RIDDOCH, C. J., L. B. ANDERSEN, N. WEDDERKOPP, M. HARRO, L. KLASSON-HEGGEBØ, L. B. SARDINHA, A. R. COOPER, and U. EKELUND. Physical Activity Levels and Patterns of 9- and 15-yr-Old European Children. Med. Sci. Sports Exerc., Vol. 36, No. 1, pp. 86–92, 2004.
Purpose: The purpose of this study was to assess physical activity levels and patterns from children participating in the European Youth Heart Study (EYHS). Very limited physical activity data exist that have been collected from representative samples of children and even fewer data collected where physical activity has been measured using objective methods.
Methods: Subjects were 2185 children aged 9 and 15 yr from Denmark, Portugal, Estonia, and Norway. Physical activity data were obtained using MTI (formerly CSA) accelerometers. The primary outcome variable was established as the child’s activity level (accelerometer counts per minute). Children wore the accelerometer for 3 or 4 d, which included at least 1 weekend day.
Results: Boys were more active than girls at age 9 (784 ± 282 vs 649 ± 204 counts·min−1) and 15 yr (615 ± 228 vs 491 ± 163 counts·min−1). With respect to time engaged in moderate-intensity activity, gender differences were apparent at age 9 (192 ± 66 vs 160 ± 54 min·d−1) and age 15 (99 ± 45 vs 73 ± 32 min·d−1). At age 9, the great majority of boys and girls achieved current health-related physical activity recommendations (97.4% and 97.6%, respectively). At age 15, fewer children achieved the guidelines and gender differences were apparent (boys 81.9% vs girls 62.0%).
Conclusions: Accelerometers are a feasible and accurate instrument for use in large epidemiological studies of children’s activity. Boys tend to be more active than girls, and there is a marked reduction in activity over the adolescent years. The great majority of younger children achieve current physical activity recommendations, whereas fewer older children do so—especially older girls.
The European Youth Heart Study (EYHS) is a multicenter, international study addressing the prevalence and etiology of cardiovascular disease (CVD) risk factors, including physical activity, in children aged 9 and 15 yr. Very limited physical activity data exist that have been collected from representative samples of children and even fewer data collected where physical activity has been measured with precision (18). Despite this lack of accurate data, suspicions that children are insufficiently active continue to grow—mostly as a result of indirect evidence suggesting that children are getting fatter (13). Recommendations for healthy levels of physical activity for children have been established (3), but lack of measurement precision has made it virtually impossible to accurately assess proportions of children meeting the recommendations.
The principal barrier to progress in this field has been the lack of a valid measurement instrument that can capture the full complexity of physical activity behavior in children. This is particularly true of children’s unplanned, play, or “lifestyle” activities (11). These types of physical activity cannot be assessed by self-report methods and yet children—especially younger children—perform large amounts of such activities, characterized by numerous short bursts of activity lasting mere seconds, interspersed with similar periods of recovery (2). Accordingly, lacking such basic information, we are currently unable to establish public health policy in the field of children’s activity with any confidence (17).
The use of objective motion sensors—which provide more precise estimates of activity—has now been shown to be valid (7), reliable (14), and feasible in large studies (17). For the first time, there is an opportunity to assess the physical activity levels and patterns of children with far greater confidence. Accordingly, these more accurate data can tell us how active children are, the periods of the day, week, and year when children are most (and least) active, and the balance of light, moderate, and vigorous activities in which children participate. These data are important, as it can inform public health policy in two ways. First, more accurate quantification of levels of activity adds strength to observed relationships with health risk factors (e.g., obesity), enabling more valid recommendations for children’s activity to be formulated. Second, information on children’s patterns of activity, together with the factors that influence them, can inform the design and delivery of public health interventions to promote physical activity in children. The purpose of this study was to assess objectively measured physical activity levels and patterns from children participating in the EYHS.