Sarah Burkart

• Doctor of Philosophy
• Assistant Professor at University of South Carolina

Background Summer vacation is a time when youth gain excessive weight. A key driver of unhealthy weight gain is poor dietary quality. The absence of consistent structure (e.g., school), is hypothesized to be one of the reasons for lower diet quality during summer. This study examined differences in school and summer dietary quality among a diverse...

Introduction This study examined the potential of a device agnostic approach for predicting physical activity energy expenditure (PAEE) from research grade and consumer wearable accelerometry and heartrate (HR) raw data compared to indirect calorimetry in children. Methods Two-hundred and thirty-one 5–12-year-olds (52.4% male) of diverse skin tone...

Background To examine the efficacy of providing free summer day camp (SDC) to children from low-income families on changes in physical activity, time spent sedentary, and screentime. Methods Across three summers (2021–2023), we randomized 422 children (8.2±1.5yrs, 48% female, 51% Black, 69% at or below 200% Federal Poverty Level, 30% food insecure...

Background Policy, systems, and environmental (PSE) approaches, including those enacted in early childhood education (ECE) settings, can improve child health outcomes. The use of implementation strategies, or the ways in which these approaches are enacted across settings, may modify intervention impact. Therefore, the purpose of this review was to...

Study Objectives Evaluate the performance of actigraphy-based open-source and proprietary sleep algorithms compared to polysomnography in children with suspected sleep disorders. Methods In a sleep clinic, 110 children (5-12 years, 54% female, 50% Black, 82% with sleep disorders) wore wrist-placed ActiGraph GT9X during overnight polysomnography. A...

Background The Structured Days Hypothesis posits that structure protects children against obesogenic behaviors (e.g., physical inactivity, unhealthy dietary intake) and, ultimately, prevents the occurrence of excessive weight gain. The hours following school (i.e., 3–6 pm school days) and summer vacation are two “windows of vulnerability” when chil...

Importance Children experience accelerated gains in body mass index (BMI) during the summer months when school is not in session. Children from low-income households are most susceptible. Accelerated BMI gain in summer may be due to the removal of the health-promoting structure provided by schools. During summer, a common form of health-promoting s...

Background: Physical activity, sedentary behavior, and sleep, collectively known as the 24-hour movement behaviors, demonstrate individual and joint benefits on physical and mental health. Examination of these behaviors has expanded beyond guideline adherence to reviews of isotemporal substitution models (ISM) and compositional data analysis (CoDA)...

Background Compositional data analysis (CoDA) techniques are well suited for examining associations between 24-h movement behaviors (i.e., sleep, sedentary behavior, physical activity) and indicators of health given they recognize these behaviors are co-dependent, representing relative parts that make up a whole day. Accordingly, CoDA techniques ha...

Background. The structured days hypothesis posits that structure protects children against obesogenic behaviors (e.g., physical inactivity, unhealthy dietary intake), and, ultimately, prevents the occurrence of excessive weight gain. The hours following school (i.e., 3-6pm school days) and summer vacation are two "windows of vulnerability" when chi...

Background Among elementary-aged children (5-12yrs), summer vacation is associated with accelerated gains in Body Mass Index (BMI). A key behavioral driver of BMI gain is a lack of physical activity (PA). Previous studies indicate PA decreases during summer, compared to the school year but whether this difference is consistent among boys and girls,...

Mobile devices (e.g., tablets and smartphones) have been rapidly integrated into the lives of children and have impacted how children engage with digital media. The portability of these devices allows for sporadic, on-demand interaction, reducing the accuracy of self-report estimates of mobile device use. Passive sensing applications objectively mo...

Study Objectives Evaluate wrist-placed accelerometry predicted heartrate compared to electrocardiogram (ECG) heartrate in children during sleep. Methods Children (n=82, 61% male, 43.9% Black) wore a wrist-placed Apple Watch Series 7 (AWS7) and ActiGraph GT9X during a polysomnogram. 3-Axis accelerometry data was extracted from AWS7 and the GT9X. Ac...

Background In the behavioral sciences, conducting pilot and/or feasibility studies (PFS) is a key step that provides essential information used to inform the design, conduct, and implementation of a larger-scale trial. There are more than 160 published guidelines, reporting checklists, frameworks, and recommendations related to PFS. All of these pu...

Background : Twenty-four hour movement behaviors (ie, physical activity [PA], screen time [ST], and sleep) are associated with children’s health outcomes. Identifying day-level contextual factors, such as child care, that positively influence children’s movement behaviors may help identify potential intervention targets, like improving access to ch...

The purpose of this study was to evaluate the reliability and validity of the raw accelerometry output from research-grade and consumer wearable devices compared to accelerations produced by a mechanical shaker table. Raw accelerometry data from a total of 40 devices (i.e., n = 10 ActiGraph wGT3X-BT, n = 10 Apple Watch Series 7, n = 10 Garmin Vivoa...

Preliminary studies play a prominent role in the development of large-scale behavioral interventions. Though recommendations exist to guide the execution and interpretation of preliminary studies, these assume optimal scenarios which may clash with realities faced by researchers. The purpose of this study was to explore how principal investigators...

Background Objective measures of screen time are necessary to better understand the complex relationship between screen time and health outcomes. However, current objective measures of screen time (e.g., passive sensing applications) are limited in identifying the user of the mobile device, a critical limitation in children’s screen time research w...

Background Preliminary studies (e.g., pilot/feasibility studies) can result in misleading evidence that an intervention is ready to be evaluated in a large-scale trial when it is not. Risk of Generalizability Biases (RGBs, a set of external validity biases) represent study features that influence estimates of effectiveness, often inflating estimate...

Background: Despite the widespread endorsement of 24-h movement guidelines (physical activity, sleep, screen-time) for youth, no standardized processes for categorizing guideline achievement exists. The purpose of this study was to illustrate the impact of different data handling strategies on the proportion of children meeting 24-h movement guidel...

The purpose of this meta-analysis was to quantify the difference in physical activity and sleep estimates assessed via 1) movement, 2) heart rate (HR), or 3) the combination of movement and HR (MOVE+HR) compared to criterion indicators of the outcomes. Searches in four electronic databases were executed September 21–24 of 2021. Weighted mean was ca...

Background : Two-thirds of children in the United States do not meet the National Physical Activity Guidelines, leaving a majority at higher risk for negative health outcomes. Novel, effective children’s physical activity (PA) interventions are urgently needed. Dog-facilitated PA (e.g., dog walking and active play) is a promising intervention targe...

We examined the comparability of children's nocturnal sleep estimates using accelerometry data, processed with and without a sleep log. In a secondary analysis, we evaluated factors associated with disagreement between processing approaches. Children (n = 722, age 5–12 years) wore a wrist‐based accelerometer for 14 days during Autumn 2020, Spring 2...

Background: Despite the widespread endorsement of 24-hour movement guidelines (physical activity, sleep, screentime) for youth, no standardized processes for categorizing guideline achievement exists. Different data handling procedures prior to classification (averaging movement behavior across multiple days, categorizing the number days guidelines...

Background In the behavioral sciences, conducting pilot and/or feasibility studies (PFS) is a key step that provides essential information used to inform the design, conduct, and implementation of a larger-scale trial. There are more than 160 published guidelines, reporting checklists, frameworks, and recommendations related to PFS. All of these pu...

Background Guidelines, checklists, frameworks, and recommendations (GCFRs) related to preliminary studies serve as essential resources to assist behavioral intervention researchers in reporting findings from preliminary studies, but their impact on preliminary study reporting comprehensiveness is unknown. The purpose of this study was to conduct a...

Introduction This study examined the potential of a device agnostic approach for predicting physical activity from consumer wearable accelerometry compared to a research-grade accelerometry. Methods Seventy-five 5–12-year-olds (58% male, 63% White) participated in a 60-minute protocol. Children wore wrist-placed consumer wearables (Apple Watch Ser...

Background The number of preliminary studies conducted and published has increased in recent years. However, there are likely many preliminary studies that go unpublished because preliminary studies are typically small and may not be perceived as methodologically rigorous. The extent of publication bias within preliminary studies is unknown but can...

Policy, systems, and environmental (PSE) approaches can facilitate physical activity in priority populations (e.g., racial and ethnic minority, low wealth groups) within early childhood education (ECE) settings. The purpose of this review was to 1) characterize the inclusion of priority populations within ECE physical activity interventions contain...

Goal and aims: Evaluate the performance of a sleep scoring algorithm applied to raw accelerometry data collected from research-grade and consumer wearable actigraphy devices against polysomnography. Focus method/technology: Automatic sleep/wake classification using the Sadeh algorithm applied to raw accelerometry data from ActiGraph GT9X Link, A...

The purpose of this study was to evaluate the reliability and validity of the raw accelerometry output from research-grade and consumer wearable devices compared to accelerations produced by a mechanical shaker table. Raw accelerometry data from a total of 40 devices (i.e., n=10 ActiGraph wGT3X-BT, n=10 Apple Watch Series 7, n=10 Garmin Vivoactive...

Objectives: Preliminary studies play a key role in developing large-scale interventions but may be held to higher or lower scientific standards during the peer review process because of their preliminary study status. Study design: Abstracts from five published obesity prevention preliminary studies were systematically modified to generate 16 va...

Background: Drivers of summer body mass index (BMI) gain in children remain unclear. The Circadian and Circannual Rhythm Model (CCRM) posits summer BMI gain is biologically driven, while the Structured Days Hypothesis (SDH) proposes it is driven by reduced structure. Objectives: Identify the mechanisms driving children's seasonal BMI gain through t...

Photoplethysmography (PPG) signal quality as a proxy for accuracy in heart rate (HR) measurement is useful in various public health contexts, ranging from short-term clinical diagnostics to free-living health behavior surveillance studies that inform public health policy. Each context has a different tolerance for acceptable signal quality, and it...

Background Behavioral interventions are often complex, operate at multiple levels, across settings, and employ a range of behavior change techniques. Collecting and reporting key indicators of initial trial and intervention feasibility is essential to decisions for progressing to larger-scale trials. The extent of reporting on feasibility indicator...

Early childhood education (ECE) settings play an important role in child dietary intake and excess weight gain. Policy, systems, and environment (PSE) approaches have potential to reduce disparities in children at higher risk for obesity. The purpose of this review was to (1) characterize the inclusion of populations at higher risk for obesity in E...

This study gathered formative data on barriers to optimal child sleep to inform the development of a sleep intervention for parents of preschool-aged children in low-income households. Parents (n = 15, age: 34 ± 8 years, household income: $30,000 ± 17,845/year) reporting difficulties with their child’s sleep participated in this study. Mixed method...

Children from low-income households, and who are overweight or obese (OWOB), are at risk of accelerated weight gain during summer. Summer day camps (SDCs) have the potential to mitigate accelerated weight gain during summer as these settings can positively influence children's obesogenic behaviors (i.e., increase physical activity); however, barrie...

Background: It is essential to quantify the accuracy and precision of bioelectrical impedance (BIA)-estimated percent body fat (%BF) to better interpret community-based research findings that utilize opportunistic measures. Methods: Study 1 measured the accuracy of a new dual-frequency foot-to-foot BIA device (Tanita DC-430U) compared with dual-ene...

Innovative, groundbreaking science relies upon preliminary studies (aka pilot, feasibility, proof-of-concept). In the behavioral sciences, almost every large-scale intervention is supported by a series of one or more rigorously conducted preliminary studies. The importance of preliminary studies was established by the National Institutes of Health...

Background: Adequate sleep is essential for various health outcomes (e.g., obesity, diabetes, and cardiovascular disease). However, sleep time is threatened by the increased opportunities for unsupervised screen time available to children of all ages. The American Academy of Sleep Medicine recommends that elementary-aged children sleep between 9-12...

The pandemic mitigation strategy of closing schools, while necessary, may have unintentionally impacted children’s moderate-to-vigorous physical activity (MVPA), sleep, and time spent watching screens. In some locations, schools used hybrid attendance models, with some days during the week requiring in-person and others virtual attendance. This sce...

Movement integration (MI) products are one of many MI strategies that aim to reduce students’ sedentary behavior (SB) and increase physical activity (PA) during classroom time. This study examined elementary classroom teachers’ off-the-shelf (i.e., no researcher support) use of MI products (GoNoodle Plus [GN], ABC for Fitness [ABC], Take10) and the...

Background Guidelines, checklists, frameworks, and recommendations (GCFRs) related to preliminary studies serve as essential resources to assist behavioral intervention researchers in reporting findings from preliminary studies, but their impact on preliminary study quality is unknown. The purpose of this study was to conduct a scoping bibliometric...

BACKGROUND Digital media technology has made screen time more available across multiple contexts, but our understanding of the unique ways children and families use digital media has lagged behind the rapid adoption of this technology. OBJECTIVE The purpose of this study was to evaluate the feasibility of an intensive longitudinal data collection...

Background Digital media has made screen time more available across multiple contexts, but our understanding of the ways children and families use digital media has lagged behind the rapid adoption of this technology. Objective This study evaluated the feasibility of an intensive longitudinal data collection protocol to objectively measure digital...

Introduction Variability in children’s sleep patterns has been linked with health outcomes including obesity, poor mood, and behavioral difficulties. However, much of this evidence stems from parent-reported measures of sleep. Understanding these associations in preschool-age children using device-based measures is important as sleep habits tend to...

Background: Behavioral interventions are often complex, operate at multiple levels, across settings, and employ a range of behavior change techniques. Collecting and reporting key indicators of initial trial and intervention feasibility is essential to decisions for progressing to larger-scale trials. The extent of reporting on feasibility indicato...

Background Pilot/feasibility studies play an important role in the development and refinement of behavioral interventions by providing information about feasibility, acceptability, and potential efficacy. Despite their importance and wide-spread use, the approaches taken by behavioral scientists to scale-up early-stage studies to larger-scale trial...

Background: Excessive screen time is associated with poor health and behavioral outcomes in children. However, research on screen time use has been hindered by methodological limitations, including retrospective reports of usual screen time and lack of momentary etiologic processes occurring within each day. Objective: This study is designed to...

Background Careful consideration and planning are required to establish “sufficient” evidence to ensure an investment in a larger, more well-powered behavioral intervention trial is worthwhile. In the behavioral sciences, this process typically occurs where smaller-scale studies inform larger-scale trials. Believing that one can do the same things...

Despite childcare providers’ substantial interaction with toddlers, very little is known about providers’ perception of toddlers’ physical activity (PA) and how to facilitate toddler PA. This qualitative study examines facilitators, barriers, and components of a PA intervention to improve toddlers’ PA within the childcare setting. Providers from th...

Biases introduced in early-stage studies can lead to inflated early discoveries. The risk of generalizability biases (RGBs) identifies key features of feasibility studies that, when present, lead to reduced impact in a larger trial. This meta-study examined the influence of RGBs in adult obesity interventions. Behavioral interventions with a publis...

Background COVID‐19 school closures pose a threat to children's wellbeing, but no COVID‐19‐related studies have assessed children's behaviours over multiple years . Objective To examine children's obesogenic behaviours during spring and summer of the COVID‐19 pandemic compared to previous data collected from the same children during the same calen...

Background: Early childhood is an important age for brain and cognitive development. Given the support of physical activity and fitness on cognition and academic performance in older children, more research has emerged recently focusing on younger children. In this systematic review, the authors review the relations between physical activity/fitne...

Objective Children who fail to meet activity, sleep, and screen‐time guidelines are at increased risk for obesity. Further, children who are Black are more likely to have obesity when compared to children who are White, and children from low‐income households are at increased risk for obesity when compared to children from higher‐income households....

Background: Pilot/feasibility studies play an important role in the development and refinement of behavioral interventions by providing information about feasibility, acceptability, and potential efficacy. Despite their importance and wide-spread use, the approaches taken by behavioral scientists to scale-up early-stage studies to larger-scale tria...

Introduction In spring 2020, elementary schools closed to minimize the spread of COVID-19. Questionnaire data suggest children’s sleep was impacted during the pandemic, yet device-based data (i.e. accelerometry) on this topic is lacking. The purpose of this study was to examine children’s sleep during the COVID-19 pandemic (i.e. spring and summer 2...

Introduction The coronavirus disease 2019 (COVID-19) pandemic may have negatively impacted children's weight status owing to the closure of schools, increased food insecurity and reliance on ultra-processed foods, and reduced opportunities for outdoor activity. Methods In this interrupted time series study, height and weight were collected from ch...

Study objectives: To compare sleep parameters produced by the Fitbit Charge 3 (Fitbit) and Actigraph GT9X accelerometer (Actigraph) to polysomnography (PSG) in youth. Methods: Youth (n=56, age=9.2±3.3 years) wore a Fitbit and Actigraph on their non-dominant wrist concurrently with PSG during an overnight observation at a children's sleep lab. To...

Although some studies indicate physical activity and sleep quality are positively associated in children, most reports examined physical activity independent of other 24-h behaviors and focused on older children. The aim of this cross-sectional study was to examine the predicted changes in sleep efficiency and habits when reallocating time between...

Aims To assess the impact of a culturally modified, motivationally targeted, individually-tailored intervention on postpartum physical activity (PA) and PA self-efficacy among Hispanic women. Methods Estudio PARTO was a randomized controlled trial conducted in Western Massachusetts from 2013–17. Hispanic women who screened positive for gestational...

Heart rate (HR), when combined with accelerometry, can dramatically improve estimates of energy expenditure and sleep. Advancements in technology, via the development and introduction of small, low-cost photoplethysmography devices embedded within wrist-worn consumer wearables, have made the collection of heart rate (HR) under free-living condition...

Although fitness may benefit cognition in youth, most attention has been given to cardiorespiratory fitness despite the health benefits of muscular fitness. Few studies have examined interventions that incorporate both cardiorespiratory and muscular fitness or have been offered during school recess. Furthermore, most fitness intervention studies ex...

Background: For a health behavior intervention to be sustainable within preschool centers, the intervention should be implemented by classroom teachers. Unfortunately, teachers are constrained by demands such as meeting early childhood education standards. Therefore, the purpose of this pilot study was to examine the feasibility and preliminary ef...

The purpose of this review was to assess the effectiveness of physical activity (PA) interventions in African American and Latino/ Hispanic preschool children. A systematic search was conducted for English-language printed research articles published between January 1980 and December 2017. The inclusion criteria for studies in this review were that...

Positive parent-child attachment can be determined by opportunities for the child to interact with his/her parent and can influence a child's physical activity (PA) behavior. Therefore, an intervention that provides children and their parent more time to interact positively could impact children's PA. We examined the efficacy of a 12-week mother-da...

Background: Poor adaptive learning behaviors (i.e. distractibility, inattention, disruption) are associated with behavior problems and underachievement in school, as well as indicating potential attention deficit hyperactivity disorder (ADHD). Strategies are needed to limit these behaviors. Physical activity (PA) has been suggested to improve beha...

The purpose of this study was to describe process evaluation data including intervention fidelity, dosage, quality, participant responsiveness, and program reach for the Mothers And dauGhters daNcing togEther Trial (MAGNET) in Springfield, MA, in Spring 2013 and 2014. Seventy-six mother-daughter dyads were randomized to the mother-daughter group (C...

Background: Thirty-five percent of the activities assigned MET values in the Compendium of Energy Expenditures for Youth were obtained from direct measurement of energy expenditure (EE). The aim of this study was to provide directly measured EE for several different activities in youth. Methods: Resting metabolic rate (RMR) of 178 youths (80 fem...

Maternal influence has been reported to play a significant role in the health behaviors of children. In Caucasian girls, it has been reported that mother-daughter relationship can influence psychosocial variables such as physical activity (PA) self-efficacy. Currently, there is very little data on the impact of African-American girls’ perception of...