Dianne S. Ward

Validity of the computer science and applications (CSA) activity monitor in children

PURPOSE The purpose of this study was to evaluate the validity of the CSA activity monitor as a measure of childrens physical activity using energy expenditure (EE) as a criterion measure. METHODS Thirty subjects aged 10 to 14 performed three 5-min treadmill bouts at 3, 4, and 6 mph, respectively. While on the treadmill, subjects wore CSA (WAM 7164) activity monitors on the right and left hips. VO2 was monitored continuously by an automated system. EE was determined by multiplying the average VO2 by the caloric equivalent of the mean respiratory exchange ratio. RESULTS Repeated measures ANOVA indicated that both CSA monitors were sensitive to changes in treadmill speed. Mean activity counts from each CSA unit were not significantly different and the intraclass reliability coefficient for the two CSA units across all speeds was 0.87. Activity counts from both CSA units were strongly correlated with EE (r = 0.86 and 0.87, P < 0.001). An EE prediction equation was developed from 20 randomly selected subjects and cross-validated on the remaining 10. The equation predicted mean EE within 0.01 kcal.min-1. The correlation between actual and predicted values was 0.93 (P < 0.01) and the SEE was 0.93 kcal.min-1. CONCLUSION These data indicate that the CSA monitor is a valid and reliable tool for quantifying treadmill walking and running in children.

Physical activity and determinants of physical activity in obese and non-obese children

OBJECTIVE: To compare the physical activity (PA) patterns and the hypothesized psychosocial and environmental determinants of PA in an ethnically diverse sample of obese and non-obese middle school children.DESIGN: Cross-sectional study.SUBJECTS: One-hundred and thirty-three non-obese and 54 obese sixth grade children (mean age of 11.4±0.6). Obesity status determined using the age-, race- and gender-specific 95th percentile for BMI from NHANES-1.MEASUREMENTS: Objective measurements were collected of PA over a 7-day period using the CSA 7164 accelerometer: total daily counts; daily moderate (3–5.9 METs) physical activity (MPA); daily vigorous physical activity (≥6 METs; VPA); and weekly number of 5, 10 and 20 min bouts of moderate-to-vigorous physical activity (≥3 METs, MVPA). Self-report measures were collected of PA self-efficacy; social influences regarding PA, beliefs about PA outcomes; perceived PA levels of parents and peers, access to sporting and/or fitness equipment at home, involvement in community-based PA organizations; participation in community sports teams; and hours spent watching television or playing video games.RESULTS: Compared to their non-obese counterparts, obese children exhibited significantly lower daily accumulations of total counts, MPA and VPA as well as significantly fewer 5, 10 and 20 min bouts of MVPA. Obese children reported significantly lower levels of PA self-efficacy, were involved in significantly fewer community organizations promoting PA and were significantly less likely to report their father or male guardian as physically active.CONCLUSIONS: The results are consistent with the hypothesis that physical inactivity is an important contributing factor in the maintenance of childhood obesity. Interventions to promote PA in obese children should endeavor to boost self-efficacy perceptions regarding exercise, increase awareness of, and access to, community PA outlets, and increase parental modeling of PA.

Acculturation and overweight-related behaviors among Hispanic immigrants to the US: The National Longitudinal Study of Adolescent Health

Little is known about the factors underlying the striking increase in overweight occurring between first and second generation US immigrants. Using data from the National Longitudinal Study of Adolescent Health, this study addressed two goals. First, we determined which measures of acculturation (defined as the acquisition of dominant cultural norms by members of a non-dominant group) were important. Second, we determined how the acculturation process affected differences in overweight and its proximate determinants (e.g., physical activity, diet, and smoking) as immigrants acculturated to American society. In addition, we sought to elucidate the role of underlying structural factors (e.g., family income and crime) and acculturation factors (e.g., language spoken at home and proportion of foreign-born neighbors) in generation differences in overweight. Results showed clear structural and acculturation differences between foreign and US-born immigrants to the US. Foreign-born immigrants were more likely to have lower family income and maternal education, and to live in areas of higher immigrant density and greater linguistic isolation. In addition, results suggested rapid acculturation of overweight-related behaviors, such as diet, smoking, and inactivity, in US-born relative to foreign-born immigrants. Multivariate analysis indicated that longer US residence was associated with increased overweight among Puerto Ricans and Cubans. Predicted probabilities showed that controlling for acculturation and proximate factors increased overweight among foreign-born adolescents, but had minimal impact for US-born adolescents. Thus, without the beneficial pattern of: acculturation factors, diet, and physical activity, first generation Hispanic adolescents would have higher overweight prevalence. We found important generation differences in structural, acculturation, and proximate overweight determinants. These lifestyle differences between foreign- and US-born Hispanic adolescent immigrants are likely to underlie the striking increase in overweight prevalence between first and subsequent generation of US residence.

Enjoyment mediates effects of a school-based physical-activity intervention.

PURPOSE The study evaluated whether targeted changes in factors influencing enjoyment of physical education (PE), physical activity enjoyment, and self-efficacy beliefs about participating in physical activity mediated the effect of the Lifestyle Education for Activity Program (LEAP) intervention on participation in physical activity. METHODS High schools (N=24) paired on enrollment size, racial composition, urban or rural location, and class structure were randomized into control (N=12) or experimental (N=12) groups. Of the 4044 girls enrolled and eligible, 2087 (51.6%) participated in the measurement component of the study. There were 1038 girls in the control group and 1049 girls in the experimental group. INTERVENTION LEAP was a comprehensive school-based intervention emphasizing changes in instruction and school environment designed to increase physical activity among black and white adolescent girls. It was organized according to the Coordinated School Health Program and included a PE component with core objectives of promoting enjoyment of PE, physical activity enjoyment, and self-efficacy. RESULTS Latent variable structural equation modeling indicated that: 1) the intervention had direct, positive effects on physical activity and factors influencing enjoyment of PE, which subsequently explained the effects of increased physical activity enjoyment and self-efficacy on increased physical activity; and 2) an additional, indirect effect of physical activity enjoyment on physical activity operated by an influence on self-efficacy. CONCLUSIONS Increases in enjoyment partially mediated the positive effect of the LEAP intervention. To our knowledge, we have provided the first experimental evidence from a randomized controlled trial linking increased enjoyment with increased physical activity among black and white adolescent girls.

Promotion of Physical Activity Among High-School Girls: A Randomized Controlled Trial

OBJECTIVES Many adolescent girls fail to meet national guidelines for physical activity, and the prevalence of obesity is increasing among this group. Our study examined the effects of a comprehensive school-based intervention on physical activity among high-school girls. METHODS A group-randomized controlled field trial was conducted at 24 high schools. A school-based sample of 2744 girls (48.7% African American, 46.7% White) participated in a measurement protocol when they were in eighth and then ninth grade. A comprehensive physical activity intervention was designed to change the instructional program and the school environment to increase support for physical activity among girls. RESULTS At follow-up, 45% of girls in the intervention schools and 36% of girls in the control schools reported vigorous physical activity during an average of 1 or more 30-minute time blocks per day over a 3-day period. CONCLUSIONS A comprehensive school-based intervention can increase regular participation in vigorous physical activity among high-school girls.

Physical Self-Concept and Self-Esteem Mediate Cross-Sectional Relations of Physical Activity and Sport Participation With Depression Symptoms Among Adolescent Girls

The authors tested whether physical self-concept and self-esteem would mediate cross-sectional relations of physical activity and sport participation with depression symptoms among 1,250 girls in 12th grade. There was a strong positive relation between global physical self-concept and self-esteem and a moderate inverse relation between self-esteem and depression symptoms. Physical activity and sport participation each had an indirect, positive relation with global physical self-concept that was independent of objective measures of cardiorespiratory fitness and body fatness. These correlational findings provide initial evidence suggesting that physical activity and sport participation might reduce depression risk among adolescent girls by unique, positive influences on physical self-concept that operate independently of fitness, body mass index, and perceptions of sports competence, body fat, and appearance.

Use of Text Messaging for Monitoring Sugar-sweetened Beverages, Physical Activity, and Screen Time in Children: A Pilot Study

OBJECTIVE To examine acceptability, attrition, adherence, and preliminary efficacy of mobile phone short message service (SMS; text messaging) for monitoring healthful behaviors in children. DESIGN All randomized children received a brief psychoeducational intervention. They then either monitored target behaviors via SMS with feedback or via paper diaries (PD) or participated in a no-monitoring control (C) for 8 weeks. SETTING University of North Carolina at Chapel Hill. PARTICIPANTS Fifty-eight children (age 5-13) and parents participated; 31 completed (SMS: 13/18, PD: 7/18, C: 11/22). INTERVENTION Children and parents participated in a total of 3 group education sessions (1 session weekly for 3 weeks) to encourage increasing physical activity and decreasing screen time and sugar-sweetened beverage consumption. MAIN OUTCOME MEASURES Treatment acceptability, attrition, and adherence to self-monitoring. ANALYSIS Descriptive statistics and nonparametric tests were used to analyze differences across time and group. RESULTS Children in SMS had somewhat lower attrition (28%) than both PD (61%) and C (50%), and significantly greater adherence to self-monitoring than PD (43% vs 19%, P < .02). CONCLUSIONS AND IMPLICATIONS Short message service may be a useful tool for self-monitoring healthful behaviors in children, although the efficacy of this approach needs further study. Implications suggest that novel technologies may play a role in improving health.

Examining Social-Cognitive Determinants of Intention and Physical Activity Among Black and White Adolescent Girls Using Structural Equation Modeling

Structural equation modeling was used to evaluate components within the theories of reasoned action (TRA), planned behavior (TPB), and self-efficacy (SET) for understanding moderate and vigorous physical activity among 1,797 Black and White adolescent girls. Modest to strong support was provided for components of TPB and SET; weak support was provided for components of TRA. Perceived behavioral control was related to vigorous physical activity. Self-efficacy was related to moderate and vigorous physical activity, and it accounted for the effect of intention on physical activity. The observed relationships were similar between Black and White girls. Self-efficacy and perceived behavioral control are independent influences on physical activity among Black and White adolescent girls and warrant study as potential mediators in physical activity interventions.

A systematic review of interventions for promoting active transportation to school.

BackgroundActive transportation to school is an important contributor to the total physical activity of children and adolescents. However, active school travel has declined over time, and interventions are needed to reverse this trend. The purpose of this paper is to review intervention studies related to active school transportation to guide future intervention research.MethodsA systematic review was conducted to identify intervention studies of active transportation to school published in the scientific literature through January 2010. Five electronic databases and a manual search were conducted. Detailed information was extracted, including a quantitative assessment comparing the effect sizes, and a qualitative assessment using an established evaluation tool.ResultsWe identified 14 interventions that focused on active transportation to school. These interventions mainly focused on primary school children in the United States, Australia, and the United Kingdom. Almost all the interventions used quasi-experimental designs (10/14), and most of the interventions reported a small effect size on active transportation (6/14).ConclusionMore research with higher quality study designs and measures should be conducted to further evaluate interventions and to determine the most successful strategies for increasing active transportation to school.

Interventions for Increasing Physical Activity at Child Care

Experts agree that physical activity is critical to childrens health and development. Child care is an ideal setting that could be used to increase physical activity given the large number of young children enrolled. To effectively address physical activity at child care, it is necessary to understand what strategies are most effective. This article reviews existing intervention studies targeting physical activity conducted within a child care setting (including preschools, nursery schools, and day care). Given the limited work in this setting, liberal criteria were used that allowed for inclusion of studies with diverse outcomes (physical activity, physical activity-related, motor skills) and a variety of research designs (randomized control, quasi-experimental, single group). Searching six databases, 1355 studies were located, and 19 met inclusion criteria. Half of the studies that assessed intervention impact on physical activity reported significant findings. All five studies measuring motor skills and eight assessing physical activity-related outcomes demonstrated generally positive findings. Although the variety of outcome measures and research quality made it difficult to draw conclusions, findings do provide encouragement that regularly provided, structured physical activity programs can increase the amount and intensity of physical activity that children receive and improve childrens motor skills. These studies also demonstrate that the organized child care setting provides multiple targets for intervention beyond structured activity programs; however, additional studies are needed to explore such opportunities.