PATE, RUSSELL R., MARIA J. ALMEIDA, KERRY L. MCIVER, KARIN A. PFEIFFER, AND MARSHA DOWDA. Validation and calibration of an accelerometer in preschool children. Obesity. 2006;14:2000-2006. Objective: Obesity rates in young children are increasing, and decreased physical activity is likely to be a major contributor to this trend. Studies of physical activity in young children are limited by the lack of valid and acceptable measures. The purpose of this study was to calibrate and validate the ActiGraph accelerometer for use with 3-to 5-year-old children. Research Methods and Procedures:Thirty preschool children wore an ActiGraph accelerometer (ActiGraph, Fort Walton Beach, FL) and a Cosmed portable metabolic system (Cosmed, Rome, Italy) during a period of rest and while performing three structured physical activities in a laboratory setting. Expired respiratory gases were collected, and oxygen consumption was measured on a breath-by-breath basis. Accelerometer data were collected at 15-second intervals. For cross-validation, the same children wore the same instruments while participating in unstructured indoor and outdoor activities for 20 minutes each at their preschool. Results: In calibrating the accelerometer, the correlation between V O 2 (ml/kg per min) and counts was r ϭ 0.82 across all activities. The only significant variable in the prediction equation was accelerometer counts (R 2 ϭ 0.90, standard error of the estimate ϭ 4.70). In the cross-validation, the intraclass correlation coefficient between measured and predicted V O 2 was R ϭ 0.57 and the Spearman correlation coefficient was R ϭ 0.66 (p Ͻ 0.001). Cut-off points for moderate-and vigorous-intensity physical activity were identified at 420 counts/15 s (V O 2 ϭ 20 mL/kg per min) and 842 counts/15 s (V O 2 ϭ 30 mL/kg per min), respectively. When these cutpoints were applied to the cross-validation data, percentage agreement, kappa, and modified kappa for moderate activity were 0.69, 0.36, and 0.38, respectively. For vigorous activity, the same measures were 0.81, 0.13, and 0.62. Discussion: Accelerometer counts were highly correlated with V O 2 in young children. Accelerometers can be appropriately used as a measure of physical activity in this population.

Children with better-developed motor skills may find it easier to be active and engage in more physical activity (PA) than those with less-developed motor skills. The purpose of this study was to examine the relationship between motor skill performance and PA in preschool children. Participants were 80 three-and 118 four-year-old children. The Children's Activity and Movement in Preschool Study (CHAMPS) Motor Skill Protocol was used to assess process characteristics of six locomotor and six object control skills; scores were categorized as locomotor, object control, and total. The actigraph accelerometer was used to measure PA; data were expressed as percent of time spent in sedentary, light, moderate-to-vigorous PA (MVPA), and vigorous PA (VPA). Children in the highest tertile for total score spent significantly more time in MVPA (13.4% vs. 12.8% vs. 11.4%) and VPA (5% vs. 4.6% vs. 3.8%) than children in middle and lowest tertiles. Children in the highest tertile of locomotor scores spent significantly less time in sedentary activity than children in other tertiles and significantly more time in MVPA (13.4% vs. 11.6%) and VPA (4.9% vs. 3.8%) than children in the lowest tertile. There were no differences among tertiles for object control scores. Children with poorer motor skill performance were less active than children with better-developed motor skills. This relationship between motor skill performance and PA could be important to the health of children, particularly in obesity prevention. Clinicians should work with parents to monitor motor skills and to encourage children to engage in activities that promote motor skill performance.

Children's physical activity levels were highly variable among preschools, which suggests that preschool policies and practices have an important influence on the overall activity levels of the children the preschools serve.

The two-fold purpose of the investigation was (1) to describe with direct observation data the physical activity behaviors and the accompanying social and environmental events of those behaviors for children in preschools; and (2) to determine which contextual conditions were predictors of moderateto-vigorous physical activity (MVPA) and non-sedentary physical activity (i.e., light activity + MVPA) for 3-, 4-, and 5-year-old children during their outdoor play. The results indicate that preschoolers' physical activity is characterized as sedentary in nature throughout their preschool day (i.e., 89% sedentary, 8% light activity, 3% MVPA). During outdoor play periods, when children are most likely to be physically active, some contextual and social circumstances better predict their physical activity. Implications for policymakers, practitioners, and researchers are discussed.Keywords preschool children; physical activity; physical inactivity; childhood overweight and obesity; direct observation methods Recently, the childhood obesity rate has increased considerably in the United States, and many children are becoming overweight at younger ages. Ogden and colleagues (2006) reported that the prevalence rate of at risk for overweight (i.e., ≥ 85 th percentile) among two-to five-yearold children in the U. S. was 26.2% and during the last five years the rate increased by 4.2%. Within the United States, some populations, such as African American, Hispanic, and lowincome children, have had even higher prevalence rates for childhood weight difficulties (e.g., Haas et al., 2003;Sherry, Mei, Scanlon, Mokdad, & Grummer-Strawn, 2004 NIH Public Access Author ManuscriptChild Dev. Author manuscript; available in PMC 2010 January 1. Published in final edited form as:Child Dev. 2009 ; 80(1): 45-58. doi:10.1111/j.1467-8624.2008.01245.x. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptSirard, Dowda, Pfeiffer, and Pate (2003) noted that early incidence of being overweight might inhibit young children's physical activity, negatively affecting their future weight status. Finally, Guo, Wu, Chumlea, and Roche (2002) and Baker, Olsen, and Sorensen (2007) reported children's early overweight problems predict adult obesity and significant health problems.The causal nexus between obesity and severe health problems is multifaceted and any connection may be confounded by the fact that both health problems and obesity have been associated with poor diet and lack of exercise. Nevertheless, obesity has been clearly associated with multiple health difficulties, most notably, coronary heart disease, hypertension, type II diabetes, osteoporosis, and some types of cancer (e.g., Blair & Brodney, 1999;Must et al., 1999). Many public health researchers have hypothesized that obesity is related to contemporary diets and physical inactivity (e.g., Biglan, 2004;Troiano & Flegal, 1998). Specifically, modern diets have increased caloric intake, particularly calories with saturated and trans fats and sugars, and the physical...

Background:The purposes of this study were 1) to establish accelerometer count cutoffs to categorize activity intensity of 3 to 5-y old-children and 2) to evaluate the accelerometer as a measure of children's physical activity in preschool settings. Methods: While wearing an ActiGraph accelerometer, 16 preschool children performed five, 3-min structured activities. Receiver Operating Characteristic (ROC) curve analyses identified count cutoffs for four physical activity intensities. In 9 preschools, 281 children wore an ActiGraph during observations performed by three trained observers (interobserver reliability = 0.91 to 0.98). Results: Separate count cutoffs for 3, 4, and 5-y olds were established. Sensitivity and specificity for the count cutoffs ranged from 86.7% to 100.0% and 66.7% to 100.0%, respectively. ActiGraph counts/15 s were different among all activities (P < 0.05) except the two sitting activities. Correlations between observed and ActiGraph intensity categorizations at the preschools ranged from 0.46 to 0.70 (P < 0.001). Conclusions: The ActiGraph count cutoffs established and validated in this study can be used to objectively categorize the time that preschool-age children spend in different physical activity intensity levels.