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108
that these negative social and emotional consequences may discourage overweight girls
from being active and also may increase time spent in sedentary behaviors.(59, 147)
Physical factors may also contribute to the relationships between MetS and activity levels.
Studies have reported that overweight children have poorer physical abilities,(139) poorer
motor skills performance,(42) and lower physical fitness levels(2) compared to their
normal weight peers.
Following the same logic, youth with MetS (whom are usually overweight) may
have lower self-efficacy for physical activity, greater activity-related social/emotional
distress, or poorer physical competence and muscular strength, which may increase their
participation in sedentary activities and/or limit their engagement in physical activity.
Evidence supporting this claim were found in two cross-sectional studies. It has been
showed that youth with MetS had higher levels of stress-related serum cortisol,(217)
suggesting a potential link between greater chronic life stress and the presence of MetS.
Additionally, waist circumference and blood pressure, two individual MetS components,
have been found to be inversely associated with physical fitness in children.(17) Another
potential explanation of how MetS influences activity levels is related to leptin, an
adipocyte derived hormone that plays a central role in the regulation of energy.(174)
Higher leptin levels have been shown to be positively related to hours of TV viewing(71)
as well as negatively related to physical activity.(7, 11) In line with other pediatric(141)
and adult(72) studies, we found a higher level of leptin in youth with MetS than those
without (MetS: 27.42±7.32 ng/ml; Non-MetS: 12.76±8.84 ng/ml, p<0.001) in our
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 119 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 108 that these negative social and emotional consequences may discourage overweight girls from being active and also may increase time spent in sedentary behaviors.(59, 147) Physical factors may also contribute to the relationships between MetS and activity levels. Studies have reported that overweight children have poorer physical abilities,(139) poorer motor skills performance,(42) and lower physical fitness levels(2) compared to their normal weight peers. Following the same logic, youth with MetS (whom are usually overweight) may have lower self-efficacy for physical activity, greater activity-related social/emotional distress, or poorer physical competence and muscular strength, which may increase their participation in sedentary activities and/or limit their engagement in physical activity. Evidence supporting this claim were found in two cross-sectional studies. It has been showed that youth with MetS had higher levels of stress-related serum cortisol,(217) suggesting a potential link between greater chronic life stress and the presence of MetS. Additionally, waist circumference and blood pressure, two individual MetS components, have been found to be inversely associated with physical fitness in children.(17) Another potential explanation of how MetS influences activity levels is related to leptin, an adipocyte derived hormone that plays a central role in the regulation of energy.(174) Higher leptin levels have been shown to be positively related to hours of TV viewing(71) as well as negatively related to physical activity.(7, 11) In line with other pediatric(141) and adult(72) studies, we found a higher level of leptin in youth with MetS than those without (MetS: 27.42±7.32 ng/ml; Non-MetS: 12.76±8.84 ng/ml, p<0.001) in our |
