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84
children, regardless of gender. All three studies found that the association between
physical activity and metabolic risk became non-significant after adjusting for
cardiorespiratory fitness, which has been shown to have stronger associations with the
prevention of MetS than physical activity.(8, 172) It should be noted that two(8, 172) of
these three studies did not control for body composition, an important confounder, when
examining the influence of physical activity on metabolic risk. Although physical fitness
was not assessed in the current study, our findings add to the limited number of studies
applying objective measures of physical activity to assess its influence on MetS in
minority youth. We showed that higher levels of MVPA are related to lower metabolic
risk and that this association persists even after body composition, sedentary behavior,
and other relevant covariates are included in the models.
In contrast to the growing number of studies on physical activity and the MetS, very
few have examined the role of sedentary behavior on metabolic health. In adults, time
spent watching television and using a computer has been shown to positively linked with
MetS.(53, 67) Very little research has been conducted in youth, and findings were
inconclusive. One study(57) found a trend for a positive association between
self-reported TV viewing and risk for MetS (p=0.053), after adjustment for physical
activity. Given that youth spend the majority of their time in sedentary behaviors and
inactivity,(92) more research is needed to understand how sedentary behavior is related to
MetS. This study is the first to show that sedentary behavior (as measured subjectively by
3DPAR) is positively associated with metabolic risk, independent of body composition.
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 95 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 84 children, regardless of gender. All three studies found that the association between physical activity and metabolic risk became non-significant after adjusting for cardiorespiratory fitness, which has been shown to have stronger associations with the prevention of MetS than physical activity.(8, 172) It should be noted that two(8, 172) of these three studies did not control for body composition, an important confounder, when examining the influence of physical activity on metabolic risk. Although physical fitness was not assessed in the current study, our findings add to the limited number of studies applying objective measures of physical activity to assess its influence on MetS in minority youth. We showed that higher levels of MVPA are related to lower metabolic risk and that this association persists even after body composition, sedentary behavior, and other relevant covariates are included in the models. In contrast to the growing number of studies on physical activity and the MetS, very few have examined the role of sedentary behavior on metabolic health. In adults, time spent watching television and using a computer has been shown to positively linked with MetS.(53, 67) Very little research has been conducted in youth, and findings were inconclusive. One study(57) found a trend for a positive association between self-reported TV viewing and risk for MetS (p=0.053), after adjustment for physical activity. Given that youth spend the majority of their time in sedentary behaviors and inactivity,(92) more research is needed to understand how sedentary behavior is related to MetS. This study is the first to show that sedentary behavior (as measured subjectively by 3DPAR) is positively associated with metabolic risk, independent of body composition. |
