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Background
Many health promotion programmes for physical activity are targeted during childhood and adolescence, as these life stages are seen to be important for the development of health behaviours. The underlying assumption is that physical activity will become habitual or “track” (ie will be a stable aspect of behaviour between different ages). Given the considerable variation between studies in the extent to which physical activity demonstrates tracking, this systematic review examined studies that provided data on the tracking of physical activity behaviours in children and young people.
Methods
Seven bibliographic databases were searched systematically in July–August 2008 using search strategies built around three groups of keywords: physical activity, study type, young people. Studies had to be prospective, longitudinal studies that reported data on any physical activity behaviour for at least two time-points (⩾2 years apart). The study was restricted to community-based populations who were ⩽18 years at baseline. Two reviewers independently undertook data extraction from all suitable papers, and performed quality appraisal.
Results
The database search yielded 10 685 titles, from which 59 were included in the review. There were only 15 papers that specifically examined tracking of physical activity behaviours. Tracking co-efficients ranged from −0.11 to 0.59; all indicating low or moderate tracking of physical activity, with no clear differences between males and females. Moderate tracking was observed in studies where follow-up was five years or less. The highest degree of tracking was observed for club sport participation and even over long follow-up, sports training and organised physical activity showed higher tracking than other physical activity behaviours. Physical activity levels declined consistently during adolescence, as did sports participation. However, the decrease in physical activity was less marked among those who participated in sports in early adolescence, and those who participated with parents or at high levels. The likelihood that young people continue with specific sports over short periods is generally low, but the likelihood that they continue to take part in any team, individual or vigorous activity is higher.
Conclusions
In general, tracking of physical activity behaviours between childhood, adolescence and young adulthood is low, but the evidence is limited. Levels of physical activity during childhood/adolescence decrease with age. Research is needed to explore the reasons why adolescents and young adults give up physical activity and participation in sports, although there are several factors in adolescence that do lessen the chances of being inactive at a later age.