Energy Expenditure and Enjoyment of Common Children’s Games in a Simulated Free-Play Environment Cheryl A. Howe, PhD, Patty S. Freedson, PhD, Henry A. Feldman, PhD, and Stavroula K. Osganian, MD, ScD Objective To measure the energy expenditure and enjoyment of children’s games to be used in developing a school-based intervention for preventing excessive weight gain. Study design Healthy weight (body mass index [BMI] <85 th percentile) and overweight or obese (BMI $85 th per- centile) third-grade children (15 boys; 13 girls) were recruited. In a large gymnasium, children performed 10 games randomly selected from 30 games used in previous interventions. Total energy expenditure was measured with a portable metabolic unit and perceived enjoyment was assessed using a 9-point Likert scale of facial expressions. Mean physical activity energy expenditure (PAEE = total energy expenditure minus resting metabolism) and enjoy- ment of the games were adjusted for sex and BMI classification. PAEE and enjoyment were compared using a re- peated-measures ANOVA with sex, BMI classification, and games as main effects. Results The games elicited a moderate intensity effort (mean  standard deviation = 5.0 1.3 metabolic equiva- lents, 123 36 kcal/30 min). PAEE was higher for boys than for girls (0.12 0.04 versus 0.11 0.04 kcal/kg/min) and for healthy weight compared with overweight children (0.13 0.04 versus 0.11 0.03 kcal/kg/min). Twenty-two of the 30 games elicited a sufficiently high PAEE ($100 kcal/30 min) and enjoyment ($ neutral expression) for inclusion in future school-based interventions. Conclusions Not all children’s games are perceived as enjoyable or resulted in an energy expenditure that was sufficiently high for inclusion in future physical activity interventions to prevent the excess weight gain associated with childhood obesity. (J Pediatr 2010;157:936-42). D eveloping a physical activity intervention specifically targeted to reduce excessive weight gain requires a precise estima- tion of the intervention energy expenditure. It has been suggested that the childhood obesity epidemic is a consequence of an average chronic energy surplus ranging from 100 to 165 kcal/d. 1,2 It is possible to design an activity intervention that opposes this energy surplus by first determining the energy cost of specific free-play games and activities to be implemented in a daily intervention. However, there are relatively few data on the energy cost of children’s everyday activities, including free play, because of the complex nature of this behavior. 3 Children are prone to sporadic changes in movement patterns with quick shifts between high and low intensity; 95% of their high intensity activity reportedly lasts <15 seconds. 4 Although investigators have attempted to quantify physical activity–related energy expenditure (PAEE) in children, these studies have typically mea- sured continuous, steady-state activities, such as throwing a ball or walking on a treadmill for a preset duration (3 to 20 min- utes) 5,6 rather than measuring the PAEE during the natural behavior to which children are accustomed. Few studies, from the early to mid 1900s, have measured the energy cost of children’s free-living activity using double-labeled water. 7,8 However, the activities measured in these studies neither reflect the type of activities currently observed in children nor the physical charac- teristics of today’s children. Therefore, these laboratory-based measures of PAEE do not provide appropriate empirical data to inform the development of interventions for prevention of excess weight gain in children. Advances in measurement technology, including portable indirect calorimetry, provide the freedom of movement com- bined with a ‘‘gold standard’’ of measuring EE, thus improving the ability to accurately measure the energy cost of child- ren’s free-play physical activity. The indirect assessment of children’s typical physical activity behavior is the first step in developing interventions that will positively and consistently impact childhood obesity. Therefore, the purpose of this study was to measure the energy cost and enjoyment of common children’s games in a simulated free-play environment. From the Department of Kinesiology (C.H., P.F.), University of Massachusetts, Amherst, MA; and Clinical Research Program (H.F., S.O.), Children’s Hospital Boston, Harvard Medical School, Boston, MA Supported by a contract with Children’s Hospital Boston. The authors declare no conflicts of interest. 0022-3476/$ - see front matter. Copyright Ó 2010 Mosby Inc. All rights reserved. 10.1016/j.jpeds.2010.06.041 BMI Body mass index DEx Data storage/telemetry unit EE Energy expenditure FAS Facial Affective Scale GT1M Actigraph accelerometer (model GT1M) MET Metabolic equivalent MVPA Moderate-to-vigorous physical activity ($3 METs) HW Healthy weight (BMI <85 th percentile) OM Oxycon Mobile portable metabolic analyzer OW Overweight or obese (BMI $85 th percentile) PAEE Physical activity-related energy expenditure RMR Resting metabolic rate TEE Total energy expenditure SBx Gas analyzer 936