title: Systematic review of physical activity and cognitive development in early childhood.
abstract: OBJECTIVE
  To comprehensively review all observational and experimental studies examining the relationship between physical activity and cognitive development during early childhood (birth to 5 years).
  
  
  METHODS
  Systematic review.
  
  
  METHODS
  Electronic databases were searched in July, 2014. No study design, date, or language limits were imposed on the search. Included studies had to be published, peer reviewed articles that satisfied the a priori determined population (apparently healthy children aged birth to 5 years), intervention (duration, intensity, frequency, or patterns of physical activity), comparator (various durations, intensity, or patterns of physical activity), and outcome (cognitive development) study criteria. Study quality and risk of bias were assessed in December 2014.
  
  
  RESULTS
  A total of seven studies, representing 414 participants from five different countries met the inclusion criteria, including two observational and five experimental studies. Six studies found increased or higher duration/frequency of physical activity had statistically significant (p<0.05) beneficial effects on at least one cognitive development outcome, including 67% of the outcomes assessed in the executive function domain and 60% in the language domain. No study found that increased or higher duration/frequency of physical activity had statistically significant detrimental effects on cognitive development. Six of the seven studies were rated weak quality with a high risk of bias.
  
  
  CONCLUSIONS
  This review provides some preliminary evidence that physical activity may have beneficial effects on cognitive development during early childhood. Given the shortage of the information and the weak quality of available evidence, future research is needed to strengthen the evidence base in this area.
authors.affiliation: Faculty of Physical Education and Recreation, University of Alberta, Canada. Electronic address: vlcarson@ualberta.ca.
authors.forename: Valerie
authors.initials: V
authors.lastname: Carson
authors.affiliation: Faculty of Physical Education and Recreation, University of Alberta, Canada.
authors.forename: Stephen
authors.initials: S
authors.lastname: Hunter
authors.affiliation: Faculty of Physical Education and Recreation, University of Alberta, Canada.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Kuzik
authors.affiliation: Department of Psychology, University of Alberta, Canada; Neuroscience and Mental Health Institute, University of Alberta, Canada.
authors.forename: Sandra A
authors.initials: SA
authors.lastname: Wiebe
authors.affiliation: Faculty of Physical Education and Recreation, University of Alberta, Canada.
authors.forename: John C
authors.initials: JC
authors.lastname: Spence
authors.affiliation: Department of Psychology, University of Alberta, Canada.
authors.forename: Alinda
authors.initials: A
authors.lastname: Friedman
authors.affiliation: Healthy Active Living and Obesity Research Group, Children's Hospital of Eastern Ontario Research Institute, Canada; Department of Pediatrics, University of Ottawa, Canada.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Tremblay
authors.affiliation: John W. Scott Health Sciences Library, University of Alberta, Canada.
authors.forename: Linda
authors.initials: L
authors.lastname: Slater
authors.affiliation: Center for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Australia.
authors.forename: Trina
authors.initials: T
authors.lastname: Hinkley
mesh_terms: D002657:Child Development; D002675:Child, Preschool; D000068456:Clinical Studies as Topic; D003071:Cognition; D015444:Exercise; D006801:Humans; D007223:Infant; D007231:Infant, Newborn
keywords: Child preschool; Executive function; Growth & development; Infant; Language; Physical activity