title: Ambulatory activity monitoring in youth: state of the science.
abstract: OBJECTIVE
  More than 75% of youth in grades 4 through 12 in the United States do not engage in vigorous physical activity daily. Clinicians and researchers need valid and reliable measures of physical activity to address this public health concern. The purpose of this paper is to review the history of activity monitoring in pediatrics and synthesize the current literature on ambulatory physical activity monitoring in youth.
  
  
  CONCLUSIONS
  For this review, ambulatory physical activity monitoring is defined as direct measurement of the amount of walking and/or steps taken over time. An overview of commercially available pedometers and accelerometers is presented with implications and recommendations for practice and research.
  
  
  CONCLUSIONS
  Ambulatory activity monitoring has the potential to affect current pediatric health concerns related to inactivity and clear indications for a broad spectrum of research methodology.
authors.affiliation: Department of Rehabilitation Medicine, School of Medicine, University of Washington, Seattle, WA 98105, USA. kristie.bjornson@seattlechildrens.org
authors.forename: Kristie F
authors.initials: KF
authors.lastname: Bjornson
authors.forename: Basia
authors.initials: B
authors.lastname: Belza