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.

The objective of this study was to determine if moderate to vigorous physical activity (MVPA) of 3-5 year old preschool children varied with differences in policies/practices, and overall quality of preschools. A total of 266 children (47% males, 60% African American) from 9 preschools were observed for 1 hour on 3 different days. PA of children was observed twice per minute and scored as 1-5, with 1 for stationary/motionless and 5 for fast movement. Summary MVPA was calculated over the 3 days as percent of times observed at levels of 4 or 5, and percent of time at levels 1 or 2 as sedentary activity. A structured interview about PA policies was conducted with an administrator at each preschool and overall quality of the preschool was assessed using Early Childhood Environment Rating Scale-Revised Edition (ECERS-R). Preschools were divided into groups according to whether a specific policy/practice that would be logically hypothesized to promote PA was in place at the school. MVPA differences between groups of children was assessed using mixed ANOVA controlling for preschool. When preschools offered more field trips, and more college educated teachers, the children participated in more MVPA. Children who attended preschools with lower quality spent more time in sedentary activity. In conclusion, children in preschools which may have more resources and better quality appear to show both more sedentary behavior and more MVPA.

The Actical accelerometer is a valid tool for measuring PA in young children.

Numerous studies have examined the association between the surrounding neighborhood environment and physical activity levels in adolescents. Many of these studies use a road network buffer or Euclidean distance buffer around an adolescent's home to represent the appropriate geographic area for study (i.e., neighborhood). However, little empirical research has examined the appropriate buffer size to use when defining this area and there is little consistency across published research as to the buffer size used. In this study, 909 12 th grade adolescent girls of diverse racial and geographic backgrounds were asked to report their perceptions of an easy walking distance and a convenient driving distance. These two criterions are often used as the basis for defining one's neighborhood.The mean easy walking distance in minutes reported by adolescent girls was 14.8 minutes (SD = 8.7). The mean convenient driving distance in minutes reported was 17.9 minutes (SD = 10.8). Nested linear multivariate regression models found significant differences in reported 'easy walking distance' across race and BMI. White adolescents reported on average almost 2 minutes longer for an easy walking distance compared to African American adolescents. Adolescents who were not overweight or at risk for overweight reported almost 2 minutes fewer for an easy walking distance relative to those who were overweight or at risk for overweight. Significant differences by urban status were found in the reported 'convenient driving distance'. Those living in non-urban areas reported on average 3.2 minutes more driving time as convenient compared to those living in urban areas. Very little variability in reported walking and driving distances was explained by the predictors used in the models (i.e., age, race, BMI, physical activity levels, urban status and SES).This study suggests the use of a 0.75 mile buffer to represent an older female adolescent's neighborhood, which can be accessed through walking. However, determining the appropriate area inclusive of car travel should be tailored to the geographic location of the adolescent since non-urban adolescents are willing to spend more time driving to destinations. Further research is needed to understand the substantial variability across adolescent perceptions of an easy walking and convenient driving distance.

Background-Physical activity behavior is influenced by a person's physical environment, but few studies have used objective measures to study the influences of the physical environment on physical activity behavior in youth. The purpose of this study was to examine the relationship between selected neighborhood physical activity resources and physical activity levels in high school girls.

In this paper we present initial information concerning a new direct observation system-the Observational System for Recording Physical Activity in Children-Preschool Version. The system will allow researchers to record young children's physical activity levels while also coding the topography of their physical activity, as well as detailed indoor and outdoor social and nonsocial contextual information. With respect to interobserver agreement (IOA), the kappa and category-by-category agreement mean of those obtained for the three illustrative preschools were generally above .80. Hence, our IOA data indicated that trained observers in the three preschools frequently agreed on the eight observational categories and accompanying codes. The results for preschoolers' level of physical activity indicated they spent the majority of observational intervals in sedentary activity (i.e., more than 80% intervals) and were observed in moderate to vigorous physical activity much less frequently (i.e., 5% or fewer intervals). For the 15 indoor and 12 outdoor activity contexts, variability across both the activity contexts and the three preschools were evident. Nevertheless, three classroom contexts-transition, snacks, and naptime--accounted for the greatest porportion of coded activity contexts for the children. In the three preschools, 4 of 17 physical activity types--sit and squat, lie down, stand, and walk--accounted for the topography of much of children's physical activity behavior Systematic observation of more representative preschool samples might better inform our present understanding of young children's physical activity in community preschool programs.

Objective-The purposes of this study were to describe the types and availability of commercial facilities for physical activity (PA) in six diverse geographic areas (Washington DC and Maryland; South Carolina; Minnesota; Louisiana; Arizona; and California) and to assess the relationship between those facilities and the non-school PA of adolescent girls.Methods-A total of 1556 6th grade girls participating in the Trial of Activity for Adolescent Girls (TAAG) wore accelerometers for 7 days providing 6 days of complete data, completed questionnaires in 2003 and had their residential addresses geocoded. Nearby commercial facilities available to provide PA (i.e. dance studios, youth organizations) within a 1-mile radius of participants' residences were identified and geocoded. The association between the presence of any commercial PA facility and girls' PA was determined using a multi-level design and controlling for demographic characteristics and other potential confounders. Analyses were conducted in 2005-2006. Results-Sixty-eight percent of the girls had at least one commercial PA facility near their homes. Availability and types of commercial PA facilities differed by where participants lived. Girls who lived near one or more commercial PA facilities had higher non-school MET-weighted moderateto-vigorous PA than girls who had none near their homes.Conclusions-The findings suggest that commercial PA facilities are important contributors to the accumulation of PA among adolescent girls.

OBJECTIVEThe purpose of this study was to examine independent and joint associations of cardiorespiratory fitness (CRF) and different adiposity measures with mortality risk in individuals with prediabetes (or impaired fasting glucose).RESEARCH DESIGN AND METHODSWe examined associations of CRF and fatness with cardiovascular disease (CVD) and all-cause mortality in a cohort of 17,044 participants (89% men) with prediabetes (defined as 100 mg/dL ≤ fasting plasma glucose < 126 mg/dL), who did not have a history of diabetes, CVD, or cancer.RESULTSWe identified 832 deaths (246 from CVD) during 13.9 ± 7.0 years (mean ± SD) follow-up. Normal-weight individuals who were unfit (lowest one-third) had a higher risk of all-cause (hazard ratio 1.70 [95% CI 1.32–2.18]) and CVD (1.88 [1.13–3.10]) mortality compared with the normal-weight and fit (upper two-thirds) reference group in a model adjusted for age, sex, examination year, and multiple risk factors. The mortality risk for fit individuals who were overweight or obese did not differ significantly from the reference group. Similar patterns were observed for sex-specific thirds of waist circumference and % body fat.CONCLUSIONSCRF markedly modifies the relationship between adiposity and mortality in persons with prediabetes. Unfit individuals have a higher and fit individuals have a lower mortality risk irrespective of adiposity level in this high-risk group.