Background: Tracking refers to the tendency for an individual to maintain their rank within a group over time.

Purpose: To identify levels of pedometer determined physical activity and explore tracking over 10-year follow up period. Methods: In October of 2000, 2003, 2005, and 2010, data of physical activity as steps/day was measured with Yamax SW-200 Tokyo, Japan for 4 consecutive schooldays in 40 (19 females) Swedish individuals (mean age 12.7 in 2000).

Results: In boys a decrease of mean step/day occurred between baseline and the 3-year (P < .001), the 5-year (P < .001) and the 10-year follow-up (P < .014). A significant moderate tracking occurred in those at baseline classified insufficient active, both over the 3- to 5-year span (r(s) = 0.56, P = .005) and the 0- to 10-year span (r(s) = 0.47, P = .05).

Conclusion: The significant decrease of physical activity, as steps/day, in males at early adolescent seems to level out during late adolescence and early adulthood. Further, youth classified insufficient active according to published BMI reference standards at the baseline measures showed a significant moderate tracking over the 10-year follow-up period.