Add After-School Physical Activity Program

The After-School YMCA-Driven Food and Fitness Project found an increase of 10.5 minutes of moderate-to-vigorous physical activity in children ages 5 to 11 years old. The evaluation was conducted in after-school programs operated by the YMCA. Using a quasi-experimental design, data was collected from 16 sites within 4 metropolitan YMCA associations in the Pacific Northwest, Midwest, South, and Eastern United States from fall 2006 to spring 2007.

Sixteen control sites were also matched to the 16 intervention sites with the same associations based on size, racial/ethnic breakdown (percent white), education (percent high school graduate), and socioecnomic status (median household income and percent of households with children below the poverty level) using zip code areas.

Implementation varied among the sites, but it was assumed that the intervention began in October 2006 for data collection purposes. Outcome changes were collected again in May to June 2007, with a total of 6 months intervention time.

The physical activity portion of the environmental standards set by the program are (1) to include moderate, fun, physical activity for every kid every day (30 minutes after-school programs; 60 minutes holiday and vacation programs) and include outdoor activity whenever possible; (2) offer vigorous, fun, physical activity as an option three times a week, 20 minutes each time; and (3) highly encourage staff to participate in physical activities with the children.

ActiGraph accelerometer data were collected from a sample of 212 children, ages 5 to 11 years. On average, 3 days of data were gathered. The data indicated that children in intervention sites showed greater increases in average physical activity and more minutes of moderate and vigorous physical activity (MVPA) than in control sites. On average, there was an increase of 10.5 minutes of moderate and vigorous physical activity.

A conservative value of 4.5 Metabolic Equivalent of Task (MET) value is to calculate MVPA, as used in Wu et al. METs is a physiological measure that expresses the energy cost of physical activities. A value of 1.0 METs is considered the baseline resting metabolic rate when sitting quietly.

On average, a school year is 180 days. The intervention assumes that the change is over the course of a school year (so if 10 minutes are added per day, it is added for 180 days). The total caloric impact is then averaged over 365 days to account for no change in activity on holidays, weekends, and summer vacation.

* The Average Caloric Impact (ACI) for this intervention is empirical, based on published estimates of METs expended, taken from trial data from Gortmaker et al. (2012), which estimates 4.0 METs in the intervention. 4.5 METs is used here as a conservative composite target based on Wu et al. (2011). The baseline and target METs for all ages are based on Ainsworth et al. (2000) and Ridley et al. (2008).

Studies Used in Estimates

Ainsworth BE, Haskell WL, Whitt MC, Irwin ML, Swartz AM, Strath SJ, O'Brien ML, Bassett Jr. DR, Schmitz KH, Emplaincourt PO, Jacobs Jr. DR, & Leon AR. Compendium of Physical Activities: an update on activity codes and MET intensities. Medicine & Science in Sports & Exercise. 2000; 32(9 Suppl):S498-504.

Gortmaker SL, Lee RM, Mozaffarian RS, Sobol AM, Nelson TF, Roth BA, Wiecha JL. Effect of an After-School Intervention on Increases in Children's Physical Activity. Medicine and Science in Sports and Exercise 2012 Mar; 44(3):450-457.

Mozaffarian RS, Wiecha JL, Roth BA, Nelson TF, Lee RM, Gortmaker SL. Impact of an Organizational Intervention Designed to Improve Snack and Beverage Quality in YMCA After-School Programs. American Journal of Public Health 2012 May; 100(5):925-932.

Mozaffarian RS, Andry A, Lee RM, Wiecha JL, Gortmaker SL. Price and Healthfulness of Snacks in 32 YMCA After-School Programs in 4 US Metropolitan Areas, 2006-2008. Preventing Chronic Disease 2012 Jan; 9:E38.

Ridley K, Olds TS. Assigning Energy Costs to Activities in Children: A Review and Synthesis. Medicine & Science in Sports & Exercise. 2008; 40(8):1439–1336.

Wu S, Cohen D, Shi Y, Pearson M, Sturm R. Economic Analysis of Physical Activity Interventions. American Journal of Preventive Medicine 2011 Feb; 40(2):149-158.