Virginie Nicaise

Correlates of moderate-to-vigorous physical activity among preschoolers during unstructured outdoor play periods

OBJECTIVE Quantify moderate-to-vigorous physical activity (MVPA) and its correlates in preschool children during outdoor unstructured play periods using direct observation. METHODS Cross-sectional data consisting of 204 observation periods collected from 51 four- and five-year-old children using the Observation System for Recording Physical Activity in Children - Preschool (OSRAC-P) at a preschool in southern California, autumn and spring 2009-2010. Gender and BMI classification and OSRAC-P environmental codes were related to observed MVPA in multiple logistic regression models. RESULTS Less than 21% of intervals were spent in MVPA overall. Boys and normal weight children engaged in higher intensity levels than their respective counterparts. More MVPA was associated with normal weight (OR=2.49-3.25, R(2)=3%), location (grass, playground, looping cycle path; OR=3.21-4.90, R(2)=4-12%), play context (ball/objects, wheel, open space; OR=2.78-8.51, R(2)=9%), and group composition (solitary, one-on-one; OR=1.34-2.08, R(2)=1%). CONCLUSION Open spaces located in playgrounds and grass fields, and activity-genic portable equipment, manipulative objects, and riding vehicles are some design and equipment features that appear to foster MVPA. Lowering play space density and engaging children through teacher prompts and teacher-arranged activities may further increase MVPA on playgrounds.

Using step cadence goals to increase moderate-to-vigorous-intensity physical activity.

BACKGROUND Increasing moderate-to-vigorous-intensity physical activity (MVPA) is an important public health goal. Pedometers are evidence-based devices for increasing daily activity, but studies have not evaluated the comparative efficacy of step cadence goals for increasing MVPA. PURPOSE This study aimed to evaluate the efficacy of three pedometer-based step goals for increasing MVPA. METHODS Latina women (n = 180; 18-55 yr, mean body mass index = 31.1, SD = 6.5) were recruited to 12 community centers, which were randomly assigned to one of three conditions. Each group received an identical 12-wk theory-based physical activity (PA) intervention that differed only on the type of daily step goal: 1) a self-selected goal (SELF); 2) a goal of 10,000 steps per day (FREQUENCY); or 3) a goal of 3000 steps in 30 min (CADENCE). Accelerometer-based PA was measured at baseline and after 12 wk. RESULTS Adjusted multilevel pattern-mixture models using generalized estimating equations revealed that participants in the CADENCE condition engaged in similar levels of postintervention MVPA to those in the SELF and FREQUENCY goal conditions. However, MVPA of participants in the CADENCE condition was more likely to occur in bouts lasting greater than 10 consecutive minutes compared with the MVPA of participants in the SELF (P = 0.01) or FREQUENCY (P = 0001) conditions. CONCLUSIONS PA interventions should consider including a step cadence goal to help individuals accumulate bout-based MVPA and meet national PA guidelines.

Convergent Validity of Four Accelerometer Cutpoints With Direct Observation of Preschool Children's Outdoor Physical Activity

Purpose: More than one fifth of American preschool-aged children are classified as overweight/obese. Increasing physical activity is one means of slowing/reversing progression to overweight or obesity. Measurement of physical activity in this age group relies heavily on motion sensors such as accelerometers. Output is typically interpreted through application of one of several cutpoints to quantify the amount of time spent at various physical activity levels. Cutpoint nonequivalence has resulted in widely varying estimates of physical activity. Thus, we sought to ascertain the convergent validity of four ActiGraph accelerometer cutpoints with the Observation System for Recording Activity in Children–Preschool (OSRAC–P). Method: Two studies were conducted with sixty-nine 4- and 5-year-olds during unstructured outdoor free play at a single university campus preschool in Southern California. In Study 1 (N = 57), percentages of time spent in sedentary behavior (SED) and moderate-to-vigorous physical activity (MVPA) were compared at the aggregate level using the two-proportion z-test and Bland Altman plots. In Study 2 (N = 12), time-matched 5-s intervals between accelerometery and the OSRAC–P were compared using percent agreement, kappa, and classification functions. Results: In Study 1, cutpoints by Sirard, Trost, Pfeiffer, Dowda, and Pate (2005) best converged with the OSRAC–P estimates of SED and MVPA. In Study 2, Sirard et al. cutpoints and those by Pate, Almeida, McIver, Pfeiffer, and Dowda (2006) were more sensitive in detecting SED and MVPA, respectively. Conclusions: Choosing a cutpoint in this age group should be based on the exposure of interest, epoch/observation interval duration, and required degree of stringency for classifying physical activity level.

Effects of a Bug-in-the-Ear Intervention to Increase Physical Activity Prompting and Level during Preschool Recess.

Teacher prompting is a means to increase preschool children’s physical activity. Twelve 4- and 5-year-olds at one preschool in the southwest U.S. participated in an ABA prompting intervention that utilized a bug-in-the-ear device to signal teachers to prompt sedentary children to increase physical activity level during unstructured recess. RM-ANOVA was used to analyze prompt rate across phases and visual analysis and Tau-U were used to analyze physical activity level (measured by accelerometry and systematic observation) across phases for the entire recess period (i.e., macro analysis). The latter methods were also used to compare accelerometer activity counts pre- and post prompt (i.e., microanalysis). Prompt rate was near zero at baseline; rose greater than 24-fold during intervention; and then dropped to near-baseline level at withdrawal. For observational data, sedentary activity and light and moderate-to-vigorous physical activity (MVPA) were statistically significantly lower and higher, respectively, during the intervention than at baseline/withdrawal. For accelerometry data, only MVPA was statistically significantly higher during the intervention than at baseline/withdrawal. Microanalysis revealed that post prompt physical activity rose and exceeded the light intensity threshold when teachers initiated prompts and rose but did not exceed the light intensity threshold under intervention prompting conditions. Prompting stimulates light physical activity immediately after sedentary activity is detected and decreases overall sedentary activity over an entire recess period.