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Keywords:

  • School-based intervention;
  • obesity prevention;
  • physical activity

Summary

  1. Top of page
  2. Summary
  3. What is already known about this subject
  4. What this study adds
  5. Introduction
  6. Methods
  7. Results
  8. Discussion
  9. Acknowledgements
  10. Conflict of Interest Statement
  11. References

Background

Schools provide a prime environment for interventions that attempt to increase physical activity and prevent obesity.

Objective

This study examined the effect of a 30-min, structured recess using 22 games of known energy expenditure on moderate-to-vigorous physical activity when compared to free play implemented with third graders from two elementary schools over 9 weeks.

Methods

Moderate-to-vigorous physical activity and other cardiovascular risk factors were assessed pre- and post-intervention in 27 children.

Results

Moderate-to-vigorous physical activity during recess increased significantly in intervention school children from 6.9 ± 0.8 to 14.9 ± 0.9 min pre- and post-intervention, respectively (adjusted mean change 8.0 ± 1.1; P < 0.0001), with no differences by gender or body mass index (BMI). In-school, moderate-to-vigorous physical activity also increased significantly more for intervention compared to control children (adjusted mean change 14 ± 4 min vs. 3 ± 3 min; P = 0.014, respectively).

Conclusion

There was no significant difference in BMI and cardiovascular risk factors. A structured recess is feasible to implement and can significantly increase moderate-to-vigorous physical activity.


What is already known about this subject

  1. Top of page
  2. Summary
  3. What is already known about this subject
  4. What this study adds
  5. Introduction
  6. Methods
  7. Results
  8. Discussion
  9. Acknowledgements
  10. Conflict of Interest Statement
  11. References
  • Most US schools offer recess, but children do not use this opportunity to be physically active.
  • A more structured recess has been shown to increase MVPA to a greater extent than free play recess.
  • Physical activity is positively associated with enjoyment in children.

What this study adds

  1. Top of page
  2. Summary
  3. What is already known about this subject
  4. What this study adds
  5. Introduction
  6. Methods
  7. Results
  8. Discussion
  9. Acknowledgements
  10. Conflict of Interest Statement
  11. References
  • Using enjoyable and energy tested games, it is feasible for most children to expend 100 kcal/30 min during recess.
  • Children participating in structured recess significantly increased MVPA during recess and the total school day.

Introduction

  1. Top of page
  2. Summary
  3. What is already known about this subject
  4. What this study adds
  5. Introduction
  6. Methods
  7. Results
  8. Discussion
  9. Acknowledgements
  10. Conflict of Interest Statement
  11. References

The cause of paediatric obesity has been attributed, in part, to a decrease in physical activity (PA) [1]. Schools provide a prime environment for interventions that attempt to increase moderate-to-vigorous physical activity (MVPA) and prevent obesity, and recess provides one opportunity to impact MVPA and body mass index (BMI). Nearly three quarters of elementary schools across the United States offer regular recess for all grades [2], but children do not use this opportunity to be physically active [3, 4]. A more structured recess has been shown to increase MVPA to a greater extent than a free-play recess, but its social and emotional benefits relative to free-play recess remain unknown and controversial [5]. In addition, enjoyment has been reported as the most important factor affecting participation in PA among children [6]; however, most interventions have not assessed the enjoyment of activities that were implemented.

We previously evaluated several children's games [7] to develop a selection of games that would approximate the purported daily energy imbalance associated with paediatric obesity [8] and be perceived as enjoyable. The purpose of this pilot study was to assess the feasibility and impact of implementing enjoyable games that generated at least 100 kcal of physical activity energy expenditure (PAEE) during a structured recess and determine whether children participating in structured as compared to free-play recess demonstrate greater increases in MVPA and more favourable changes in BMI.

Methods

  1. Top of page
  2. Summary
  3. What is already known about this subject
  4. What this study adds
  5. Introduction
  6. Methods
  7. Results
  8. Discussion
  9. Acknowledgements
  10. Conflict of Interest Statement
  11. References

Two schools from Springfield, MA participated in the study and self-selected to be an intervention (INT) school, offering a daily structured recess for 30 min or control (CON) school, offering 30 min of free play daily to all third graders (45 INT and 72 CONT school children) over 9 weeks. All children who participated in the measurement portion of this study had parental informed consent and gave assent. The study was conducted in Spring of 2009 and was approved by the University of Massachusetts and Children's Hospital Boston Institutional Review Boards.

Structured recess was led by trained research staff. It consisted of 22 games that were selected from other elementary school PA intervention studies [9, 10] with input from a focus group of elementary school physical education teachers [7]. The games were perceived as enjoyable with a score of 5 or more on a 9-point faces scale [11] and were measured to elicit a PAEE of at least 100 kcal/30 min [7]. These games also included ‘age-appropriate and enjoyable’ activities described in the current PA guidelines for children [12]. INT classroom teachers (n = 2) completed a survey that asked for feedback on the structured recess at the end of the 9 weeks.

All measures were conducted in schools at baseline and at the end of 9 weeks. PA was measured with the Actigraph GT1M (ActiGraph, Pensacola, FL, USA) monitor for seven consecutive days using the ActiLife Software, version 4.0.4 (Actigraph). The GT1M was initialized to sample data in 5-s epochs. Any period of at least 30 min of consecutive zeros was omitted from the analyses. On the first and last school day at each time point, in-school accelerometry was limited to a half day (210 min); otherwise, the target was a full day (420 min). Children wore the accelerometers for an average of 4.7(standard deviation [SD] 1.2) school days at baseline and 4.4 (SD 1.4) school days at follow-up with 26 children at baseline and 25 children at follow-up wearing it for two or more school days. In INT schools, 11 children at baseline and 10 at children at follow-up wore the accelerometer for two or more of the targeted recess periods (mean number of recess periods worn was 4.0 [SD 1.2] at baseline and 3.7 [SD 1.2] at follow-up). Using age-specific accelerometer cut points [13], time spent in all PA intensity categories (Table 1) and in sedentary behaviour (SB; <100 counts min−1) were calculated for the recess and the school day. Published age-specific prediction equations were used to estimate PAEE from accelerometer data [13]. To measure the exposure to PA opportunities during the school day, the classroom teachers at the INT and CON schools were asked to complete a calendar and record the number of minutes offered for recess, PE or other special events during the same single randomly selected week of the intervention period.

Table 1. Intervention school changes in physical activity during recess from baseline to follow-up: overall, by sex and by weight class
ActivityaSubgroupBaselineFollow-upChangeP (change)bP (interaction)c
  1. a

    Mean ± SEM for 30-min recess period, intervention school only, adjusted for sex and BMI class and accounting for intra-individual correlation by mixed-model ANOVA.

  2. b

    Testing for non-zero mean change within the group.

  3. c

    Testing for differential change between subgroups.

  4. LPA, light PA; MPA, moderate PA; MVPA, moderate-to-vigorous PA (sum of MPA, VPA and VVPA); NW, normal weight; OW, overweight; PA, total physical activity; PAEE, physical activity energy expenditure; SB, sedentary behaviour; VPA, vigorous PA; VVPA, very vigorous PA.

PA, minAll11.9 ± 0.721.0 ± 0.89.1 ± 1.1<0.0001
Boys12.8 ± 0.920.7 ± 1.07.9 ± 1.3<0.00010.30
Girls11.0 ± 1.221.3 ± 1.410.3 ± 1.8<0.0001 
NW10.9 ± 1.021.1 ± 1.310.3 ± 1.6<0.00010.28
OW13.0 ± 1.020.9 ± 1.07.9 ± 1.5<0.0001 
LPA, minAll5.1 ± 0.36.1 ± 0.31.1 ± 0.40.003
Boys5.4 ± 0.35.7 ± 0.30.2 ± 0.40.560.02
Girls4.7 ± 0.46.6 ± 0.51.9 ± 0.60.001 
NW4.8 ± 0.45.8 ± 0.41.0 ± 0.50.050.89
OW5.4 ± 0.46.5 ± 0.41.1 ± 0.50.018 
MPA, minAll4.9 ± 0.49.2 ± 0.54.3 ± 0.6<0.0001
Boys5.3 ± 0.59.2 ± 0.53.8 ± 0.7<0.00010.48
Girls4.5 ± 0.79.3 ± 0.84.7 ± 1.0<0.0001 
NW4.2 ± 0.69.2 ± 0.75.1 ± 0.9<0.00010.21
OW5.7 ± 0.69.2 ± 0.63.5 ± 0.8<0.0001 
VPA, minAll1.6 ± 0.44.2 ± 0.42.7 ± 0.4<0.0001
Boys1.6 ± 0.54.4 ± 0.52.8 ± 0.5<0.00010.79
Girls1.5 ± 0.64.0 ± 0.62.6 ± 0.60.0001 
NW1.5 ± 0.54.4 ± 0.62.9 ± 0.6<0.00010.56
OW1.6 ± 0.54.1 ± 0.52.5 ± 0.5<0.0001 
VVPA, minAll0.4 ± 0.11.4 ± 0.21.0 ± 0.2<0.0001
Boys0.4 ± 0.21.3 ± 0.20.9 ± 0.2<0.00010.70
Girls0.4 ± 0.21.4 ± 0.31.1 ± 0.30.0005 
NW0.5 ± 0.21.6 ± 0.21.1 ± 0.3<0.00010.51
OW0.3 ± 0.21.2 ± 0.20.9 ± 0.20.0004 
MVPA, minAll6.9 ± 0.814.9 ± 0.98.0 ± 1.1<0.0001
Boys7.5 ± 1.015.0 ± 1.07.6 ± 1.3<0.00010.66
Girls6.4 ± 1.314.9 ± 1.48.5 ± 1.7<0.0001 
NW6.2 ± 1.115.4 ± 1.39.1 ± 1.6<0.00010.27
OW7.6 ± 1.114.5 ± 1.16.9 ± 1.4<0.0001 
SB, minAll18.0 ± 0.78.9 ± 0.8−9.1 ± 1.1<0.0001
Boys17.1 ± 0.99.2 ± 1.0−7.9 ± 1.3<0.00010.30
Girls18.9 ± 1.28.7 ± 1.4−10.2 ± 1.8<0.0001 
NW19.1 ± 1.08.8 ± 1.3−10.2 ± 1.6<0.00010.28
OW17.0 ± 1.09.1 ± 1.0−7.9 ± 1.5<0.0001 
PAEE, kcalAll99 ± 6155 ± 656 ± 7<0.0001
Boys103 ± 7156 ± 853 ± 9<0.00010.69
Girls95 ± 9154 ± 1059 ± 12<0.0001 
NW96 ± 8160 ± 964 ± 11<0.00010.26
OW102 ± 8150 ± 848 ± 9<0.0001 

Resting blood pressure and heart rate were measured using an automated blood pressure device (GE Dinamap ProCare 100, Piscataway, NJ, USA). Height was measured using a portable stadiometer (Seca Road Rod 214, Snoqualmie, WA, USA), and weight was measured using a portable digital scale (Lifesource ProFit, Milpitas, CA, USA). BMI was calculated as weight (kg)/height (m2). Children were classified as overweight/obese (BMI% ≥ 85%) using Centers for Disease Control age and sex-specific growth charts [14]. Waist circumference was measured using a Gulick tape at the horizontal line between the suprailiac crests.

Mixed-model analysis of variance (ANOVA) was used to assess differences in PA and physical measures between schools at baseline and changes in these measures from baseline to follow-up. Each day of accelerometer data for each participant and time point was treated as a single unit of analysis. To examine the effects in INT schools during recess only, the ANOVA included time point as a main effect, as well as adjustments for gender and overweight and random effects to account for participant-to-participant and day-to-day (residual) variation. For the INT and CON school comparisons, the ANOVA additionally included school condition as a main effect and a condition (INT and CON school) × time interaction to examine in-school effects. Analysis for recess effects included all INT schools days on which the accelerometer was worn for the full 30 min of recess time. Analysis of in-school effects was restricted to school days on which the accelerometer was worn for at least 95% of the full day (420 min) or 95% of a half-day session (210 min) and stratified to account for the difference in duration. Stratum-specific adjusted mean changes and differences are reported for the full-day stratum only. Statistical analyses were performed using SAS version 9.2 (SAS Institutes, Inc., Cary, NC, USA). A P-value < 0.05 was considered statistically significant.

Results

  1. Top of page
  2. Summary
  3. What is already known about this subject
  4. What this study adds
  5. Introduction
  6. Methods
  7. Results
  8. Discussion
  9. Acknowledgements
  10. Conflict of Interest Statement
  11. References

Twenty-seven children, 11 (24%) from INT schools and 16 (22%) from CON schools, participated in the evaluation. Approximately half were female, half were classified as overweight/obese, and 81% were Hispanic. Demographic and physiologic variables were similar between conditions at baseline.

Moderate-to-vigorous physical activity during the structured recess increased significantly in intervention school children from 6.9 ± 0.8 min at baseline to 14.9 ± 0.9 min at follow-up (adjusted mean change 8.0 ± 1.1 min; P < 0.0001), resulting from increases in both moderate and vigorous intensities of PA (Table 1). There was also a significant increase in total PA (adjusted mean change 9.1 ± 1.1 min; P < 0.0001), resulting from a significant increase in light PA (LPA) as well as moderate PA (MPA) and vigorous PA (VPA). INT children showed a significant increase in PAEE from 99.1 ± 6 kcal at baseline to 155 ± 6 kcal follow-up (adjusted mean change 56 ± 7 kcal, P < 0.0001). At baseline, only 39% of children expended ≥100 kcal of PAEE during recess as compared to 89% of children at follow-up (odds ratio 12.89; 95% confidence interval 4.26–38.94). There were no significant differences by gender or overweight status.

Time spent in MVPA during the school day increased significantly more in INT children than in CON children (14 ± 4 vs. 3 ± 3 min, respectively; P = 0.014), resulting from greater increases in both MPA and VPA (Table 2). There was also a significantly greater increase in total minutes of PA in INT compared to CON children (20 ± 6 vs. −2 ± 4 min, respectively; P = 0.003), resulting from a significantly greater increases in LPA as well as MPA and VPA. SB declined significantly in INT children (−19 ± 6 min; P = 0.001) and increased slightly in CON children (2 ± 4 min; P = 0.58) resulting in a significantly greater decline of −22 ± 7 min (P = 0.003) in INT compared to CON children. INT children showed a larger and significant increase in PAEE (84 ± 25 kcal; P = 0.0008) compared to a lesser, non-significant increase in the CON children (28 ± 17 kcal; P = 0.10), but the difference was not significant (mean net change 56 ± 30 kcal; P = 0.06). Analyses omitting the half days gave similar but less precise results (data not shown). There were no significant differences by gender or overweight status (data not shown). In addition, both INT and CON children increased their out-of-school MVPA (20 ± 7 vs. 11 ± 5 min, respectively), but these changes were not significantly different (mean net change 9.0 ± 8; P = 0.27).

Table 2. During the school day changes in physical activity from baseline to follow-up by school condition
ActivityaSchoolBaselineFollow-upChangeP (change)bNet changeP (interaction)c
  1. a

    Mean ± SEM for full school day (accelerometer worn for at least 95% of 420-min school day), adjusted for sex and BMI class, from mixed-model ANOVA stratified by length of school day (full or half) and accounting for intra-individual correlation.

  2. b

    Testing for non-zero mean change within the school.

  3. c

    Testing for differential (net) change between INT and CON school.

  4. LPA, light PA; MPA, moderate PA; MVPA, moderate-to-vigorous PA (sum of MPA, VPA and VVPA); PA, total physical activity; PAEE, physical activity energy expenditure; SB, sedentary behaviour; VPA, vigorous PA; VVPA, very vigorous PA.

Total PA (min)INT129 ± 5149 ± 620 ± 60.001022 ± 70.003
CON109 ± 4106 ± 4−2 ± 40.58
LPA (min)INT68 ± 374 ± 36 ± 30.0411 ± 40.002
CON63 ± 258 ± 2−5 ± 20.014
MPA (min)INT50 ± 360 ± 39 ± 30.0018 ± 30.03
CON38 ± 240 ± 22 ± 20.44
VPA (min)INT8.6 ± 0.912.2 ± 0.93.6 ± 0.90.00012.9 ± 1.10.010
CON6.2 ± 0.76.8 ± 0.70.7 ± 0.60.29
VVPA (min)INT1.7 ± 0.42.8 ± 0.41.0 ± 0.40.0120.6 ± 0.50.26
CON1.4 ± 0.31.8 ± 0.30.5 ± 0.30.10
MVPA§ (min)INT61 ± 375 ± 414 ± 40.000211 ± 50.014
CON46 ± 349 ± 33 ± 30.30
SB (min)INT291 ± 5271 ± 6−19 ± 60.001−22 ± 70.003
CON311 ± 4314 ± 42 ± 40.58
PAEE (kcal)INT736 ± 40820 ± 4184 ± 250.000856 ± 300.06
CON727 ± 34756 ± 3428 ± 170.10

INT children gained less body weight on average than CON children (0.4 ± 0.4 kg; P = 0.29 and 1.4 ± 0.3 kg; P = 0.0001, respectively); yet, there was no significant change in BMI (−0.2 ± 0.2 vs. 0.1 ± 0.2 kg m−2 for INT vs. CON children, respectively; P = 0.30). There were also no significant changes in waist circumference, blood pressure or heart rate between conditions.

During one randomly selected week of the 9-week intervention period, time available for recess was greater for the CON compared to INT school (150.0 ± 0.0 vs. 128.0 ± 11.3 min week−1), and the CON school reported more time for physical education classes (40 min d−1 vs. 40–90 min week−1). Teachers from the two classrooms participating in the intervention rated the structured recess highly (9.1 on a 10-point Likert scale) with respect to children's enjoyment. They also felt positive social and teamwork skills observed among the children while playing the games spilled over into the classroom and improved conflict resolution as well as promoted an environment that was more conducive to learning.

Discussion

  1. Top of page
  2. Summary
  3. What is already known about this subject
  4. What this study adds
  5. Introduction
  6. Methods
  7. Results
  8. Discussion
  9. Acknowledgements
  10. Conflict of Interest Statement
  11. References

Schools provide a setting for youth to accumulate a substantial portion of nationally recommended levels of MVPA [15] in a manner that is equally accessible to all children. We found that a structured recess was feasible for the study staff to implement in the school setting and that children participating in the structured recess demonstrated a significant 8.0 min increase in time spent in MPVA, with percent of time spent in MVPA during the 30-min period increasing from 23% to 49.7%. In addition, children participating in the structured recess compared to free-play recess demonstrated greater increases in in-school MVPA levels. The majority of children (89%) also either met or exceeded the target threshold of 100 kcal PAEE during the structured recess. The estimated average increase of 56 kcal in daily PAEE that was observed in this pilot was, however, not sufficient to positively impact BMI over 9 weeks.

Previous school-based interventions attempting to increase MVPA outside of physical education classes or during recess without increasing time available for recess have not been consistently associated with increases in MVPA. Stratton and Mullen [16] conducted a randomized trial in eight primary schools using multicolour playground markings and found that time spent in MVPA increased significantly in intervention schools (36.7% to 50.3%) while it declined in control schools (39.9% to 33.4%) after 4 months as assessed by heart rate monitors. In a larger, longitudinal, controlled trial conducted by Ridgers et al. [17-19] in 26 elementary schools, redesigning a playground environment with markings and physical structures promoted a 4.5% significantly greater absolute increase in percent of time spent in MVPA as measured by accelerometers at 6 months [17] but not at 6 weeks [18]. The effect of the intervention was found to be strongest at 6 months, and declined and was not significant at 12 months [19]. In a randomized trial conducted in seven elementary schools, Verstraete et al. [20] found that providing game equipment along with teacher encouragement to play the games significantly increased the proportion of time spent in MVPA after 3 months during lunch break, but not morning recess. Time spent in MVPA increased from 48% to 68% of recess in intervention school compared to a decline from 55% to 45% in control schools, as measured by accelerometers [20]. Whereas, more recently, Huberty et al. [21] evaluated the impact of a recess intervention conducted over one school year that included school staff training on implementing activities with children, activity zone maps and playground equipment and activity cards with third through fifth graders in two elementary schools, and using accelerometers, found that children significantly increased their time spent in moderate (18.1% to 31.2%) or vigorous (7.2% to 16.8%) PA. Finally, more organized and instructor-led fitness breaks have shown the highest proportion of time spent in MVPA. Scruggs et al. [22] found that in 27 fifth graders, children spent significantly more time in MVPA during the structured fitness break (14.23 min; 93%) when compared to 15 min free-play morning (3.45 min; 23%) or lunch recess (9.4 min; 63%) as assessed by heart rate monitors. A more structured or facilitated recess may be needed to more effectively and consistently increase MVPA as well as to maximize the proportion of time spent in MVPA by young children.

Our study has strengths and limitations. The use of accelerometers to objectively measure PA strengthens the internal validity of our findings. In addition, the intervention implemented games that were previously tested and shown to be acceptable and enjoyable to children as well as promote a desired threshold level of PAEE in children. However, given the non-randomized design and small sample size, it is possible that confounding caused by factors not included in our analyses might account for the differences in PA levels that were observed between the schools. In addition, the small and homogeneous sample of children may limit the generalizability of our findings, and it is unknown whether this intervention would be feasible and sustainable in schools if implemented by school staff rather than study personnel.

Larger, randomized trials are necessary to determine the feasibility of implementing the intervention with school personnel, its effectiveness compared to free play, and whether this can have a positive impact on BMI over a longer duration. In addition, given the demonstrated benefits of unstructured recess in promoting the social and emotional development of the whole child [5], it will be important to determine the impact of a structured recess relative to free play on children's behaviour, social skills and learning in the classroom.

Acknowledgements

  1. Top of page
  2. Summary
  3. What is already known about this subject
  4. What this study adds
  5. Introduction
  6. Methods
  7. Results
  8. Discussion
  9. Acknowledgements
  10. Conflict of Interest Statement
  11. References

All authors have made substantial contributions in the manuscript including the conception and design or analysis and interpretation of the data; drafting the article or revising it critically for important intellectual content; and final approval of the version to be published. The study was funded by Children's Hospital Boston. The sponsoring institution had no role in the preparation of the manuscript. There was no pharmaceutical company funding.

References

  1. Top of page
  2. Summary
  3. What is already known about this subject
  4. What this study adds
  5. Introduction
  6. Methods
  7. Results
  8. Discussion
  9. Acknowledgements
  10. Conflict of Interest Statement
  11. References
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