Introduction: Recent reports in exercise related bone research have shown increased bone mineral content (BMC) at the femoral neck for prepubescent children participating in exercise programs consisting of repeated drop landings from a height of 61 cm. Increases in BMC from this type of exercise are believed to be the result of both high rate and magnitude of loading at the proximal femur. However, the dynamic characteristics associated with these landings in children have not been studied. Purpose: To describe the dynamic characteristics of children during landing and to quantify the forces associated with an activity associated with increases in bone mass. Methods: 13 prepubescent children (males=8, females=5, age 9.3 �� 0.7 years) who had previously completed drop landings over a 7 month period as part of an exercise intervention to increase bone mass participated in this research. Each subject performed 100 drop landings onto a force plate from a height of 61 cm. Ground reaction forces and two-dimensional kinematic data were recorded. Hip joint reaction forces were calculated using inverse dynamics based on a four segment rigid body model. Vertical ground reaction force and displacement data were fit to two single degree of freedom models, the Voigt and standard linear solid (SLS). The goodness of fit was quantified using the standard deviation of the error (SDE) between the experimental and the predicted data. Results: Peak vertical ground reaction forces were 8.5 �� 2.2 (mean �� SD) body weights (BW) while hip joint reactions were 6.0 �� 1.8 BW. Loading rates for ground reaction forces during initial impact were in excess of 470 BW/s. Across 100 jump trials, ground reaction forces changed significantly for 5 subjects (4 increase, 1 decrease, p<0.05) but were unchanged as a group. The SLS and Voigt models replicated the displacement traces well (SDE=0.003 m and 0.001 m respectively). However, in fitting force data, the SLS outperformed the Voigt model (SDE=580 N and 493 N respectively), but slightly under-predicted peak forces by 13%. Conclusion: Comparing force characteristics from drop landing to force characteristics known to be osteogenic, we can see how drop landings contribute to the osteogenic stimulus. The models used to represent children during drop landing closely fit displacement data, but did not replicate the time history of the impact force peaks thought to be important to osteogenesis. Quantification of exercises known to increase bone mass provides a basis on which to develop and implement additional exercise interventions for the purpose of increasing bone mass. / Graduation date: 2000

Background: Decades of research indicate that physical activity is an important behavior for health promotion and disease prevention. Despite dissemination of these research findings, many American adults are sedentary. The rates for sedentary behavior vary by race/ethnicity and gender. Women and adults from minority groups are most likely to be sedentary. Research on adults who are physically active has identified several factors that predispose, enable, and reinforce this behavior. The presence of social support is one such factor. Purpose: The purpose of this study was to identify the nature and extent of social influence on physical activity in a nationally-representative sample of minority women. Methods: A telephone survey of 2912 women ages 40 and older from various racial/ethnic groups was conducted from July 1996 to June 1997. Information on physical activity as well as other preventive health behaviors was collected. Analysis: Descriptive analyses were done on physical activity levels (including an accumulation of household and occupational physical activity), physical activity-related social support (PASS), support network, and measures of social contact. Logistic regression was used to determine differences in PASS levels and physical activity. Linear Regression was used to determine the relationship between social influence and physical activity level. Results: Women with high levels of physical activity- related social support were more likely to meet recommended levels of physical activity. There was no difference by racial/ethnic group. An index of social influence was not a significant predictor or physical activity level among all women in the sample. Conclusion: While women with higher levels of specific support for physical activity were more likely to be physically active, a more general measure of social support did not predict level of physical activity. More research is needed in assessment of both physical activity and social support in this population. / Graduation date: 1999

Graduation date: 2000

Given the high risk of relapse during the first year of exercise involvement, it is important to determine the processes of self-motivation which enable novice exercisers to become long-term maintainers. This study was designed to extend previous Stages of Change (Prochaska & DiClemente, 1983) research by comparing the Possible Selves (Markus & Nurius, 1986) of individuals at different points within the Maintenance stage of exercise. Participants consisted of female university employees, spouses, and dependents age 35-59 years who volunteered for the study. Participants completed the Stage of Exercise Scale (SOES; Cardinal, 1995) and a self-administered form of the Possible Selves Inventory (Cross & Markus, 1991) which was adapted to address the exercise domain. Women classified by the SOES as being in the Maintenance stage of exercise V=92) were assigned to one of three groups based on the duration of their exercise maintenance (6 months-5 years, 6-10 years, and 11-20 years). The three maintenance groups were compared with regard to the number and category of open-ended and exercise-related possible selves and the self-efficacy and outcome expectancy associated with three focused selves (most important, exercise-related, and exercise-specific). The results indicated that the three maintenance groups did not differ significantly in their possible selves. These findings provide support for the current conceptualization of the Stages of Change Model (Prochaska & Di Clemente, 1983) and suggest that differences between novice and expert maintainers may be behavioral, rather than cognitive, in nature. Several implications for intervention design and suggestions for future research are discussed. / Graduation date: 1998

The purpose of this investigation was to determine the validity and reliability of the Nicholas Manual Muscle Tester (NMMT), a portable dynamometer, as a measure of the isometric strength in women with arthritis. Female subjects (N=13; 66 �� 13.89 yrs.) with arthritis were tested for isometric muscle strength on the shoulder and hip (abduction, adduction, flexion, extension). Subjects were tested on three separate days using NMMT and Kincom 500-H dynamometers. Each subject performed three maximal isometric contractions for each joint action. A visual analog pain scale was used to determine level of pain prior to testing. Reliability values based on intraclass correlations coefficients (R) ranged from .85 to .93., with the exception of shoulder abduction being .49. Validity was determined correlating the mean value of the NMMT score with corresponding Kincom isometric measure. Pearson product moment correlations ranged from (r) .02 to .86, with 4 of 8 values meeting .05 level of significance. Correlation coefficients for pain and isometric force values were inconclusive and ranged from -.305 to .218. Major conclusions were: a) NMMT had high test-retest reliability in this sample; b) NMMT provides little criterion evidence of validity with the Kincom for most movements of hip and shoulder; c) level of pain was not a significant factor in subject reliability. / Graduation date: 1995

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / Community Medicine / Master / Master of Philosophy

Background: Vitamin D deficiency is prevalent among Chinese adults in Hong Kong and ignorance and confusion about vitamin D is common throughout the Hong Kong population. Health literacy is a crucial factor that influences the health actions and outcomes of individuals; however, little is known about the relationship between health literacy and behavior of supplementing vitamin D through sunlight exposure. Objective: The aim of the current study was to identify the factors associated with the health literacy of Chinese older adults and to investigate the relationship between health literacy and the behavior of supplementing vitamin D through sunlight exposure. Method: From May 2011 to January 2012, a cross-sectional survey was conducted among cognitively intact Chinese adults aged 60 or above. Recruitment of participants was through 23 residential care homes and 7 elderly community centers. A questionnaire elicited demographic and health literacy information and explored their knowledge about vitamin D, their attitude towards sunlight exposure, and their behavior related to sunlight exposure. Linear regression identified the factors associated with the health literacy among Chinese older adults. Path analysis investigated the relationship between health literacy and the behavior of participants regarding sunlight exposure. Results: Participants and analysis included 648 Chinese adults. Among the population, respondents identified as having inadequate health literacy numbered 52.5%. Five factors, including age, marital status, educational attainment, residential status, and duration of living in residential care homes, had significant association with health literacy. In addition, health literacy had a direct relationship to respondents’ exposure to sunlight (direct effect = .075) and an indirect relationship through their knowledge about vitamin D and their attitude towards sunlight exposure (indirect effect = .015). However, knowledge about vitamin D and attitude towards sunlight exposure did not mediate the association between health literacy and behaviors concerning sunlight exposure. Discussion and Conclusion: The results of this study showed that not only age, marital status, and educational attainment affected health literacy but also residential status and duration of living in residential care homes offered an effect. The study revealed that health literacy had both a direct and indirect relationship to health behavior (e.g., supplementing vitamin D through sunlight exposure). Health care professionals should note the relationship between health literacy and health behavior. Health education intervention about vitamin D supplement should focus training on individuals’ health literacy rather than their knowledge about vitamin D or attitude towards sunlight exposure. / published_or_final_version / Nursing Studies / Master / Master of Philosophy

Background: Self-rated health is an important predictor of adverse health outcomes (e.g. mortality) and health service use. While intergenerational family capital has been considered as one of the most important social determinants of self-rated health, the role of grandparent-grandchild dyads in self-rated health has not been fully investigated. Further, little is known about the patterns of change in trajectories of the self-rated health of older rural Chinese adults, who constitute the largest ageing population in the world. Objectives: This study investigated the association between grandparent-grandchild family capital and the self-rated health of older adults in rural China, as well as the mediation role of the grandparent-parent relationship in the association between grandparent-grandchild family capital and self-rated health. The present study also examined the development trajectories of the self-rated health of older rural Chinese adults from the point of view of intergenerational relationship and socio-economic status. Methods: Data for this study are derived from the Well-Being of the Elderly in Anhui Province survey. A random sample of 1,715 adults aged 60 and older were interviewed in the rural Chaohu region in 2001. A total of 1391 and 1067 respondents participated in the 2003 wave and 2006 wave respectively. New respondents were recruited for the 2009 wave and 1224 respondents were interviewed in 2009. Based on the 2009 wave of the Chaohu survey, structural equation modeling was used to examine the direct effect of grandparent-grandchild family capital on the self-rated health of older adults and the mediation role of the grandparent-parent relationship. Based on the 2001, 2003 and 2006 waves of the Chaohu survey, general growth mixture modeling was used to examine the multiple underlying trajectory patterns of self-rated health as well as the antecedents of the latent class memberships. Results: The results showed that grandparent-grandchild family capital had a direct effect on the self-rated health of older adults in rural China. The results also showed that the grandparent-parent relationship played a partial mediation role in the association between grandparent-grandchild family capital and self-rated health. Further, a two-class model was chosen to interpret the underlying trajectory classes. The two trajectories were labeled “good but declining SRH class” and “poor and declining SRH class”. Discussion: The findings enriched our theoretical understanding of intergenerational family capital and its effects in a cultural context that emphasizes collectivism and intergenerational exchanges. The mediator role of the grandparent-parent relationship was also highlighted in the findings, which confirmed “grandchild-as-linkage” theory. Further, there are underlying multiple trajectory patterns of the self-rated health of rural older adults. Intergenerational relationship was an important antecedent of the latent classes of self-rated health trajectories in rural China. / published_or_final_version / Social Work and Social Administration / Doctoral / Doctor of Philosophy

Down’s syndrome is a common chromosomal disorder associated with intellectual disability, congenital anomalies and increased risk of a number of acquired diseases. Despite improvements in life expectancy due to improved medical care, clear health disparities still exist. Down’s syndrome remains an important cause of infant mortality and intellectual disability in Hong Kong and globally. Gaps in existing knowledge include an unknown prevalence of Down’s syndrome, especially amongst adults; unknown patterns of A&E and outpatient utilisation by people with Down’s syndrome; the applicability of international data on hospitalisations of people with Down’s syndrome to Hong Kong; and the current demand on Hong Kong’s public healthcare services by people with Down’s syndrome. This study uses Hospital Authority patient and healthcare episode data to identify people with Down’s syndrome alive in 2010. Data from the Hong Kong Census 2011 is then used to create an estimate of the age- specific point prevalence of Down’s syndrome in Hong Kong on 31/12/2010. The relative risk associated with Down’s syndrome of at least one admission is calculated. Age and gender stratified rates of A&E attendance, outpatient attendance and inpatient admissions for both the Down’s syndrome population and the general population are estimated and compared. Average length of stay is also calculated for both populations and compared. A negative binomial with log link regression model is used to examine the association between patient characteristics, including age, gender, ethnicity and known comorbidities, and admission factors, including admission type, admitting speciality, surgery and intensive care admission, on length of stay. Lastly, the proportion of Hospital Authority A&E attendances, outpatient attendances and inpatient admissions that are by people with Down’s syndrome is calculated. 2,144 people with Down’s syndrome were identified. The overall prevalence of Down’s syndrome on 31/12/2010 in Hong Kong was 3.00 per 10,000. It was highest in those aged under 5 years at 9.95 per 10,000 and decreased with age. Rates of A&E, outpatient attendance and inpatient admission were 2.0, 2.4 and 3.3 times higher respectively in the Down’s syndrome population compared to the general population. The Risk Ratio of at least one admission associated with Down’s syndrome was 2.59 (p<0.001). Factors significantly associated with increased length of stay included infant age group, known thyroid disease, known other circulatory malformation, non-emergency admission, surgery, admission to ICU and 3 or more known comorbidities. Known congenital heart disease and known epilepsy were significantly associated with a shorter length of stay. The overall proportion of A&E attendances, outpatient attendances and inpatient admissions that were by people with Down’s syndrome were 0.06%, 0.07% and 0.10% respectively. This study provides new knowledge on Down’s syndrome in Hong Kong which will be of use to those delivering and planning healthcare services for this population, and also to those providing genetic counselling on Down’s syndrome. At the same time, new questions are raised on morbidity, mortality and equity of healthcare access amongst people with Down’s syndrome. Further research is required to answer these questions and thus allow effective interventions for reducing morbidity and mortality in this population to be designed. / published_or_final_version / Public Health / Master / Master of Public Health