Background and Purpose
Approximately 14.3 million American children attend summer camps(1), which may last up to 10 hours/day for up to 12 weeks.  There is some evidence that fitness gains and body weight reductions achieved from school-based interventions are not maintained during the summer months (2,3).  The evidence base is growing for the impact out-of-school time (OST) programs can have on childhood obesity prevention, but little is known about children’s activity levels in summer camps.  Two assessments using systematic observation found that 20-25%(4) and 28%(5) of children were engaged in walking or vigorous activity at any time during camp hours.  However, no known studies to date have assessed daily summer camp activity levels using accelerometers.

Objectives
To assess baseline levels of physical activity via accelerometer among elementary school children attending summer camps, and to inform adaptation of an evidence-based afterschool obesity prevention program [Out of School Nutrition and Physical Activity (OSNAP) Initiative(6)] to the summer camp setting.

Methods
This study used a cross-sectional and repeated measures design to assess accelerometer-measured physical activity levels among children ages 5-12 attending 5 summer camps in Boston, Massachusetts, from July-August 2013.  Children attending 5 camps selected via convenience sample were recruited to wear accelerometers during camp hours for one week (5 days).  Each consenting child wore an accelerometer (Actigraph GT3X/GT3X+, Pensacola, FL) on an elastic belt on the hip throughout the camp day except during swimming periods.  Data collectors visited camps each day to observe activities and distribute and collect accelerometers.  Primary outcomes were daily minutes of moderate-to-vigorous physical activity (MVPA) and vigorous physical activity (VPA) accumulated overall and occurring in bouts.  Vertical axis intensity counts captured using the low-frequency extension were converted into minutes spent in MVPA and VPA using the Freedson(7) age-specific 1-minute cut points for children, at MET thresholds of 4 and 6 METs for moderate and vigorous activity, respectively.  Linear regression analysis was used to estimate differences in daily activity levels according to demographic characteristics, adjusting for clustering of children within camps.  Associations between daily activity levels and physical activity opportunities observed will be investigated to determine sources of daily variation in activity levels within children.

Results
Among 184 children eligible and consenting to participate in the study, 153 children (83%) wore monitors on at least 2 days for at least 5 hours/day.  Camp duration was 7.5-10 hours/day.  Children were on average 7.6 (SD 1.4) years of age, and 47% were female.  Children were multi-ethnic (8% White non-Hispanic, 37% Black non-Hispanic, 27% Hispanic/Latino, 3% Asian, 25% multi-racial/other race/ethnicity).  Children wore monitors for an average of 4.2 (SD 0.9) days for 8.9 (SD 1.1) hours/day.  On average, children attending summer camps accumulated 78.0 (SD 37.5) minutes/day MVPA overall, with 38.8 (SD 31.1) minutes/day in bouts.  They accumulated 17.0 (SD 13.4) minutes/day VPA overall, with 3.2 (SD 6.8) minutes/day in bouts.  Among 77 children with 5 monitored days, 23 (30%) met recommendations for 60 minutes/day MVPA on all 5 days, and 22 (29%) met recommendations on 4 days.  Since activity levels during swimming periods were not captured via accelerometer, these results likely underestimate actual physical activity levels.  In multiple regression analysis accounting for clustering within camps, results showed that boys were more active than girls (Beta=11.9 minutes/day MVPA overall; p=0.01), and younger children were more active than older children (B=9.1 minutes/day MVPA per year of age; p<0.001).  No differences by race/ethnicity were found.  Activity levels differed significantly between camps (p<0.001; range 54.9-118.3 minutes/day MVPA), and were highly clustered among children within camps (intraclass correlation=0.37 for MVPA overall).

Conclusions
Elementary school children attending summer camps in Boston, Massachusetts achieved, on average, daily recommended levels of MVPA during camp hours.  Males and younger children engaged in higher levels of physical activity.  Both males and females achieved overall MVPA levels (86.3 and 68.6, respectively) during the camp day similar to national objectively-measured averages above 4 METs (95.4 and 75.2 for 6-11 year old males and females)(8).  Analysis of variation in activity levels according to duration and types of physical activities offered to children attending camps will provide further insight into potential areas of intervention.  Additional research will assess foods and beverages consumed in summer camps and thus describe overall energy balance among children during the summer months.

Implications for Practice and Policy
This study lays the groundwork for adapting successful OST interventions designed for traditional afterschool programs to full day summer camps.  Results indicate that activities in summer camps may need to be targeted to engage females and older children in recommended levels of physical activity.  As community leaders work to disseminate evidence-based physical activity and nutrition interventions in Boston and nationwide, these results will help them set realistic goals.  In Boston, academic and city agency partners will use these results to inform dissemination of the OSNAP intervention via the Racial and Ethnic Approaches to Community Health (REACH) Obesity and Hypertension Demonstration Project.

References

1. Afterschool Alliance. America After 3PM Special Report on Summer: Missed Opportunities, Unmet Demand. Washington, DC: Afterschool Alliance; 2010.
2. Carrel AL, Clark RR, Peterson S, Eickhoff J, Allen DB. School-based fitness changes are lost during the summer vacation. Arch Pediatr Adolesc Med. 2007;161(6):561-564.
3. Gutin B, Yin Z, Johnson M, Barbeau P. Preliminary findings of the effect of a 3-year after-school physical activity intervention on fitness and body fat: The Medical College of Georgia Fitkid Project. International Journal of Pediatric Obesity: IJPO. 2008;3(Suppl 1):3-9.
4. Beets MW, Weaver RG, Beighle A, Webster C, Pate RR. How physically active are children attending summer day camps? J Phys Act Health. 2013;10:850-855.
5. Zarrett N, Sorensen C, Skiles B. Environmental and social-motivational contextual factors related to youth physical activity: systematic observations of summer day camps. International Journal of Behavioral Nutrition and Physical Activity. 2013;10:63.
6. Harvard School of Public Health Prevention Research Center. The Out of School Nutrition and Physical Activity Initiative (OSNAP). Available at: www.osnap.org. Accessed September 4, 2013.
7. Freedson P, Pober D, Janz KF. Calibration of accelerometer output for children. Med Sci Sports Exerc. 2005;37(11):S523-S530.
8. Troiano RP, Berrigan D, Dodd KW, Masse LC, Tilert T, McDowell M. Physical activity in the United States measured by accelerometer. Med Sci Sport Exerc. 2008;40(1):181-188.

Support / Funding Source
Support for this project was provided by cooperative agreements with the Centers for Disease Control and Prevention [CDC U48DP001946]. The content is solely the responsibility of the authors and does not necessarily represent the official views of the CDC.