Physical activity of young people: the Amsterdam Longitudinal Growth and Health Study

Purpose: To describe the natural development of habitual physical activity behavior (HPA) of young Dutch male and female subjects between the ages of 13 and 27, using data from the Amsterdam Longitudinal Growth and Health Stu dy. Methods: HPA was measured by means of a structured interview at ages 13 , 14, 15, 16, 21, and 27 and concerned all activities (at work school, duri ng leisure. organized and nonorganized sports, and active transportation) e xceeding a Level of intensity of 4 METs. Complete longitudinal data concern 98 female and 83 male subjects. MANOVA for repeated measurements were done for total HPA (expressed in min.wk(-1) and in METs.wk(-1)). Similar analys es were done for organized sports activities, leisure time activities, and all "other'' activities separately (also min.wk(-1) and METs.wk(-1)),as wel l as for weekly time at three different levels of intensity of HPA, i.e. 4- 7 MET (moderate), 7-10 MET (vigorous), and >10 MET (very vigorous). Results : Our data showed regarding total HPA (min.wk(-1)) in male, but not in fema le, subjects a significant decrease in weekly time spent on HPA between the ages of 13 and 27. Regarding the three different levels of intensity in ma le and female subjects, a significant increase was found in time spent on m oderate activities, where female subjects were spending significantly more time on moderate activities than male subjects; both in male and female sub jects, a significant decrease was found in time spent on vigorous activitie s: in male subjects a significant decrease was found in time spent on very vigorous activities, whereas in female subjects time spent at this level of activity remained more or less stable. For the total weighted activity sco re (MET.wk(-1)), a significant decrease was found for both male (42%) and f emale subjects (17%). This decrease was significantly greater for male than for female subjects. Regarding more specific activities, it was found that in the course of time organized sports activities became relatively more i mportant contributors to both weekly HPA time and energy expenditure, both in male and female subjects. Conclusions: Our data show a considerable decr ease in HPA over a 15-yr period of time, both in male and female subjects. Differences between male and female subjects are predominantly caused by di fferences in time spent in moderate and very vigorous activities. In the co urse of time, organized sports activities became a relatively more importan t contributor of weekly HPA.