Pediatrics reports that children in preschools with high quality scores, less fixed playground equipment, more portable playground equipment, less media time and larger playgrounds experienced more moderate/ vigorous physical activity per hour and fewer sedentary minutes compared to other preschool children. 

Reference:  Dowda, Marsha, Brown, William H., McIver, Kerry L., Pfeiffer, Karin A., O'Neill, Jennifer R., Addy, Cheryl L., Pate, Russell R.

Policies and Characteristics of the Preschool Environment and Physical Activity of Young Children

Pediatrics 2009 123: e261-e266