E30a Free Communication/Slide Determinants of Physical Activity - II
A number of longitudinal studies have reported decreases in the amount of physical activity (PA) through the adolescent years. However, there is little information regarding changes in the pattern of PA, specifically, the number and types of activities. The purpose of this study was 1) to examine changes in the number of recreational and competitive activities reported over a four-year period and 2) to determine the probability of participating in a specific activity during both year one and four of the study (PV+) and the probability of not participating in a specific activity during both year one and four of the study (PV-). Subjects included 410 male and 372 female adolescents, aged 12–15 yrs at baseline, recruited from a single school district. Past year physical activity was assessed by questionnaire. In males, the number of reported activities decreased from 7.4 to 3.5 (p < .01) and in females, the number of reported activities decreased from 6.2 to 2.4 (p < .01) over the four year study. The PV+ was .81 and .64 for moderate-vigorous (MV) and low (L) intensity activity, respectively. The PV- was .60 and .72 for MV and L intensity activity, respectively. The highest PV+ for boys was found for basketball (.71) and weight lifting (.63) and the lowest was found for bicycling (.04) and skateboarding (.09). The highest PV+ for girls was found for aerobics (.47) and softball (.45) and the lowest was found for bicycling (.02) and rollerskating (.20). The PV- for activities not reported during year one of the study ranged from .65 to 1.00 for boys and .77 to .99 for girls. Similar results, moderate PV+ and high PV-, were found for competitive activities. While overall, the amount of physical activity decreased in this group of adolescents, there was little change over the four years in the amount of time reported for specific activities. For example, among boys who reported basketball during all four years of the study, the time spent in basketball actually increased, 3.97 vs. 4.96 hrs/wk from 1990 to 1993. The results of this study suggest that the decrease in physical activity during adolescence may be due to a decrease in the number of activities. Further, it appears that there is moderate PV+ for participation in specific activities and high PV- for non-participation in specific activities during adolescence.