Structured physical activity and psychosocial correlates in middle-school girls

OBJECTIVE: Little is known about the types of physical activity (PA) in which adolescent girls participate. Understanding this, along with examining specific psychosocial correlates of PA, may help guide the development of effective interventions to prevent the decline in PA in female youth. METHODS: 2791 sixth grade girls participating in the Trial of Activity for Adolescent Girls from six geographical locations completed surveys assessing participation in sports teams and activity classes/lessons in and out of school, self-efficacy for PA, PA enjoyment, physical education (PE) enjoyment, and perceived school climate for girls' PA (data collection: January-May 2003). Correlates of girls' participation in structured PA and sociodemographic differences were explored. RESULTS: 89.5% of girls participated in structured PA: 39% at school and 86% outside of school. Across race/ethnicity, most reported activities were basketball (44%), cheerleading/dance (41%), and swimming (39%). Controlling for socioeconomic status, geographical location, and race/ethnicity, girls with a higher self-efficacy (OR=3.44, CI=1.72-6.92) and higher enjoyment of PE class (OR=1.97, CI=1.25-3.120) were more likely to participate in structured PA. PA enjoyment and perceived school climate for girls' PA were not associated with participation in structured PA. CONCLUSION: Interventions that increase self-efficacy and enjoyment of PE could result in greater participation in structured PA and higher overall PA levels among adolescent girls.     

Psychosocial Factors Influencing Calcium Intake and Bone Quality in Middle School Girls

Calcium intake has been associated with promoting bone health in children and adolescents, thus preventing osteoporosis later in life. Behavior change such as increased calcium intake, as well as physiological factors such as bone quality, may be facilitated by psychosocial and environmental factors. The purpose of this study was to identify pathways by which psychosocial factors influence calcium intake and bone quality in middle school girls. The study design was cross-sectional. Baseline data from the Incorporating More Physical Activity and Calcium in Teens (IMPACT) study, collected in 2001-2003, were used. IMPACT was a 1.5-year nutrition and physical activity intervention study, designed to improve bone density in 717 middle school girls in Texas. Main outcome measures were calcium intake determined using mean milligrams of calcium consumed per day and number of glasses of milk consumed per day, and bone quality determined using a calcaneal stiffness index. Confirmatory factor analysis and path analysis were performed to identify the direct and indirect pathways used by various psychosocial factors such as knowledge, self-efficacy, outcome expectations, and milk availability at home, to influence calcium intake and bone quality. Results showed that knowledge of osteoporosis and calcium-rich foods had an indirect effect on calcium intake, with outcome expectations as the mediating variable (β=.035 and β=.03, respectively; P<0.05). Calcium self-efficacy had a significant indirect effect on calcium intake, with outcome expectations as the mediator (β=.085, P<0.05). None of the variables significantly influenced bone quality. Thus, several direct and indirect pathways used to influence calcium intake among adolescent girls were identified. These findings are critical for the development of effective interventions to promote calcium intake in this population.     

Factorial invariance and latent mean structure of questionnaires measuring social-cognitive determinants of physical activity among black and white adolescent girls.

BACKGROUND: We previously developed questionnaires based on contemporary theories to measure physical activity determinants among youth [Motl et al., Prev Med 2000; 31:584-94]. The present study examined the factorial invariance and latent mean structure of unidimensional models fit to the questionnaires measuring attitude, subjective norm, perceived behavioral control, and self-efficacy about physical activity among black and white adolescent girls. METHODS: Black (n = 896) and white (n = 823) girls in the 8th grade completed the questionnaires measuring attitude, subjective norm, perceived behavioral control, and self-efficacy about physical activity. The responses were subjected to analyses of factorial invariance and latent mean structure using confirmatory factor analysis with full-information maximum likelihood estimation in AMOS 4.0. RESULTS: The unidimensional models of the four questionnaires generally demonstrated invariance of the factor structure, factor loadings, and factor variance across race but not invariance of the variance-covariance matrices or item uniquenesses. The analyses of latent mean structure demonstrated that white girls had higher latent mean scores on the measures of attitude and self-efficacy than black girls; there were similar, but smaller, differences between white and black girls on the measures of subjective norm and perceived behavioral control. CONCLUSIONS: The questionnaires can be employed in interventions to test the mediating influences of attitude, subjective norm, perceived behavioral control, and self-efficacy on participation in physical activity by black and white adolescent girls.     

Self-efficacy partially mediates the effect of a school-based physical-activity intervention among adolescent girls

BACKGROUND: This study evaluated the effects of the Lifestyle Education for Activity Program (LEAP), a comprehensive school-based intervention emphasizing changes in instruction and school environment, on variables derived from social-cognitive theory (SCT) as mediators of change in physical activity among black and white adolescent girls. METHODS: Twenty-four high schools paired on enrollment size, racial composition, urban, suburban, or rural location, and class structure were randomized into control (n = 12) or experimental (n = 12) groups. There were 1038 girls in the control group and 1049 girls in the experimental group. The multicomponent intervention emphasized the enhancement of self-efficacy and development of behavioral skills by using curricular activities within physical education classes and health education instruction. The primary outcomes were self-efficacy, outcome-expectancy value, goal setting, satisfaction, and physical activity. RESULTS: Latent variable structural equation modeling indicated that: (1) self-efficacy and satisfaction exhibited synchronous, cross-sectional relationships with physical activity; (2) the intervention had direct effects on self-efficacy, goal setting, and physical activity; and (3) self-efficacy partially mediated the effect of intervention on physical activity. CONCLUSIONS: To our knowledge, this study provides the first evidence from a randomized controlled trial that manipulation of self-efficacy results in increased physical activity among black and white adolescent girls. The results encourage the use of self-efficacy as a targeted, mediator variable in interventions designed to increase physical activity among girls.     

Differences in physical activity between black and white girls living in rural and urban areas

This study examined the relationship of race and rural/urban setting to physical, behavioral, psychosocial, and environmental factors associated with physical activity. Subjects included 1,668 eighth-grade girls from 31 middle schools: 933 from urban settings, and 735 from rural settings. Forty-six percent of urban girls and 59% of rural girls were Black. One-way and two-way ANOVAs with school as a covariate were used to analyze the data. Results indicated that most differences were associated with race rather than setting. Black girls were less active than White girls, reporting significantly fewer 30-minute blocks of both vigorous and moderate-to-vigorous physical activity. Black girls also spent more time watching television, and had higher BMIs and greater prevalence of overweight than White girls. However, enjoyment of physical education and family involvement in physical activity were greater among Black girls than White girls. Rural White girls and urban Black girls had more favorable attitudes toward physical activity. Access to sports equipment, perceived safety of neighborhood, and physical activity self-efficacy were higher in White girls than Black girls.     

Prevalence and correlates of physical activity behaviors among elementary schoolchildren in multiethnic, low income, inner-city neighborhoods in Montreal, Canada.

PURPOSE: To describe the prevalence and correlates of physical inactivity and of participation in organized sports at and outside school among elementary schoolchildren in multiethnic, low income, urban neighborhoods in Montreal, Canada. METHODS: As part of the evaluation of a school-based heart health promotion program, baseline data on physical activity behaviors and potential correlates of these behaviors, were collected from 2285 students aged 9-13 in all 130 grade 4 to 6 classes in 24 inner-city elementary schools from May to June 1993. RESULTS: One-fifth of boys (20.5%) and 24.4% of girls were inactive; 40.0% and 33.3% of boys and girls respectively, participated in school sports teams; 82.5% and 74.7% participated in organized sports outside school. Declines in activity levels with age were apparent in both genders. Children who participated in organized sports programs at and outside school, those with higher perceived self-efficacy for physical activity, and those with more parental support for engaging in physical activity were more active. Children of Asian family origin were less active. Socioeconomic status was related to participation in organized sports outside school. CONCLUSIONS: To reach children in socio-economically disadvantaged areas and to prevent age-related declines in activity levels, interventions promoting physical activity should focus on increasing availability and access to community-based organized sports programs at and outside school. Also they should include components to increase parental support and to improve perceived self-efficacy for physical activity.     

Psychosocial correlates of physical activity in white and African-American girls.

PURPOSE: To evaluate the relative utility of the Theory of Reasoned Action (TRA) and the Theory of Planned Behavior (TPB) in explaining intentions and physical activity behavior in white and African-American eighth-grade girls. METHODS: One-thousand-thirty white and 1.114 African-American eighth-grade girls (mean age 13.6 +/- 0.7 years) from 31 middle schools in South Carolina completed a 3-day physical activity recall and a questionnaire assessing attitudes, subjective norms, perceived behavioral control, self-efficacy, and intentions related to regular participation in moderate-to-vigorous physical activity (MVPA). RESULTS: Among Whites, 17% of the variance in intentions was contributed by subjective norms and attitude, with intentions accounting for 8% of the variance in MVPA. The addition of perceived behavioral control and self-efficacy to the TRA significantly improved the prediction of intentions and MVPA accounting for 40% and 10% of the variance, respectively. Among African-Americans, subjective norms and attitude accounted for 13% of the variance in intentions, with intentions accounting for only 3% of the variance in MVPA. The addition of perceived behavioral control and self-efficacy to the TRA significantly improved the prediction of intentions and MVPA accounting for 28% and 5% of the variance, respectively. CONCLUSIONS: The results provided limited empirical support for the TPB among white adolescent girls; however, our findings suggest that the planned behavior framework has limited utility among African-American adolescent girls. The relatively weak link between intentions and MVPA observed in both population groups suggest that constructs external to the TPB may be more important mediators of physical activity behavior in adolescent girls.     

Interactive multimedia for promoting physical activity (IMPACT) in children

OBJECTIVE: To develop and examine the efficacy of a computer-based interactive multimedia curriculum for promoting physical activity in fourth grade children. RESEARCH METHODS AND PROCEDURES: The participants were 209 fourth grade children (mean age of 9.5 +/- 0.4 years) from four schools. Two schools received an 8-week multimedia intervention delivered by interactive CD-ROM, supplemented by four classroom and four homework assignments. Two control schools received educational CD-ROMS not related to health outcomes. Measures conducted before and after intervention included height, weight, percentage body fat (bioimpedance analysis), physical activity (5-day accelerometry), and psychosocial aspects of physical activity by questionnaire. All outcomes were examined using general linear models. RESULTS: There was a significant treatment effect for obesity reduction in girls but not in boys. There were no significant treatment effects on total physical activity by accelerometry (total counts per minute), but there was an overall treatment effect on reducing percent of time in moderate-intensity activity (16.5% to 15% of the time) and significant sex-by- treatment interactions for light-intensity activities (reduction in boys from 78% to 75% of the time and an increase in girls from 78% to 81% of the time). There were marginal/significant treatment effects for improvements in behavioral outcomes, including self-efficacy (p = 0.06), social norms (p = 0.07), and outcome expectancies (p = 0.049). DISCUSSION: The interactive multimedia curriculum favored an improvement in obesity indices in girls and was associated with subtle changes in physical activity in girls and general improvement in psychosocial outcomes related to physical activity.     

Physical Activity and Sports Team Participation: Associations With Academic Outcomes in Middle School and High School Students

BACKGROUND: Previous studies have found that higher physical activity levels are associated with greater academic achievement among students. However, it remains unclear whether associations are due to the physical activity itself or sports team participation, which may involve requirements for maintaining certain grades, for example. The purpose of this study is to examine the associations between sports team participation, physical activity, and academic outcomes in middle and high school students. METHODS: Data were drawn from Project EAT (Eating Among Teens), a survey of middle and high school students (n = 4746). Students self-reported their weekly hours of physical activity, sports team participation, and academic letter grades. Two statistical models were considered: first, 2 separate regression analyses with grade point average (GPA) as the outcome and either sports team participation or physical activity as the predictor; second, a single regression with GPA as the outcome and both sports team participation and physical activity as the simultaneous predictors. RESULTS: For high school girls, both physical activity and sports team participation were each independently associated with a higher GPA. For high school boys, only sports team participation was independently associated with a higher GPA. For middle school students, the positive association between physical activity and GPA could not be separated from the relationship between sports team participation and a higher GPA. CONCLUSIONS: Regardless of whether academic success was related to the physical activity itself or to participation on sports teams, findings indicated positive associations between physical activity involvement and academic achievement among students.     

The Health Indicators Associated With Screen-Based Sedentary Behavior Among Adolescent Girls: A Systematic Review

PurposeEvidence suggests sitting time is independently associated with a range of health issues in adults, yet the relationship between sedentary behavior and health indicators in young people is less clear. Age-related increases in sedentary behavior are well-documented; the behavioral patterns of adolescent girls are of particular concern. More than one third of adolescent girls’ sedentary behavior time is accumulated through use of recreational screen-based behaviors. The objective of this review was to investigate the association between recreational screen-based sedentary behavior and the physical, behavioral, and psychosocial health indicators for adolescent girls. A secondary objective was to identify studies that have adjusted sedentary behavior indicators for physical activity.MethodsA structured electronic search of all publication years (through December 2011) was conducted to identify studies in: CINAHL, Communications and Mass Media Complete, ERIC, MEDLINE with Full Text, PsycINFO, and SPORTDiscus with Full Text. Included publications were observational and interventional studies involving adolescent girls (12–18 years) that examined associations between screen-based, sedentary behavior and health indicators (physical, psychosocial, and/or behavioral). The search identified 33 studies that evaluated health indicators of screen-based sedentary behaviors among adolescent girls.ResultsStrong evidence for a positive association between screen-based sedentary behavior and weight status was found. A positive association was observed between screen-time and sleep problems, musculoskeletal pain and depression. Negative associations were identified between screen time and physical activity/fitness, screen time and psychological well-being, and screen time and social support. The relationship between screen-based sedentary behavior and diet quality was inconclusive. Less than half of the studies adjusted sedentary behavior indicators for physical activity.ConclusionsScreen-based sedentary behavior is associated with a range of adverse health consequences, but additional longitudinal studies are needed to better understand the health impacts. In addition, screen-time guidelines for youth should be regularly revised and updated to reflect rapid technological changes.     

Gender Differences in Physical Activity and Determinants of Physical Activity in Rural Fifth Grade Children

ABSTRACT: This study determined if gender differences in physical activity could be accounted for by differences in selected social-cognitive determinants of activity behavior. Some 334 fifth grade, predominantly African-American students provided information regarding after-school physical activity and the hypothesized determinants of activity behavior. Boys reported significantly greater participation in vigorous (≥ 6 METs) and in moderate to vigorous (≥4 METs). Relative to girls, boys demonstrated higher levels of physical fitness, greater self-efficacy in overcoming barriers to physical activity, greater amounts of television watching, and higher levels of participation in community sports and physical activity organizations. When mean physical activity scores for girls and boys were adjusted for the effects of these determinant variables, the significant gender difference in physical activity remained. However, adjustment for self-efficacy in overcoming barriers and community sports reduced the gender gap by 5% and 7%, respectively. In contrast, adjustment for television watching increased the gender gap by about 8%. Results indicated perceived confidence in overcoming barriers to physical activity and participation in community physical activity programs are factors related to the gender difference in physical activity.     

Gender Differences in Physical Activity and Determinants of Physical Activity in Rural Fifth Grade Children

ABSTRACT: This study determined if gender differences in physical activity could be accounted for by differences in selected social-cognitive determinants of activity behavior. Some 334 fifth grade, predominantly African-American students provided information regarding after-school physical activity and the hypothesized determinants of activity behavior. Boys reported significantly greater participation in vigorous (≥ 6 METs) and in moderate to vigorous (≥4 METs). Relative to girls, boys demonstrated higher levels of physical fitness, greater self-efficacy in overcoming barriers to physical activity, greater amounts of television watching, and higher levels of participation in community sports and physical activity organizations. When mean physical activity scores for girls and boys were adjusted for the effects of these determinant variables, the significant gender difference in physical activity remained. However, adjustment for self-efficacy in overcoming barriers and community sports reduced the gender gap by 5% and 7%, respectively. In contrast, adjustment for television watching increased the gender gap by about 8%. Results indicated perceived confidence in overcoming barriers to physical activity and participation in community physical activity programs are factors related to the gender difference in physical activity.     

Social desirability is associated with some physical activity, psychosocial variables and sedentary behavior but not self-reported physical activity among adolescent males

This study examined whether controlling for social desirability improved the association between self-reported and objectively measured physical activity among adolescent males and the extent that psychosocial variables predict physical activity after controlling for social desirability. Participants (n=447) were 10- to 14-year old Houston Boy Scouts. Participants completed self-reports of physical activity, sedentary behavior, preferences, self-efficacy and social desirability and wore an MTI accelerometer for 3 days. Correlations were conducted among variables. Regression models were performed to examine the relationships between objectively measured (accelerometer) and self-reported physical activity, objectively measured physical activity and psychosocial variables and self-reports of physical activity and psychosocial variables. All models controlled for social desirability. There were weak associations between self-reported and objectively measured physical activity measures that were slightly improved after controlling for social desirability. Psychosocial variables were strongly associated with self-reports of physical activity, but weakly associated with accelerometer physical activity. Social desirability was positively associated with physical activity preferences (r=0.169) and self-efficacy (r=0.118) and negatively associated (r=-0.158) with self-reported sedentary behavior. Differences in the strength of relationships between self-reported and objectively measured physical activity and psychosocial variables were not a function of social desirability.     

Associations between the school environment and adolescent girls' physical activity

This paper explores school sports facility provision, physical education allocation and opportunities for physical activity and their association with the number of days adolescent girls participate in at least 60 min of moderate-vigorous physical activity per week (MVPAdays). Data were collected through self-administered questionnaires from Scottish secondary school girls (n = 1978) and head teachers (n = 123) participating in the Health Behaviour in School-aged Children 2005/06 study. The best predictor of adolescent girls' MVPAdays was hours allocated to PE in fourth year of secondary school (β = 0.27, 95% CI 0.06-0.48). Having shower facilities resulted in decreased MVPA (β = -0.51, CI -0.90 to -0.12), as did providing less than two team sports clubs (β = -0.69, CI -1.28 to -0.10), compared with schools who provided four or more. Compared with schools with no after school clubs, girls who attended schools with activities at least 1 day per week were likely to have increased MVPAdays. PE allocation and extra-curricular clubs are likely to be of greater importance to girls' participation than school facilities per se. This study demonstrates how schools can maximize their environment to increase girls' PA and offers encouraging findings for those with limited sports facilities.     

Physical activity patterns in a diverse population of women

BACKGROUND: Demographic and psychosocial correlates of activity in domains other than recreational activity have not been well characterized and may be particularly relevant for health promotion efforts aimed at women. METHODS: Cross-sectional relationships between recreational, occupational, and household/caregiving physical activity and demographic and psychosocial factors were assessed with a mail survey in a random sample of 2,636 ethnically diverse women members of a large health maintenance organization, ages 20-65. Activity was assessed with a modified Baecke questionnaire that uses categorical responses regarding frequency of domain-specific activities to create four semicontinuous activity indices (sports/exercise, active living, occupational, household/caregiving). RESULTS: Multivariable logistic regression analysis showed that the likelihood of being in the highest quartile of the sports/exercise and active-living indices, compared with the other three quartiles, was decreased among older, nonwhite, less well educated, heavier women who had young children at home, lacked motivation to exercise, and perceived external obstacles to exercise behavior. The odds ratios (ORs) ranged from 0.38, 95% confidence interval (CI) 0.33-0.45, associated with low motivation, to 0.95, 95% CI 0.93-0.98, associated with increasing body mass index. Social support and confidence in one's ability to continue to exercise, even when faced with other pressures and demands (termed self-efficacy), were associated with increased likelihood of high levels of sports/exercise and active living (OR = 2.34, 95% CI 1. 83-2.98 and OR = 3.96, 95% CI 2.92-5.38, respectively). In contrast, the highest quartile of household/caregiving activity was positively associated with increasing age (OR = 1.28, 95% CI 1.16-1.42), Hispanic ethnicity (OR = 1.58, 95% CI 0.55-1.01), being married (OR = 1.70, 95% CI 1.33-2.18), having young children at home (OR = 6.99, 95% CI 4.33-11), and greater time constraints as a barrier to exercise (OR = 1.55, 95% CI 1.38-1.74) and was negatively associated with employment (OR = 0.38, 95% CI 0.30-0.47). Increased likelihood of the highest quartile of occupational activity was associated with high school education or less (OR = 2.26, 95% CI 1.74-2.94) and current smoking (OR = 1.66, 95% CI 1.23-2.23), while self-efficacy regarding exercise was associated with decreased likelihood (OR = 0. 77, 95% CI 0.61-0.96). CONCLUSIONS: These findings suggest that demographic and psychosocial correlates of physical activity vary by domain and that initiatives to promote physical activity in the population need to take these differences into account.     

Physical activity among African American and Latino middle school girls: consistent beliefs, expectations, and experiences across two sites

Physical inactivity is a major public health concern. Low levels of physical activity are reported in many subgroups of women including adolescent girls. More data are needed to better understand factors related to physical activity participation in adolescent girls. Therefore, we explored adolescent girls' reasons for participating and not participating in physical activity. Two independent samples were taken in California and Texas; the total sample included thirty-four African American and Latino girls. Six focus groups were conducted by trained facilitators. Based on independent qualitative analyses, six replicated themes emerged from the focus groups. Fun, social support, and concern with body image facilitated participation in activity. In contrast, negative experiences in physical education classes, concerns about appearance after activity, and lack of opportunity impeded participation in activity. Overall, the girls showed an interest in physical activity and identified activity motivators and barriers. We discuss the implications of our findings for future research.     

Limiting Postpartum Weight Retention in Culturally and Linguistically Diverse Women: Secondary Analysis of the HeLP-her Randomized Controlled Trial

Postpartum weight retention (PPWR) contributes to maternal obesity development and is more pronounced in culturally and linguistically diverse (CALD) women. Our antenatal healthy lifestyle intervention (HeLP-her) demonstrated efficacy in reducing PPWR in non-Australian-born CALD women compared with Australian-born women. In this secondary analysis, we aimed to examine differences in the intervention effect on behavioral and psychosocial outcomes between Australian-born and non-Australian-born women and explore factors associated with the differential intervention effect on PPWR. Pregnant women at risk of gestational diabetes (Australian-born n = 86, non-Australian-born n = 142) were randomized to intervention (four lifestyle sessions) or control (standard antenatal care). PPWR was defined as the difference in measured weight between 6 weeks postpartum and baseline (12–15 weeks gestation). Behavioral (self-weighing, physical activity (pedometer), diet (fat-related dietary habits questionnaire), self-perceived behavior changes), and psychosocial (weight control confidence, exercise self-efficacy, eating self-efficacy) outcomes were examined by country of birth. Multivariable linear regression analysis was conducted to assess factors associated with PPWR. The intervention significantly increased self-weighing, eating self-efficacy, and self-perceived changes to diet and physical activity at 6 weeks postpartum in non-Australian-born women, compared with no significant changes observed among Australian-born women. Intervention allocation and decreased intake of snack foods were predictors of lower PPWR in non-Australian-born women. Results indicate that the HeLP-her intervention improved dietary behaviors, contributing to the reduction of PPWR in CALD women. Future translations could prioritize targeting diet while developing more effective strategies to increase exercise engagement during pregnancy in this population.     

PHYSICAL ACTIVITY IN YOUNG AFRICAN AMERICAN WOMEN

African American women are reported to be less physically active than other population groups. This study examined personal behavioral and psychosocial and environmental factors associated with physical activity in African American women living at or below poverty. Most participants engaged in some moderate physical activity through housework and child care; 71% engaged in activity such as walking from one to seven times per week; but only 5% were vigorously active. Seventy-seven percent were active in the past, but 80% dropped out within 6 months, citing "lack of time and feeling bad" as the main reasons. Exercise self-efficacy was positively correlated with beliefs about physical and social outcomes of activity, with more active than inactive women believing that physical activity had more physical health outcomes. One-third of the women reported that family or friends disapproved of their spending time being physically active, and 45% had never been encouraged to be active by a health professional. However, health professionals' influence was positively correlated with weight reduction but not physical activity participation.     

Children’s School-Related Food and Physical Activity Behaviors Are Associated with Body Mass Index

Childhood obesity is a critical public health issue, with prevalence rates reaching nearly one in five children. Schools may be a promising public policy intervention point. The foods schools sell and the physical activity environments they foster can influence dietary behaviors and overall physical activity. Using secondary data from a nationally representative sample of children from the kindergarten class of 1998-1999 and nonexperimental methods, this study examines the associations between the food and physical activity environments in school and body mass index (BMI) for low-income boys and girls in the 8th grade during 2007. Results reveal that participating in school sports is associated with a 0.55 lower BMI score for boys. For low-income girls, eating the school breakfast is associated with a 0.70 higher BMI score and eating the school lunch is associated with a 0.65 higher BMI score. Each hour spent on homework is associated with a 0.02 higher BMI score for low-income girls. These findings suggest that schools may influence adolescent BMI and that there is room for improvement in school food and physical activity environments to promote healthier weights for low-income boys and girls.     

Bone mass status of school-aged children in Taiwan assessed by quantitative ultrasound: the Nutrition and Health Survey in Taiwan Elementary School Children (NAHSIT Children 2001-2002)

Bone health status in childhood and adolescence may be important factors influencing the attainment of peak bone mass. The Nutrition and Health Survey in Taiwan Elementary School Children 2000-2001 was carried out to evaluate the overall nutrition and health status of school children aged between 6 and 13 years. The survey was conducted using a multi-stage complex sampling scheme. Townships and city districts in Taiwan were classified into 13 strata. Bone mass measured as broadband ultrasound attenuation was taken at heel by quantitative ultrasound bone densitometry. A total of 1164 boys and 1016 girls who had complete physical examination data with ultrasound bone scan were included in the current analysis. There were no apparent differences in BUA across all strata for both genders. In both boys and girls, age, height, body weight, BMI, and intake frequencies of vegetables and fruits/juices were significantly related to BUA. Results of multivariate regression showed that age (beta=1.36, p=0.0002) and body weight (beta=0.40, p<0.0001) were significant predictors for BUA in boys, whereas in girls body weight (beta=0.47, p<0.0001), height, (beta=0.20, p=0.01), dietary phosphorus intake (beta=-0.002, p=0.038), and frequency of fruit/juice intake (beta=0.15, p=0.029) remained statistically significant. The differential effects dietary intake variables on BUA in boys and girls may be in part due to the development of puberty. It would be necessary to include levels of physical activity in future analyses for better understanding factors influencing the development of peak bone mass in Taiwanese children.