Melody Oliver

Physical activity in preschoolers: understanding prevalence and measurement issues.

Accurate physical activity quantification in preschoolers is essential to establish physical activity prevalence, dose-response relationships between activity and health outcomes, and intervention effectiveness. To date, best practice approaches for physical activity measurement in preschool-aged children have been relatively understudied. This article provides a review of physical activity measurement tools for preschoolers, an overview of measurement of preschoolers’ physical activity, and directions for further research. Electronic and manual literature searches were used to identify 49 studies that measured young children’s physical activity, and 32 studies that assessed the validity and/or reliability of physical activity measures with preschool-aged children. While no prevalence data exist, measurement studies indicate that preschool children exhibit low levels of vigorous activity and high levels of inactivity, boys are more active than girls, and activity patterns tend to be sporadic and omnidirectional. As such, measures capable of capturing differing activity intensities in very short timeframes and over multiple planes are likely to have the most utility with this population. Accelerometers are well suited for this purpose, and a number of models have been used to objectively quantify preschoolers’ physical activity. Only one model of pedometer has been investigated for validity with preschool-aged children, showing equivocal results. Direct observation of physical activity can provide detailed contextual information on preschoolers’ physical activity, but is subjective and impractical for understanding daily physical activity. Proxy-report questionnaires are unlikely to be useful for determining actual physical activity levels of young children, and instead may be useful for identifying potential correlates of activity. Establishing validity is challenging due to the absence of a precise physical activity measure, or ‘criterion’, for young children. Both energy expenditure (EE) and direct observation have been considered criterion measures in the literature; however, EE is influenced by multiple variables, so its use as a physical activity ‘criterion’ is not ideal. Also, direct observation is inherently subjective, and coding protocols may result in failure to capture intermittent activity, thereby limiting its utility as a physical activity criterion. Accordingly, these issues must be taken into account where EE or direct observation are used to validate physical activity instruments. A combination of objective monitoring and direct observation may provide the best standard for the assessment of physical activity measurement tools. Ideally, the convergent validity of various physical activity tools should be investigated to determine the level of agreement between currently available measures. The correlational approaches commonly employed in the assessment of physical activity measures do not reveal this relationship, and can conceal potential bias of either measure.

Associations of children's independent mobility and active travel with physical activity, sedentary behaviour and weight status: A systematic review

UNLABELLED Health benefits from childrens independent mobility and active travel beyond school travel are largely unexplored. OBJECTIVES This review synthesized the evidence for associations of independent mobility and active travel to various destinations with physical activity, sedentary behaviour and weight status. DESIGN Systematic review. METHODS A systematic search in six databases (PubMed, Scopus, CINAHL, SportDiscus, PsychInfo, TRIS) for papers published between January 1990 and March 2012 was undertaken, focussing on children aged 3-18 years. Study inclusion and methodological quality were independently assessed by two reviewers. RESULTS 52 studies were included. Most studies focussed solely on active travel to and/or from school, and showed significant positive associations with physical activity. The same relationship was detected for active travel to leisure-related places and independent mobility with physical activity. An inverse relationship between active travel to school and weight status was evident but findings were inconsistent. Few studies examined correlations between active travel to school and self-reported screen-time or objectively measured sedentary behaviour, and findings were unclear. CONCLUSIONS Studies on independent mobility suggested that children who have the freedom to play outdoors and travel actively without adult supervision accumulate more physical activity than those who do not. Further investigation of childrens active travel to leisure-related destinations, measurement of diverse sedentary behaviour beyond simply screen-based activities, and consistent thresholds for objectively measured sedentary behaviour in children will clarify the inconsistent evidence base on associations of active travel with sedentary behaviour and weight status.

An Ethical Framework for Automated, Wearable Cameras in Health Behavior Research

Technologic advances mean automated, wearable cameras are now feasible for investigating health behaviors in a public health context. This paper attempts to identify and discuss the ethical implications of such research, in relation to existing guidelines for ethical research in traditional visual methodologies. Research using automated, wearable cameras can be very intrusive, generating unprecedented levels of image data, some of it potentially unflattering or unwanted. Participants and third parties they encounter may feel uncomfortable or that their privacy has been affected negatively. This paper attempts to formalize the protection of all according to best ethical principles through the development of an ethical framework. Respect for autonomy, through appropriate approaches to informed consent and adequate privacy and confidentiality controls, allows for ethical research, which has the potential to confer substantial benefits on the field of health behavior research.

Using the SenseCam to Improve Classifications of Sedentary Behavior in Free-Living Settings

BACKGROUND Studies have shown relationships between important health outcomes and sedentary behavior, independent of physical activity. There are known errors in tools employed to assess sedentary behavior. Studies of accelerometers have been limited to laboratory environments. PURPOSE To assess a broad range of sedentary behaviors in free-living adults using accelerometers and a Microsoft SenseCam that can provide an objective observation of sedentary behaviors through first person-view images. METHODS Participants were 40 university employees who wore a SenseCam and Actigraph accelerometer for 3-5 days. Images were coded for sitting and standing posture and 12 activity types. Data were merged and aggregated to a 60-second epoch. Accelerometer counts per minute (cpm) of <100 were compared with coded behaviors. Sensitivity and specificity analyses were performed. Data were collected in June and July 2011 and analyzed in April 2012. RESULTS TV viewing, other screen use, and administrative activities were correctly classified by the 100-cpm cutpoint. However, standing behaviors also fell under this threshold, and driving behaviors exceeded it. Multiple behaviors occurred simultaneously. A nearly 30-minute per day difference was found in sedentary behavior estimates based on the accelerometer versus the SenseCam. CONCLUSIONS Researchers should be aware of the strengths and weaknesses of the 100-cpm accelerometer cutpoint for identifying sedentary behavior. The SenseCam may be a useful tool in free-living conditions to better understand health behaviors such as sitting.

Effect of telephone counseling on physical activity for low-active older people in primary care: a randomized, controlled trial.

OBJECTIVES: To assess the long‐term effectiveness of a telephone counseling intervention on physical activity and health‐related quality of life in low‐active older adults recruited through their primary care physician.

Parent influences on preschoolers' objectively assessed physical activity

The purposes of this study were to examine the relationship between accelerometer-derived physical activity (PA) in preschoolers and their parents, and to investigate other potential child and parental associates of child PA. Families of children aged 2-5 yrs were recruited in Auckland, New Zealand, from October 2006 to July 2007. Consenting children and parents had their height, weight, and waist circumference measured and were asked to wear accelerometers over 7 consecutive days, measuring PA in 15s epochs. Accelerometer data were gathered from 78 children, 62 mothers and 20 fathers over a median of 6.5-7 days, and converted to estimated daily PA rates for each individual using negative binomial generalised estimating equation (GEE) modelling. Potential associates of childrens daily PA rates were then assessed using normal GEE models with exchangeable correlation structures. After taking account of all factors in the final multivariable model, parental PA rates (coefficient 0.09, 95% CI 0.03, 0.16, P=0.01) and child age (coefficient 0.11, 95% CI 0.01, 0.21, P=0.03) were the only factors significantly associated with child PA rates. Younger children may stand to benefit from PA intervention, and encouraging parental involvement in preschool PA interventions may be useful for increasing PA levels in young children. More work in this field is needed to corroborate these findings, improve generalisability, and determine causality.

Understanding the Relationship between Activity and Neighbourhoods (URBAN) Study: research design and methodology

BackgroundBuilt environment attributes are recognized as being important contributors to physical activity (PA) engagement and body size in adults and children. However, much of the existing research in this emergent public health field is hindered by methodological limitations, including: population and site homogeneity, reliance on self-report measures, aggregated measures of PA, and inadequate statistical modeling. As an integral component of multi-country collaborative research, the Understanding the Relationship between Activity and Neighbourhoods (URBAN) Study seeks to overcome these limitations by determining the strengths of association between detailed measures of the neighborhood built environment with PA levels across multiple domains and body size measures in adults and children. This article outlines the research protocol developed for the URBAN Study.Methods and designThe URBAN Study is a multi-centered, stratified, cross-sectional research design, collecting data across four New Zealand cities. Within each city, 12 neighborhoods were identified and selected for investigation based on higher or lower walkability and Māori demographic attributes. Neighborhoods were selected to ensure equal representation of these characteristics. Within each selected neighborhood, 42 households are being randomly selected and an adult and child (where possible) recruited into the study. Data collection includes: objective and self-reported PA engagement, neighborhood perceptions, demographics, and body size measures. The study was designed to recruit approximately 2,000 adults and 250 children into the project. Other aspects of the study include photovoice, which is a qualitative assessment of built environment features associated with PA engagement, an audit of the neighborhood streetscape environment, and an individualized neighborhood walkability profile centered on each participants residential address. Multilevel modeling will be used to examine the individual-level and neighborhood-level relationships with PA engagement and body size.DiscussionThe URBAN Study is applying a novel scientifically robust research design to provide urgently needed epidemiological information regarding the associations between the built environment and health outcomes. The findings will contribute to a larger, international initiative in which similar neighborhood selection and PA measurement procedures are utilized across eight countries. Accordingly, this study directly addresses the international priority issues of increasing PA engagement and decreasing obesity levels.

Utility of accelerometer thresholds for classifying sitting in office workers.

OBJECTIVE To investigate the utility of a variety of Actical accelerometer count thresholds for determining sitting time in a sample of office workers. METHODS Data were collected from 21 participants in Auckland, New Zealand, between December 2009 and January 2010. Participants wore a hip-mounted Actical accelerometer and thigh-mounted activPAL inclinometer (criterion) for a 48-h period. Raw inclinometer and accelerometer data for each 15s epoch of wear time were matched by date and time. Candidate accelerometer count thresholds for sitting classification were compared with the criterion measure using receiver operating characteristic analyses. Agreement in sitting time classification was determined using Bland-Altman methodology. RESULTS Significant differences in area under the curve (AUC) values by threshold criteria were found (p<0.001). A threshold of 0 counts provided the highest combined sensitivity and specificity (AUC 0.759, 95%CI 0.756, 0.761). The 95% limits of agreement for time spent sitting were wide, at 328min (range -30.8, 297.5). CONCLUSION A threshold of 0 counts/15s epoch with Actical accelerometers is likely to yield the most accurate quantification of sitting in office-based workers, however the wide limits of agreement found indicate limited utility of this threshold to accurately distinguish sitting time in office-based workers.

Portable global positioning system receivers: static validity and environmental conditions

BACKGROUND GPS receivers are becoming increasingly common as an objective measure of spatiotemporal movement in free-living populations; however, research into the effects of the surrounding physical environment on the accuracy of off-the-shelf GPS receivers is limited. PURPOSE The goal of the current study was to (1) determine the static validity of seven portable GPS receiver models under diverse environmental conditions and (2) compare the battery life and signal acquisition times among the models. METHODS Seven GPS models (three units of each) were placed on six geodetic sites subject to a variety of environmental conditions (e.g., open sky, high-rise buildings) on three separate occasions. The observed signal acquisition time and battery life of each unit were compared to advertised specifications. Data were collected and analyzed in June 2012. RESULTS Substantial variation in positional error was observed among the seven GPS models, ranging from 12.1 ± 19.6 m to 58.8 ± 393.2 m when averaged across the three test periods and six geodetic sites. Further, mean error varied considerably among sites: the lowest error occurred at the site under open sky (7.3 ± 27.7 m), with the highest error at the site situated between high-rise buildings (59.2 ± 99.2 m). While observed signal acquisition times were generally longer than advertised, the differences between observed and advertised battery life were less pronounced. CONCLUSIONS Results indicate that portable GPS receivers are able to accurately monitor static spatial location in unobstructed but not obstructed conditions. It also was observed that signal acquisition times were generally underestimated in advertised specifications.

Kids in the city study: research design and methodology

BackgroundPhysical activity is essential for optimal physical and psychological health but substantial declines in childrens activity levels have occurred in New Zealand and internationally. Childrens independent mobility (i.e., outdoor play and traveling to destinations unsupervised), an integral component of physical activity in childhood, has also declined radically in recent decades. Safety-conscious parenting practices, car reliance and auto-centric urban design have converged to produce children living increasingly sedentary lives. This research investigates how urban neighborhood environments can support or enable or restrict childrens independent mobility, thereby influencing physical activity accumulation and participation in daily life.Methods/DesignThe study is located in six Auckland, New Zealand neighborhoods, diverse in terms of urban design attributes, particularly residential density. Participants comprise 160 children aged 9-11 years and their parents/caregivers. Objective measures (global positioning systems, accelerometers, geographical information systems, observational audits) assessed childrens independent mobility and physical activity, neighborhood infrastructure, and streetscape attributes. Parent and child neighborhood perceptions and experiences were assessed using qualitative research methods.DiscussionThis study is one of the first internationally to examine the association of specific urban design attributes with child independent mobility. Using robust, appropriate, and best practice objective measures, this study provides robust epidemiological information regarding the relationships between the built environment and health outcomes for this population.