweight. In addition, pubertal |
