Tracking of physical activity from early childhood through youth into adulthood.

Purpose: The aim of the study was to investigate the tracking of physical activity (PA) from preschool age to adulthood in six age cohorts of males and females.

Methods: A random sample of 3596 boys and girls age 3-18 yr participated in the Cardiovascular Risks in Young Finns Study in 1980. The follow-up measurements were repeated in 1986, 1992, 2001, and 2007. The PA was measured by mother's report in 3- and 6-yr-olds and self-report in 9-yr-olds and older. Tracking of PA was analyzed using the Spearman rank-order correlation and a simplex model.

Results: Mother-reported PA at age 3 and 6 yr significantly predicted self-reported PA in youth and in young adulthood, and there was a significant indirect effect of mother report on adult PA 2007 in males. Simplex models that fitted the data very well produced higher stability coefficients than the Spearman rank-order correlations showing moderate or high tracking. The tracking was higher in males than that in females.

Conclusion: This study has shown that physically active lifestyle starts to develop very early in childhood and that the stability of PA is moderate or high along the life course from youth to adulthood.