OBJECTIVE:

The goal was to examine the longitudinal associations of changes in television viewing and other sources of sedentary behavior with changes in leisure-time moderate/vigorous physical activity in adolescence.

METHODS:

We studied a cohort of 6369 girls and 4487 boys who were 10 to 15 years of age in 1997. During each of 4 years of follow-up assessments, participants self-reported their weekly hours of television viewing. By using a seasonal questionnaire, we also obtained detailed information on physical activities over the previous year, from which we calculated total leisure-time moderate/vigorous physical activity. We performed linear regression analyses to assess the longitudinal associations between 1-year changes in television viewing and 1-year changes in leisure-time moderate/vigorous physical activity during the same year, using data from 1997 through 2001.

RESULTS:

One-year changes (mean +/- SD) were -0.13 +/- 7.2 hours/week for leisure-time moderate/vigorous physical activity, -0.55 +/- 7.0 hours/week for television viewing, and -1.02 +/- 11.0 hours/week for total sedentary behaviors. In longitudinal models adjusted for age, age2, gender, race/ethnicity, Tanner stage, menarche (in girls), baseline physical activity, and baseline television viewing, we found no substantive relationship between year-to-year changes in television viewing and changes in leisure-time moderate/vigorous physical activity (0.03 hours/week, for each 1-hour/week change in television viewing). There were no material associations in age or gender subgroups.

CONCLUSIONS:

In this longitudinal study, changes in television viewing were not associated with changes in leisure-time moderate/vigorous physical activity. Our findings suggest that television viewing and leisure-time physical activity are separate constructs, not functional opposites.