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Moderating influences of baseline activity levels in school physical activity programming for children: the Ready for Recess project

Pedro F Saint-Maurice1*, Gregory J Welk1, Daniel W Russell2 and Jennifer Huberty3

Author Affiliations

1 Iowa State University, Department of Kinesiology, Ames, IA 50011, USA

2 Iowa State University, Department of Human Development and Family Studies, Ames, IA 50011, USA

3 School of Nutrition & Health Promotion, Arizona State University, Phoenix, AZ 85004-0698, USA

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BMC Public Health 2014, 14:103  doi:10.1186/1471-2458-14-103

Published: 1 February 2014



A limitation of traditional outcome studies from behavioral interventions is the lack of attention given to evaluating the influence of moderating variables. This study examined possible moderation effect of baseline activity levels on physical activity change as a result of the Ready for Recess intervention.


Ready for Recess (August 2009-September 2010) was a controlled trial with twelve schools randomly assigned to one of four conditions: control group, staff supervision, equipment availability, and the combination of staff supervision and equipment availability. A total of 393 children (181 boys and 212 girls) from grades 3 through 6 (8–11 years old) were asked to wear an Actigraph monitor during school time on 4–5 days of the week. Assessments were conducted at baseline (before intervention) and post intervention (after intervention).


Initial MVPA moderated the effect of Staff supervision (β = −0.47%; p < .05), but not Equipment alone and Staff + Equipment (p > .05). Participants in the Staff condition that were 1 standard deviation (SD) below the mean for baseline MVPA (classified as “low active”) had lower MVPA levels at post-intervention when compared with their low active peers in the control condition (Mean diff = −10.8 ± 2.9%; p = .005). High active individuals (+1SD above the mean) in the Equipment treatment also had lower MVPA values at post-intervention when compared with their highly active peers in the control group (Mean diff = −9.5 ± 2.9%; p = .009).


These results indicate that changes in MVPA levels at post-intervention were reduced in highly active participants when recess staff supervision was provided. In this study, initial MVPA moderated the effect of Staff supervision on children’s MVPA after 6 months of intervention. Staff training should include how to work with inactive youth but also how to assure that active children remain active.

PA promotion; MVPA; Recess; Youth