Tracking of physical activity from childhood to adulthood: a review.

The aim of the article was to review studies on the tracking of physical activity in all phases of life from childhood to late adulthood. The majority of the studies have been published since 2000. The follow-up time in most studies was short, the median being 9 years. In men, the stability of physical activity was significant but low or moderate during all life phases and also in longterm follow-ups. In women, the tracking was lower and in many cases non-significant. Among both sexes, stability seems to be lower in early childhood than in adolescence or in adulthood and lower in transitional phases, such as from childhood to adolescence or from adolescence to adulthood, than in adulthood. However, the differences in the stability of physical activity between age groups and between different phases of life were small. The number of tracking studies utilising objective methods to measure physical activity was so small that systematic differences in stability between self-report and objective methods could not be determined. A factor which caused differences in tracking results was the adjustment of correlations for measurement error and other error variance. Adjusted coefficients were clearly higher than unadjusted ones. However, adjustment was done only in very few studies. If the different methods used for estimating habitual physical activity and the failure to control for important covariates in studies of tracking are taken into account, physical activity appears to track reasonably well also in the longer term, for example from adolescence to adulthood. The results of the tracking studies support the idea that the enhancement of physical activity in children and adolescents is of great importance for the promotion of public health.