Purpose: To examine secular trends, seasonal and socioeconomic differences in physical activity participation among Australian adolescents in 1997 and 2004.
Methods: Repeat cross-sectional school survey, conducted in 1997 and 2004. School students were randomly selected from grades 8 and 10 in New South Wales Australia (1997, N = 2026; 2004 N = 1771). Time spent in moderate-to-vigorous physical activity (MVPA) was assessed by self-reported participation in organized and nonorganized physical activity separately for summer and winter by sex, grade, and socioeconomic status (SES).
Results: Between survey periods, the proportion of students reporting ≥ 60 mind-1 of MVPA increased, except among grade 10 boys during winter. MVPA (mind-1) increased among all groups during summer school terms, During winter school terms, MVPA was relatively stable between surveys for grade 8 students but inconsistent among grade 10 students. Organized MVPA increased among all groups in both summer (19 - 49 mind-1) and winter (7-21 mind-1) school terms. Participation in nonorganized MVPA increased only during summer school terms (4-32 mind-1) and decreased during winter school terms (7-17 mind-1). MVPA increased consistently among students in the high-SES group compared with other SES groups, independent of season, and in some cases MVPA decreased in low-SES groups during winter school terms.
Conclusion: Overall, the patterns of change were similar for boys and girls, with substantial increases in summer school terms and insubstantial changes during winter school terms (with the exception of a decrease among grade 10 boys). There was a direct association between change in participation in MVPA and SES, indicating that interventions are required to focus on the needs of less-advantaged students.