This study sought to assess criterion validity of the Actical monitor step-count function in children via ankle and waist placement, compared with observed video recordings. Children attending a summer program (12 boys, 7 girls, mean age = 9.6yrs, range 7–11yrs) wore two synchronized Acticals, attached at the ankle (AA) and waist (AW). Children performed treadmill walking at varying speeds, and two research assistants counted steps using observed video recordings (OVR). Results showed high correlations for AW-OVR (r = .927, p < .001) and AA-OVR (r = .854, p < .001), but AW and AA were significantly lower than OVR (t > 11.2, p < .001). AW provided better step estimates than AA for step rates above 130 steps per minute. In contrast, AA was superior to AW for slow walking, and measured more steps during the (nontreadmill) program time. Overall, the Actical monitor showed good evidence of validity as a measure of steps in children for population-based studies.
Richard R. Rosenkranz, Sara K. Rosenkranz, and Casey Weber
David A. Dzewaltowski and Richard R. Rosenkranz
Positive youth development (PYD) is an emerging area of study and practice that targets fostering the assets of young people to avoid problem behaviors and excel in meeting diverse life challenges. This paper describes how PYD evolved from treating problem behaviors to preventing problem behaviors in at-risk youth, to more recently helping all youth thrive and excel in numerous domains. Although evidence to inform community policy and practice has emerged, there is a lack of consensus on how to define PYD, and this lack of consensus has impacted progress in PYD physical activity behavioral science. This paper recommends PYD physical activity behavioral science reject disciplinary boundaries and (a) examine the nature of person-environment interaction in the context of physical activity as the primary outcome, (b) target big-picture physical activity outcome questions, and (c) come to a consensus on the domains of physical activity behavioral science research competencies.
Brooke J. Cull, Mark. D. Haub, Richard R. Rosenkranz, Thomas Lawler, and Sara K. Rosenkranz
Sedentary time is an independent risk factor for chronic diseases and mortality. It is unknown whether active adults alter their dietary and/or physical activity behaviors in response to imposed sedentary time, possibly modifying risk. The aim of this study was to determine whether imposed sedentary time would alter typical behaviors of active adults.
Sixteen physically active, young adults were randomized to the no-intervention control (CON, n = 8) group or the sedentary-intervention (SIT, n = 8) group. SIT participants attended monitored sedentary sessions (8 wk, 10 h/wk). Assessments including diet and physical activity occurred at baseline, week 4, and week 9.
There were no differences (P > .05) between CON and SIT groups for step counts or time spent in sedentary, light, moderate, or vigorous physical activity when comparing a week during imposed sedentary time (week 4) to baseline and week 9. At week 4, caloric intake was not different from baseline (P > .05) in either group. Caloric intake decreased significantly (P > .05) in SIT from baseline to week 9.
Active adults did not alter physical activity or dietary behaviors during the imposed sedentary intervention. However, SIT reduced caloric intake from baseline to week 9, indicating a possible compensatory response to imposed sitting in active adults.
Richard R. Rosenkranz, Chad M. Cook, and Mark D. Haub
To illustrate the effects of low-carbohydrate (LC) and grain-based (GB) diets on body composition, biomarkers, athletic training, and performance in an elite triathlete.
The athlete followed 2 dietary interventions for 14 d while maintaining a prescheduled training program. Pre- and post intervention measurements for each diet included plasma and serum samples, resting energy expenditure, body composition, and a performance bike ride.
Compared with the GB diet, the LC diet elicited more disruptions to training and unfavorable subjective experiences. Total cholesterol, HDL cholesterol, LDL cholesterol, ratings of perceived exertion, and heart rate were elevated on the LC diet. Blood insulin, resting lactate, post exercise lactate, and C-reactive protein were lowest on the LC diet.
The LC diet resulted in both favorable and unfavorable outcomes. The primary observation was a disruption to scheduled training on the LC diet. Researchers should consider how the potential mediating effect of disruptions to training could influence pretest–posttest designs.
Richard R. Rosenkranz, Greg J. Welk, and David A. Dzewaltowski
Active recreation sessions taking place within after-school programs (ASP) present an opportunity for attending children to attain part of the recommended 60 minutes of daily moderate-to-vigorous physical activity (MVPA). This cross-sectional study’s purpose was to assess relationships between microlevel ASP environmental characteristics and physical activity and sedentary behavior (SED).
During 161 ASP active recreation sessions, 240 children from 7 schools wore Actigraph GT1M accelerometers and were observed up to 6 times per year, over 3 years. To provide microlevel environmental data, trained observers recorded session times, location, duration, organization, equipment, and number of children and staff. Unadjusted bivariate correlations and multivariable regression analyses were used to assess the influence of microlevel environmental variables on MVPA and SED, with regression models controlling for relevant covariates.
Across all ASP active recreation sessions, children spent 39 ± 15% in MVPA and 16 ± 11% in SED. Session location, boy-to-girl ratio, and duration were significantly related to MVPA in the regression model. For SED, location and duration were significant influences in the model.
Both location and duration appear to be modifiable correlates of group physical activity level, which may serve to inform intervention efforts to promote physical activity in ASP.
Michaela A. Schenkelberg, Richard R. Rosenkranz, George A. Milliken, and David A. Dzewaltowski
Children with Autism Spectrum Disorders (ASD) may be at greater risk for not meeting physical activity (PA) guidelines than neurotypical children (NT). The purpose of this study was to explore setting (free play versus organized) and social group composition influences on PA of children with ASD during summer camp.
Data were collected on 6 ASD and 6 NT boys (aged 5 to 6 years) attending an inclusive summer camp. During free play and organized activity, research assistants observed the camp’s social environment and children’s PA using a modified version of the Observational System for Recording Physical Activity of Children—Preschool version.
In free play, children with ASD spent significantly less time in Moderate-Vigorous PA (MVPA) while with a peer (1.2%), compared with a peer group (11.5%) or alone (13.2%). They demonstrated significantly more Light-Moderate-Vigorous PA (LMVPA) while in a solitary social context (68.2%) compared with alone with an adult (25.8%), alone with a peer (34.8%), or with a peer group (28.2%). No significant differences were noted during organized activity.
Features of the social environment may influence PA levels of children with ASD. Specifically, certain social group contexts may be more PA-promoting than others depending on the setting.