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Jennifer L. Huberty, Michael W. Beets, Aaron Beighle and Greg Welk

Background:

The purpose of this study was to determine the effectiveness of Ready for Recess: an elementary school recess intervention targeting staff training (ST) and providing recreational equipment (EQ).

Methods:

Ready for Recess had 4 intervention schools: 1) EQ+ST, 2) EQ, 3) ST, and 4) control. Moderate-to-vigorous physical activity (MVPA) was assessed with accelerometers at the four schools in 257 3rd- to 6th-grade children. Random intercept models for overweight/obese (OWOB) and healthy weight (HW) for boys and girls separately, examined change in percentage of time spent in MVPA during recess across EQ+ST, EQ, and ST compared with the control from baseline to postintervention.

Results:

HW boys receiving EQ+ST increased MVPA by 19.4%, OWOB boys receiving ST increased MVPA by 4.5%, OWOB girls receiving EQ-ST increased MVPA by 6.0%, while HW girls receiving EQ decreased MVPA by 13.6% in comparison with the control.

Conclusions:

Ready for Recess represents a possible means to increase MVPA in OWOB girls/boys, populations least likely to meet MVPA recommendations. However, the effect of the intervention was not uniform across all subgroups.

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Pedro Silva, Ryan Lott, Jorge Mota and Greg Welk

Social support (SS) from parents and peers are key reinforcing factors in the Youth Physical Activity Promotion (YPAP) model. This study aims to identify the relative contribution of parental and peer SS on youth participation in moderate to vigorous physical activity (MVPA). Participants included 203 high school students (n = 125 girls; mean age 14.99 ± 1.55 years). MVPA was assessed by accelerometry. SS influences were evaluated using a well-established scale. Structural equation modeling measured (AMOS, Version 19) the relative fit of the YPAP models using both parental and peer SS. Parental SS had significant associations with both predisposing factors, enjoyment (β = .62, p < .01), and self-efficacy (β= .32, p < .01), as well a direct effect on MVPA (β = .30, p < .01). Peer SS had direct effect on MVPA (β = .33, p < .05), also significantly influenced levels of enjoyment (β = .47, p < .01) and self-efficacy (β = .67, p < .01). In both models self-efficacy mediated the influence on MVPA. The direct effects for parents and peers were similar. This demonstrates that both parental and peer social support exert a strong influence on adolescent MVPA.

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Richard R. Rosenkranz, Greg J. Welk and David A. Dzewaltowski

Background:

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).

Methods:

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.

Results:

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.

Conclusions:

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.

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Heather M. Hayes, Joey C. Eisenmann, Kate A. Heelen, Greg J. Welk and Jared M. Tucker

The purpose of this study was to determine the joint association of fatness and physical activity on resting blood pressure in children. Subjects included 157 children (age 5.5–9.5 years). Moderate-to-vigorous physical activity (MVPA, min/day), body fatness, and resting blood pressure were measured. Four categories were created by cross tabulation of high/normal levels of fatness and high/low levels of MVPA. There were significant differences in systolic blood pressure and mean arterial pressure across the fat/MVPA groups (p < .05). Regardless of participating in an acceptable level of MVPA, overfat children had higher resting systolic blood pressure than normal fat children. MVPA did not significantly attenuate blood pressure within a fat category.

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Pedro Silva, Luisa Aires, Rute Marina Santos, Susana Vale, Greg Welk and Jorge Mota

Background:

The purpose of the study is to evaluate age and gender differences in objectively measured levels of physical activity (PA) in a large and diverse sample of residents from an urban area in Porto, Portugal.

Methods:

Participants included 822 residents, 334 males (41%), and 488 females (59%), aged 6 to 90 years. GT1M accelerometer was used to assess daily PA over 7 consecutive days, and the measurement was from October (2007) to June (2008).

Results:

Males were more active than females. This difference was attenuated in the 2 oldest age groups (40−59 and 60+ yrs). An accentuated declined in all PA variables occurred between the youngster group (6−11 yrs) and adolescents group (12−19 yrs). Surprisingly, young adults (20−39 yrs) engaged in more moderate-to-vigorous PA (MVPA) than adolescents. Further, females also had higher MVPA in the fourth group (40−59 yrs) compared with the second group (12−19 yrs). Males had higher compliance rates of PA guidelines than females regardless the age group considered. Adolescents had very low compliance rates (females = 18.18%; males = 33.50%).

Conclusions:

Porto metropolitan area residents had low rates of compliance with current PA guidelines. A low level of PA in Porto adolescents is a matter of concern and suggests that interventions are needed.

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Jared M. Tucker, Greg Welk, Sarah M. Nusser, Nicholas K. Beyler and David Dzewaltowski

Background:

This study was designed to develop a prediction algorithm that would allow the Previous Day Physical Activity Recall (PDPAR) to be equated with temporally matched data from an accelerometer.

Methods:

Participants (n = 121) from a large, school-based intervention wore a validated accelerometer and completed the PDPAR for 3 consecutive days. Physical activity estimates were obtained from PDPAR by totaling 30-minute bouts of activity coded as ≥4 METS. A regression equation was developed in a calibration sample (n = 91) to predict accelerometer minutes of moderate to vigorous physical activity (MVPA) from PDPAR bouts. The regression equation was then applied to a separate, holdout sample (n = 30) to evaluate the utility of the prediction algorithm.

Results:

Gender and PDPAR bouts accounted for 36.6% of the variance in accelerometer MVPA. The regression model showed that on average boys obtain 9.0 min of MVPA for each reported PDPAR bout, while girls obtain 4.8 min of MVPA per bout. When applied to the holdout sample, predicted minutes of MVPA from the models showed good agreement with accelerometer minutes (r = .81).

Conclusions:

The prediction equation provides a valid and useful metric to aid in the interpretation of PDPAR results.

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Ana C. Seabra, José Maia, André F. Seabra, Greg Welk, Robert Brustad and António M. Fonseca

Background:

The Youth Physical Activity Promotion (YPAP) model provides an integrated approach to understanding the predisposing, enabling, and reinforcing factors influencing physical activity (PA) behavior. The purpose of this study was to evaluate an adapted version of the YPAP model for explaining PA among Portuguese schoolchildren.

Methods:

A random cross-sectional sample of 683 children (8–10 years of age) attending elementary public schools in the north of Portugal completed a detailed survey assessing attraction to PA, perceived physical competence, parental influences and leisure time PA. Structural equation modeling techniques were conducted (EQS6.1).

Results:

Attraction to PA was directly associated with children’s PA participation (β = 0.271, P < .05). Perceived physical competence imposed an indirect effect on children’s PA through children’s attraction to PA (β = 0.253, P < .05). Parental influence had an indirect effect on children’s PA through perceived physical competence and attraction to PA (β = 0.318 and 0.662, respectively, P < .05). Perceived physical competence and parental influence were not directly associated with children’s PA (β = 0.069 and 0.180, respectively, P > .05).

Conclusions:

The adapted version of YPAP model was useful in explaining PA participation in elementary Portuguese schoolchildren. Intervention programs intended to enhance attraction to PA, perceived physical competence and favorable parental influence should be developed to promote children’s PA participation.

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Greg Welk, Youngwon Kim, Robin P. Shook, Laura Ellingson and Roberto L. Lobelo

Background:

The study evaluated the concurrent and criterion validity of a new, disposable activity monitor designed to provide objective data on physical activity and energy expenditure in clinical populations.

Methods:

A sample of healthy adults (n = 52) wore the disposable Metria IH1 along with the established Sensewear armband (SWA) monitor for a 1-week period. Concurrent validity was examined by evaluating the statistical equivalence of estimates from the Metria and the SWA. Criterion validity was examined by comparing the relative accuracy of the Metria IH1 and the SWA for assessing walking/running. The absolute validity of the 2 monitors was compared by computing correlations and mean absolute percent error (MAPE) relative to criterion data from a portable metabolic analyzer.

Results:

The output from 2 monitors was highly correlated (correlations > 0.90) and the summary measures yielded nearly identical allocations of time spent in physical activity and energy expenditure. The monitors yielded statistically equivalent estimates and had similar absolute validity relative to the criterion measure (12% to 15% error).

Conclusions:

The disposable nature of the adhesive Metria IH1 monitor offers promise for clinical evaluation of physical activity behavior in patients. Additional research is needed to test utility for counseling and behavior applications.

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David A. Dzewaltowski, Konstantinos Karteroliotis, Greg Welk, Judy A. Johnston, Dan Nyaronga and Paul A. Estabrooks

This study developed youth self-efficacy (SEPA) and proxy efficacy (PEPA) measures for physical activity (PA). Proxy efficacy was defined as a youth’s confidence in his or her skills and abilities to get others to act in one’s interests to create supportive environments for PA. Each spring of their sixth-, seventh-, and eighth-grade years, middle school students completed SEPA and PEPA questions and then, for 3 days, recalled their previous day’s after-school PA. Exploratory and confirmatory factor analyses revealed a four-factor structure (SEPA for 1–3 days, SEPA for 5–7 days, PEPA-Parents, PEPA-School). Across study years, SEPA 1–3 days and 5–7 days increased and PEPA-Parents and PEPA-School decreased. Initial levels of PEPA-Parents and SEPA scales were associated with initial levels of PA. From sixth through seventh grade, changes in SEPA scales were associated with changes in PA. Studies should test whether interventions targeting self-efficacy and proxy efficacy influence PA.

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Kathryn J. DeShaw, Laura Ellingson, Yang Bai, Jeni Lansing, Maria Perez and Greg Welk

Purpose: To advance research practices with consumer monitors, standard validation methods are needed. This study provides an example of best practices through systematically evaluating the validity of the Fitbit Charge (FBC) under free-living conditions using a strong reference measure and robust measurement agreement methods. Methods: 94 healthy participants (M age 41.8 ±9.3 yrs) wore a FBC and two research grade accelerometers (Actigraph GT3X and activPAL) as they went about normal activities for a week. Estimated daily minutes of moderate to vigorous physical activity (MVPA) from the FBC were compared against reference estimates obtained from the Sojourns Including Posture (SIP) methodology, while daily step counts were compared against the activPAL. Results: Correlations with reference indicators were high for average daily MVPA (r = 0.8; p < .0001) and steps (r = 0.76; p < .0001), but the FBC overestimated time spent in MVPA by 56% and steps by 15%. The mean absolute percent errors of MVPA and steps estimated by FBC were 71.5% and 30.0%, respectively. Neither of the MVPA and step estimates from the FBC fell into the ±10% equivalence zone set by the criterion. The Kappa statistics of the classification agreement between the two MVPA assessment methods was 0.32 with a low sensitivity of 30.1% but a high specificity of 96.7%. Conclusion: The FBC overestimated minutes of MVPA and steps when compared to both reference assessments in free-living conditions. Standardized reporting in future studies will facilitate comparisons with other monitors and with future versions of the FBC.