ABSTRACT
In general, child PA patterns vary greatly from those displayed by adults. Typically, PA among children is sporadic and varies in intensity, as children seem to have a preference for interval-type activities over more sustained types of activities.13 Children thus have less structured activity patterns than adults and their natural PA patterns are more likely to consist of short-duration bouts, especially during play, although as they mature and develop their activity patterns become increasingly more structured and similar to adult patterns of PA. For elementary-school children, it has been estimated that the majority of their activity bouts last between 3 and 22 seconds,14,15 which has considerable implications for accurately measuring, processing, and
35.1 Introduction ..................................................................................................................................................................... 385 35.2 Children ........................................................................................................................................................................... 385
35.2.1 Secular Trends of Child Leisure-Time Physical Activity .................................................................................... 386 35.2.2 Cross-Sectional Studies ....................................................................................................................................... 386 35.2.3 Cohort Studies (Longitudinal Studies) ................................................................................................................ 387 35.2.4 Intervention Studies ............................................................................................................................................. 388 35.2.5 Methodological Challenges and Future Research on Leisure-Time Physical Activity and Obesity among Children................................................................................................... 389
35.3 Adults ............................................................................................................................................................................... 390 35.3.1 Secular Trends of Adult Leisure-Time Physical Activity .................................................................................... 390 35.3.2 Cross-Sectional, Cohort, and Intervention Studies ............................................................................................. 390 35.3.3 Intervention Studies ............................................................................................................................................. 391
35.4 Summary ......................................................................................................................................................................... 391 References ................................................................................................................................................................................. 391
interpreting child PA data and indicates a need for using short-interval-type measures administered over a period of a few days in child PA research (such as accelerometers with small epoch capabilities). Among children, even more than among adults, relying on self-reported data can be questionable and, although increasingly objective methods such as accelerometers are being used in child PA research, much of the current evidence has been derived from self-reports, which may threaten the accuracy of that data.
