Physical activity and sedentary behaviours in Hong Kong primary school children: Prevalence and gender differences

Participation of children with and without disabilities in home, school, and community in Hong Kong: A 2-year longitudinal study

Background

Children with disabilities are reported to participate less in activities than their typically developing peers. However, owing to limited longitudinal studies, improvements or deteriorations in their participation over time remain unclear. No studies were also conducted in Hong Kong to describe children’s activity participation over time.

Aim

To investigate the changes in participation patterns of Hong Kong children with and without disabilities.

Methods

Thirty-four children with disabilities and 138 without disabilities were recruited from four schools. Their parents completed the Participation and Environment Measure for Children and Youth twice over 2 years.

Results

After 2 years, both groups of children were found to engage more frequently in using electronic devices and less frequently in indoor play activities/games at home. They also participated more often in school extra-curriculum activities, events and field trips. However, the frequency of community activities remained relatively stable in the two groups. No changes in their levels of involvement in almost of home, school and community activities were identified.

Conclusion

The findings of increased participation in some home and school activities over time are encouraging. However, stable or possibly decreased participation of children with disabilities in other activities requires further efforts in promoting their participation.

Early-life activities mediate the association between family socioeconomic status in early childhood and physical fitness in early adolescence

The graded association between family socioeconomic status (SES) and physical fitness is evident, but little is known about the mechanism underlying this association. This study investigated the role of early-life activities as mediators of the longitudinal relationship between early-life SES and health-related physical fitness in 168 adolescents (51.2% boys; final mean age: 12.4 years old). In Wave 1 (2011–12), their parents completed questionnaires about family socioeconomic status (SES), parent–child activities, and child screen time. In Wave 2 (2014–15), participants’ physical activity levels were assessed through parent proxy-reports. In Wave 3 (2018–19), a direct assessment of handgrip strength, standing long-jump, and 6-min walk test (6MWT) performance was conducted. After controlling for demographic factors, results of mediation analyses revealed that (a) Wave 1 SES predicted Wave 3 long-jump and 6MWT performance; (b) child physical activity level in Wave 2 mediated the relation between Wave 1 SES and standing long-jump performance in Wave 3; and (c) recreational parent–child activities and child screen time in wave 1 mediated the relation between Wave 1 SES and 6MWT performance in Wave 3. Our findings suggest that the type and frequency of early-life activities play a role in the graded association between childhood SES and physical fitness in adolescence.

An Update on Physical Activity Research among Children in Hong Kong: A Scoping Review

Similar to their Western counterparts, children in Hong Kong generally fail to reach the recommended levels of physical activity (PA). As an ultra-dense metropolis, Hong Kong is different from most Western cities. It is therefore important to update and appraise previous PA research in order to inform future PA promotion for Hong Kong children. Using a scoping review, the current study aimed to evaluate PA research among preschool and school-aged children in Hong Kong aged 3-12 years old who are at a critical development stage. Literature was searched from four English databases: Medline via EBSCOhost, SPORTDiscus, ERIC and PsycINFO via ProQuest; and three Chinese databases: CNKI, CQVIP and WAN-FANG. PA research among Hong Kong children published from 1 January 1997 to the searching date, 31 March 2020 was included. A total of 63 studies were identified, with the majority of studies focused on school-aged children as compared to preschoolers, adopted a cross-sectional design, using self-reported PA measures, and with small to medium sample sizes. We classified eligible studies into five main categories: (a) Health benefits of PA (k = 12). Consistent evidence on the health benefits of skeletal and cardiovascular capacity, quality of life, cognitive function, and sleep quality was revealed. However, inconsistent evidence was found on the benefits of weight-related indicators and academic performance. (b) Patterns of PA (k = 12). There is a general pattern of low levels of PA among Hong Kong children, in particular girls and children with special educational needs. (c) Measures of PA and related constructs (k = 11). The Chinese versions of self-reported measures of PA, PA-related social environment, and PA-related psychological constructs showed acceptable reliabilities and validities. (d) Correlates of PA (k = 18). The correlates of PA include physical environment, social environment, physical factors, psychological factors, and multiple correlates, which is in line with the social-ecological model. (e) Interventions for promoting PA (k = 10). PA interventions among Hong Kong children were conducted for healthy children, children with special educational needs, and children with cancer. Overall, there is a growing volume of PA research among children in Hong Kong in the recent decade. Yet, there is a lack of high-quality research for measuring, understanding, and promoting PA among Hong Kong children. It is highly recommended that future PA research among children should pay more attention on the preschoolers, adopting robust research design (e.g., randomized controlled trials), recruiting large and representative sample, and collecting device-assessed data.

Age-period-cohort projection of trends in blood pressure and body mass index in children and adolescents in Hong Kong

Background

Blood pressure (BP) and body mass index (BMI) trends during childhood and adolescence are complex, making context-specific projections necessary to inform prevention and presage changes.

Objective

This study aimed to project BP and BMI in Hong Kong Chinese children and adolescents from 2015 to 2024 based on trends in BP and BMI observed from 1996/99 to 2014.

Methods

We decomposed recent trends into sex-specific contributions of age, period and cohort using age-period-cohort linear regression with Bayesian inference and autoregressive priors based on BP in children and adolescents aged 9–18 years from 1999 to 2014 and BMI in those aged 6–18 years from 1996 to 2014. We then used the resultant models to project BP and BMI from 2015 to 2024.

Results

During the study period, systolic BP decreased from 1999 to 2004/5 before gradually increasing to 2014 during childhood (for boys: from 104.6 to 101.9 and then to 103.4 mmHg) and during adolescence. Similar patterns were observed for diastolic BP. BMI generally increased from 1996 to 2009 before falling to 2014 during childhood (e.g. for boys: from 17.2 to 18.0 and then to 17.1 kg/m²). From 2015 onwards, systolic BP was projected to increase in girls, but remain stable in boys. For both sexes, diastolic BP was projected to increase, whereas BMI was projected to decrease to 2024.

Conclusions

In this economically developed Chinese setting, future trends in BP and BMI in children and adolescents are predicted to be divergent, consistent with prior discordant trends in BP and BMI.

Reliability of self-report measures of correlates of obesity-related behaviours in Hong Kong adolescents for the iHealt(H) and IPEN adolescent studies

BACKGROUND

This study examined the reliability of measures of correlates of dietary behaviours (DBs), physical activity (PA) and sedentary behaviour (SB) for Hong Kong adolescents.

METHOD

Individual, social and environmental correlates of obesity-related behaviours were assessed twice, 15-27 days apart (average 20 days), via self-administered questionnaires. These questionnaire included measures of decisional balance, self-efficacy, enjoyment and social support related to intake of fruits, vegetables, high-fat foods and sugar-sweetened beverages, PA behaviour and SB. They also included measures of perceived barriers to PA, parental rules related to PA and SB, and environmental correlates of DB, PA and SB. The questionnaires were self-completed outside school hours. A sample of 119 12-17 year old Chinese-speaking secondary school students (60 girls; 59 boys) were recruited from four Hong Kong schools located in areas stratified by walkability and socio-economic status.

RESULTS

The test-retest reliability of the examined measures ranged from poor to excellent (ICC: 0.30-0.99). All measures of correlates of PA and SB had excellent or substantial test-retest reliability, with the exception of self-efficacy for reducing SB (ICC: 0.59). Four of 18 measures of DBs showed moderate, and two poor (ICC < 0.41), test-retest reliability. Evidence of unidimensionality (Cronbach's α ≥ 0.70) was found for 10 of 28 multi-item scales. The evidence for the remaining 18 was either questionable or poor.

CONCLUSIONS

Most of the self-report measures of correlates of obesity-related behaviours used in the iHealt(H) study have acceptable test-retest reliability in Hong Kong adolescents. The factorial structure of several scales needs to be investigated in a larger sample.

Divergent secular trends in blood pressure and body mass index in children and adolescents in Hong Kong

Secular trends in blood pressure (BP) and body mass index (BMI) during childhood and adolescence are sentinels for the future population cardiovascular disease burden. We examined trends in BP z-score (ages 9-18 years from 1999 to 2014) and BMI z-score (ages 6-18 years from 1996 to 2014) in Hong Kong, China. Overall, BP z-score fell, systolic BP from 0.08 to -0.01 in girls and from 0.31 to 0.25 in boys. However, the trends were not consistent, for both sexes, systolic BP z-score was stable from 1999, decreased slightly from 2002 to 2005 and increased slightly to 2014, diastolic BP z-score decreased slightly from 1999 to 2004 and then remained stable to 2014. In contrast, BMI z-score rose from -0.15 to -0.01 in girls and from 0.14 to 0.34 in boys, mainly during 1997 to 2010. The upper tail of the systolic (except boys) and diastolic BP distribution shifted downwards, whereas the entire BMI distribution shifted upward. BP declined slightly whereas BMI rose in Hong Kong children and adolescents during the last 20 years, with systolic BP and BMI in boys above the reference. This warrants dual action in tackling rising BMI and identifying favorable determinants of BP, particularly targeting boys.

Factors of physical activity among Chinese children and adolescents: a systematic review

Background

Lack of physical activity is a growing problem in China, due to the fast economic development and changing living environment over the past two decades. The aim of this review is to summarize the factors related to physical activity in Chinese children and adolescents during this distinct period of development.

Methods

A systematic search was finished on Jan 10^th, 2017, and identified 2200 hits through PubMed and Web of Science. English-language published studies were included if they reported statistical associations between factors and physical activity. Adapted criteria from the Strengthening The Reporting of OBservational studies in Epidemiology (STROBE) statement and evaluation of the quality of prognosis studies in systematic reviews (QUIPS) were used to assess the risk of bias of the included studies. Related factors that were reported in at least three studies were summarized separately for children and adolescents using a semi-quantitative method.

Results

Forty two papers (published 2002–2016) were included. Most designs were cross-sectional (79%), and most studies used questionnaires to assess physical activity. Sample size was above 1000 in 18 papers (43%). Thirty seven studies (88%) showed acceptable quality by methodological quality assessment. Most studies reported a low level of physical activity. Boys were consistently more active than girls, the parental physical activity was positively associated with children and adolescents’ physical activity, children in suburban/rural regions showed less activity than in urban regions, and, specifically in adolescents, self-efficacy was positively associated with physical activity. Family socioeconomic status and parental education were not associated with physical activity in children and adolescents.

Conclusions

The studies included in this review were large but mostly of low quality in terms of study design (cross-sectional) and methods (questionnaires). Parental physical activity and self-efficacy are promising targets for future physical activity promotion programmes. The low level of physical activity raises concern, especially in suburban/rural regions. Future research is required to enhance our understanding of other influences, such as the physical environment, especially in early childhood.

Electronic supplementary material

The online version of this article (doi:10.1186/s12966-017-0486-y) contains supplementary material, which is available to authorized users.

Public Parks in Hong Kong: Characteristics of Physical Activity Areas and Their Users

Public parks, salient locations for engaging populations in health promoting physical activity, are especially important in high-density cities. We used the System for Observing Physical Activity in Communities (SOPARC) to conduct the first-ever surveillance study of nine public parks in Hong Kong (288 observation sessions during 36 weekdays and 36 weekend days) and observed 28,585 visitors in 262 diverse areas/facilities. Parks were widely used throughout the day on weekdays and weekend days and across summer and autumn; visitor rates were among the highest seen in 24 SOPARC studies. In contrast to other studies where teens and children dominated park use, most visitors (71%) were adults and seniors. More males (61%) than females used the parks, and they dominated areas designed for sports. Over 60% of visitors were observed engaging in moderate-to-vigorous physical activity, a rate higher than other SOPARC studies. Facilities with user fees were less accessible than non-fee areas, but they provided relatively more supervised and organized activities. Assessing parks by age, gender, and physical activity can provide useful information relative to population health. This study not only provides information useful to local administrators for planning and programming park facilities relative to physical activity, but it also provides a baseline for comparison by other high-density cities.

Longitudinal changes in objectively measured physical activity differ for weekdays and weekends among Chinese children in Hong Kong

Background

Cross-sectional investigation showed that Chinese children in Hong Kong were more physically active on weekends than weekdays, which is contrary to previous findings. However, little is known as to whether these time-segment-specific differences persist with age. This study aimed to compare the 2-year changes in accelerometer-assessed physical activity (PA) and sedentary time (ST) between weekdays and weekends among Chinese children in Hong Kong.

Methods

Children aged 6–8 years were recruited from primary schools in Hong Kong. Time spent in ST (<100 counts per minute [cpm]), moderate-to-vigorous PA (MVPA), and light-intensity PA (LPA) were measured by accelerometer at baseline and then at 1-year and 2-year follow-ups. Mean annual changes were determined using mixed-effects linear models for children who provided 3-day valid data (including 1 weekend day) for at least two time points (n = 412). Magnitude of changes between weekdays and weekends was compared using age × time-segment interactions.

Results

At each assessment wave, the percentage of time spent in MVPA (% MVPA) and LPA (% LPA) was consistently high, whereas the percentage of time spent in ST (% ST) was lower on weekends than weekdays. A decrease in % MVPA was found for both weekdays (mean annual change: boys, −0.7, 95 % CI = −0.9 to −0.1; girls, −0.8, 95 % CI = −1.0 to −0.6) and weekends (boys, −1.2, 95 % CI = −1.5 to −0.9; girls, −1.4, 95 % CI = −1.6 to −1.1). An increase was found in % ST for both weekdays (boys, 1.3, 95 % CI = 0.7 to 1.9; girls, 2.4, 95 % CI = 1.9 to 3.3) and weekends (boys, 1.8, 95 % CI = 1.1 to 2.5; girls, 2.6, 95 % CI = 1.9 to 3.3). Mean annual change in MVPA time (min) was greater on weekends than weekdays (difference: boys, 3.0, 95 % CI = 0.3 to 5.7; girls, 3.5, 95 % CI = 1.1 to 5.8).

Conclusions

Age-related decline in MVPA was more marked on weekends than weekdays. Interventions to hinder age-related changes in PA and ST should target both time segments, but weekends warrant particular attention for interventions targeting PA maintenance due to the greater declines.

The impact of cancer and its treatment on physical activity levels and behavior in Hong Kong Chinese childhood cancer survivors

BACKGROUND

Research indicates that regular physical activity is associated with numerous physiological and psychological health benefits for childhood cancer survivors. A review of the literature reveals that no study has so far examined the physical activity levels and behavior of Hong Kong Chinese childhood cancer survivors, and how the cancer and its treatment affect the physical activity and other behavior of these children remains unclear.

OBJECTIVE

The aims of this study were to assess the physical activity levels of Hong Kong Chinese childhood cancer survivors and to explore the factors that affect their adherence to and maintenance of regular physical activity.

METHODS

A cross-sectional study was used. A total of 128 childhood cancer survivors (9-16-year-olds) who underwent medical follow-up in the outpatient clinic were invited to participate in the study.

RESULTS

There was a significant decline in physical activity levels among childhood cancer survivors. Most of them did not take physical exercise regularly. Concern about academic performance, fatigue, and a decrease in physical strength and endurance after remission prevented them from engaging in regular physical activity.

CONCLUSIONS

This study indicates that many childhood cancer survivors did not engage in regular physical activity and that they overlooked or underestimated its importance.

IMPLICATIONS FOR PRACTICE

It is essential for nurses to correct misconceptions about physical activity among childhood cancer survivors and their parents and, most importantly, to advocate the principle of regular physical activity for these children, with the aim of enhancing their physical and psychological well-being.

Study on Current Levels of Physical Activity and Sedentary Behavior among Middle School Students in Beijing, China

Introduction

This study aimed to determine current levels of physical activity and sedentary behavior in middle school students on the basis of grade, sex, student attitudes toward physical education, and residence location.

Methods

In 2013, a cross-sectional study of 1793 students aged 12 to 15 years was conducted across eight middle schools in Beijing, China. Four schools were selected from an urban district and another four schools were from a suburban district. Physical activity and sedentary behavior data were collected using the commonly used school-based Chinese version of the China Health and Nutrition Survey.

Results

The mean age of sampled students was 13.3±1.0 years; 51.5% were boys. Approximately 76.6% of students reported having three 45-minute physical education classes every week. A total of 35.6% students spent ≥1 h/day performing moderate to vigorous physical activity (MVPA) during school, and 34.9% spent ≥1 h/day in MVPA outside school time. Approximately half (49.7%) of the students engaged in reading, writing, or drawing for ≥2 h/day, and 42.9% reported screen time for ≥2 h/day. Although boys spent more time engaged in physical activity than girls did, they also spent more time exhibiting sedentary behavior. Each 10-unit increase in attitudes toward physical education was associated with an increased odds of 1.15 (95%CI: 1.09–1.20) for spending more than 1 h/day on MVPA. Students in suburban schools reported engaging in physical activity less when compared with those in urban schools.

Conclusion

The majority of our students did not meet the current physical activity recommendations, and about half of the students spent excessive time engaging in sedentary behaviors. Findings from this study highlight a positive association between student attitudes toward physical education and physical activity. Studies are needed to further explore the role of student attitudes toward physical education in promoting physical activity among Chinese students.

Understanding neighborhood environment related to Hong Kong children's physical activity: a qualitative study using nominal group technique

BACKGROUND

Relationships between the neighborhood environment and children's physical activity have been well documented in Western countries but are less investigated in ultra-dense Asian cities. The aim of this study was to identify the environmental facilitators and barriers of physical activity behaviors among Hong Kong Chinese children using nominal group technique.

METHODS

Five nominal groups were conducted among 34 children aged 10-11 years from four types of neighborhoods varying in socio-economic status and walkability in Hong Kong. Environmental factors were generated by children in response to the question "What neighborhood environments do you think would increase or decrease your willingness to do physical activity?" Factors were prioritized in order of their importance to children's physical activity.

RESULTS

Sixteen unique environmental factors, which were perceived as the most important to children's physical activity, were identified. Factors perceived as physical activity-facilitators included "Sufficient lighting", "Bridge or tunnel", "Few cars on roads", "Convenient transportation", "Subway station", "Recreation grounds", "Shopping malls with air conditioning", "Fresh air", "Interesting animals", and "Perfume shop". Factors perceived as physical activity-barriers included "People who make me feel unsafe", "Crimes nearby", "Afraid of being taken or hurt at night", "Hard to find toilet in shopping mall", "Too much noise", and "Too many people in recreation grounds".

CONCLUSIONS

Specific physical activity-related environmental facilitators and barriers, which are unique in an ultra-dense city, were identified by Hong Kong children. These initial findings can inform future examinations of the physical activity-environment relationship among children in Hong Kong and similar Asian cities.

Development and reliability of a scale of physical-activity related informal social control for parents of Chinese pre-schoolers

Background

Parents’ perceived informal social control, defined as the informal ways residents intervene to create a safe and orderly neighbourhood environment, may influence young children’s physical activity (PA) in the neighbourhood. This study aimed to develop and test the reliability of a scale of PA-related informal social control relevant to Chinese parents/caregivers of pre-schoolers (children aged 3 to 5 years) living in Hong Kong.

Methods

Nominal Group Technique (NGT), a structured, multi-step brainstorming technique, was conducted with two groups of caregivers (mainly parents; n = 11) of Hong Kong pre-schoolers in June 2011. Items collected in the NGT sessions and those generated by a panel of experts were used to compile a list of items (n = 22) for a preliminary version of a questionnaire of informal social control. The newly-developed scale was tested with 20 Chinese-speaking parents/caregivers using cognitive interviews (August 2011). The modified scale, including all 22 original items of which a few were slightly reworded, was subsequently administered on two occasions, a week apart, to 61 Chinese parents/caregivers of Hong Kong pre-schoolers in early 2012. The test-retest reliability and internal consistency of the items and scale were examined using intraclass correlation coefficients (ICC), paired t-tests, relative percentages of shifts in responses to items, and Cronbach’s α coefficient.

Results

Thirteen items generated by parents/caregivers and nine items generated by the panel of experts (total 22 items) were included in a first working version of the scale and classified into three subscales: “Personal involvement and general informal supervision”, “Civic engagement for the creation of a better neighbourhood environment” and “Educating and assisting neighbourhood children”. Twenty out of 22 items showed moderate to excellent test-test reliability (ICC range: 0.40-0.81). All three subscales of informal social control showed acceptable levels of internal consistency (Cronbach's α >0.70).

Conclusions

A reliable scale examining PA-related informal social control relevant to Chinese parents/caregivers of pre-schoolers living in Hong Kong was developed. Further studies should examine the factorial validity of the scale, its associations with Chinese children’s PA and its appropriateness for other populations of parents of young children.

Recreational screen-time among Chinese adolescents: a cross-sectional study

Background

Rapid urbanization in China has led to a proliferation of electronic entertainment media among youth. Prolonged screen time (ST; includes watching television and playing on computers, video game consoles, or mobile phones) is linked to poor health profiles. The aim of this study was to report recreational ST behaviors and ST correlates among Chinese adolescents living in two regions with different degrees of urbanization.

Methods

A cross-sectional, school-based survey (n = 3461 adolescents; aged 12–14 years old) living in inner-city Shanghai and a peri-urban region of Hangzhou. Students completed a questionnaire including family characteristics, daily ST, and information on family environment related to screen use. Recreational ST was categorized into two groups according to recommendations by the American Academy of Pediatrics (< or ≥2 h/day). Parents reported their own ST and also reported educational attainment as a proxy for socioeconomic status.

Results

ST was higher among boys than girls and on weekends than weekdays. Peri-urban girls were more likely to exceed 2 h/day ST compared to inner-city girls on weekends. Having a father with no university degree, mother’s TV viewing ≥2 h/day, no ST rules at home, and eating meals in front of the TV were associated with higher ST on both weekdays and weekends, and regional differences were found for weekend ST.

Conclusions

TV viewing and playing on the computer were the most prevalent ST behaviors among Chinese adolescents. Mobile phone playing was less prevalent but persistent throughout the week. More population-level surveillance and research is needed to monitor the trends in ST behaviors and to better understand the characteristics of those who are at risk.

Do children emotionally rehearse about their body image?

This study examined the association between propensity for emotional rehearsal, body image self-perception and weight status in Chinese Hong Kong pre-adolescents. Children 8-12 years of age (n = 278) completed measurement of body mass index, body image and emotional rehearsal. Multinomial regression analyses revealed that body mass index was positively associated with body image dissatisfaction and a significant predictor of body size estimation. However, only body size underestimation was associated with lower rehearsal tendencies. The prevalence of body image dissatisfaction and body size estimation was also reported for this population. Future research is suggested for greater understanding of emotional coping in body image dissatisfaction in young children.

Physical Activity Research in Hong Kong From 1987 to 2012

A comprehensive understanding of research on the physical activity (PA) of Hong Kong youth is necessary to develop specific and effective intervention strategies. This review summarizes existing evidence in studies on PA among the Hong Kong youth. An electronic literature search was conducted using MEDLINE, SPORTDiscus, ERIC, and HighWire database. Forty-five studies published from 1987 to 2012 were included in this review. The findings are presented in five categories, namely, health benefits of PA, participation in PA, assessment of PA, correlates of PA, and interventions to promote PA. The results indicate that PA among the youth in Hong Kong has attracted concern in the past decade. Specifically, extensive studies focused on the areas of health benefits of PA, participation in PA, and correlates of PA. Research into context-specific correlates of PA and tailored PA promotion programs for the Hong Kong youth is warranted in the future.

A microgeographic analysis of physical activity behavior within elementary school grounds

PURPOSE

There is little scholarship on physical activity among children within outdoor spaces and work is needed to advance the design of these spaces from "best practices" towards evidence-based design. This project examined how playground feature density relates to children's physical activity.

DESIGN

We used the System for Observing Play and Leisure Activity to observe children's physical activity.

SETTING

We observed children during school recess on 24 school grounds in the Denver metropolitan area of Colorado, in spring of 2010 and 2011.

SUBJECTS

A total of 31,069 observations were made from an estimated 9900 children aged 5 to 12. These were aggregated and analyzed in 397 playground zones.

MEASURES

We examined utilization, the number of children present in a particular activity zone during an observation, and the percentage of children engaged in moderate to vigorous physical activity as they relate to the density of constructed features on school playgrounds.

ANALYSIS

Ordinary least-squares linear regression model assessed the relationship between playground feature density and the utilization and moderate to vigorous physical activity.

RESULTS

Significant positive associations were observed between utilization and feature density among all children (β = .20; p < .001) and a statistically significant but small association was observed between moderate to vigorous physical activity and feature density for girls (β = .12; p = .013), but not for boys.

CONCLUSION

This analysis contributes to evidence that design features of play spaces may influence children's behavior within school grounds.

Correlates of physical activity and screen-based behaviors in Chinese children

OBJECTIVES

To investigate individual, behavioral, social and environmental correlates of physical activity (PA) and screen-based behaviors ([SBBs] TV viewing, electronic games playing and Internet use) in Chinese boys and girls in Hong Kong.

DESIGN

Cross-sectional study.

METHODS

PA and SBBs were self-reported among 303 children. Individual, behavioral, social and environmental correlates were reported by children and parents. Children's height and weight were measured and population density of residence districts was divided into tertiles. Hierarchical multivariable regression analyses were conducted to determine the contributions of correlates in explaining PA and SBBs.

RESULTS

Participation in school sport teams and self-efficacy was positively associated with PA in boys. Girls who reported participation in school sport teams, who perceived more peer support, had a more supportive home PA environment, and spent more time doing homework were more physically active. Family support for PA was negatively and homework was positively, associated with boys' SBBs. Body mass index and parent role modeling of TV was positively associated with TV viewing, whilst more sedentary opportunities in the home were associated with higher Internet use/e-games playing among girls.

CONCLUSIONS

Sex differences existed among the individual, behavioral, social and home environmental factors related to PA and SBBs. Interventions should consider multiple and sex-specific factors for promoting an active lifestyle and reducing sedentary time among Chinese children.

Association between television viewing and self-esteem in children

OBJECTIVE

Few studies have examined the effect of excess television (TV) viewing on specific mental health outcomes, such as self-esteem. We explored the cross-sectional association between TV viewing hours and self-esteem in young children.

METHODS

A total of 70,210 primary 4 (US grade 4) participants of the Department of Health Student Health Service, Hong Kong, in 1998-2000 reported TV viewing hours in a standardized questionnaire. Self-esteem was assessed using the Culture-Free Self-Esteem Inventories for Children (SEI) with 4 subscales. Multivariate linear regression yielded beta coefficients (β) for SEI subscale scores by TV hours, adjusting for age, sex, body mass index, lifestyle characteristics, and highest parental education and occupational status.

RESULTS

Only 10.9% of children watched >4 hours per day, while 45.3% watched TV for 1 to ≤2 hours per day. Compared with children who watched <1 hour of TV per day, those who watched a moderate amount (1 to ≤2 hours/day) had higher (more favorable) SEI scores in the General (β = 0.09; 95% confidence interval = 0.02-0.16), Social (0.05; 0.01-0.09), and Parent-Related (0.04; 0.00-0.08) subscales but lower scores in the Academic subscale (-0.06; -0.09 to -0.02). Children who watched >2 hours of TV per day had lower SEI scores than those who watched <1 hour per day in all 4 subscales.

CONCLUSIONS

An inverted J-shaped relation was observed between TV viewing hours and self-esteem among young children. The development of self-esteem among children who report little or excessive TV viewing should be further studied.

Reliability and validity of psychosocial and environmental correlates measures of physical activity and screen-based behaviors among Chinese children in Hong Kong

Background

Insufficient participation in physical activity and excessive screen time have been observed among Chinese children. The role of social and environmental factors in shaping physical activity and sedentary behaviors among Chinese children is under-investigated. The purpose of the present study was to assess the reliability and validity of a questionnaire to measure child- and parent-reported psychosocial and environmental correlates of physical activity and screen-based behaviors among Chinese children in Hong Kong.

Methods

A total of 303 schoolchildren aged 9-14 years and their parents volunteered to participate in this study and 160 of them completed the questionnaire twice within an interval of 10 days. Intraclass correlation coefficients (ICCs), kappa statistics, and percent agreement were performed to evaluate test-retest reliability of the continuous and categorical variables, respectively. Exploratory factor analyses (EFAs) were conducted to assess convergent validity of the emergent scales. Cronbach's alpha and ICCs were performed to assess internal and test-retest reliability of the emergent scales. Criterion validity was assessed by correlating psychosocial and environmental measures with self-reported physical activity and screen-based behaviors, measured by a validated questionnaire.

Results

Reliability statistics for both child- and parent-reported continuous variables showed acceptable consistency for all of the ICC values greater than 0.70. Kappa statistics showed fair to perfect test-retest reliability for the categorical items. Adequate internal consistency and test-retest reliability were observed in most of the emergent scales. Criterion validity assessed by correlating psychosocial and environmental measures with child-reported physical activity found associations with physical activity in the self-efficacy scale (r = 0.25, P < 0.05), the peer support for physical activity scale (r = 0.25, P < 0.05) and home physical activity environmental (r = 0.14, P < 0.05). Children's screen-based behaviors were associated with the family support for physical activity scale (r = -0.22, P < 0.05) and parental role modeling of TV (r = 0.12, P = 0.053).

Conclusions

The findings provide psychometric support for using this questionnaire for examining psychosocial and environmental correlates of physical activity and screen-based behaviors among Chinese children in Hong Kong. Further research is needed to develop more robust measures based on the current questionnaire, especially for peer influence on physical activity and parental rules on screen-based behaviors.

Prevalence of exercise and non-exercise physical activity in Chinese adolescents

Non-exercise physical activity (NEPA) is an important part of energy expenditure. This study aimed to investigate the prevalence of exercise and NEPA among adolescents. In the HKSOS project 2006-2007, the proportions of Hong Kong Chinese adolescents (N=32,005) achieving 60-minute exercise and 60-minute NEPA per day were analyzed. Exercise was defined as structured and planned physical activities, and NEPA was defined as unstructured and unplanned physical activities including walking for transportation and climbing stairs. The prevalence of exercise was higher in boys than girls (after school: 63.8% vs 39.6%; holidays: 78.7% vs 60.0%), but the prevalence of NEPA in boys was similar to that in girls (after school: 72.2% vs 68.0%; holidays: 80.3% vs 79.4%). In general, the prevalence of both exercise and NEPA decreased with age in boys and girls, but was more marked for exercise than NEPA. In conclusion, the prevalence of exercise was lower in adolescent girls than boys, and decreased more rapidly with age than NEPA. NEPA seems to be easier to accumulate than exercise among adolescents regardless of sex and age.