ABSTRACT. Objective. Recommendations for adult physical activity have shifted from 20 to 60 minutes of continuous vigorous activity 3 to 5 times a week to accumulation of 30 minutes of moderate to vigorous physical activity most days of the week. Variations of these guidelines also have been suggested for children, based on the idea of accumulating moderate to vigorous physical activity throughout the day, rather than attaining vigorous physical activity in continuous blocks. The goal of this study was to assess accumulated amounts of physical activity at different intensities in children.Methods. We reviewed 26 studies (n ‫؍‬ 1883) in youth aged 3 to 17 years that used heart-rate recording to measure physical activity in children to determine accumulated daily activity. Included were studies that provided time being active for at least 2 heart rate intensities at or above 120 beats/minute. Descriptive characteristics of the study groups were determined, and the influence of age, gender, and hours and days of observation on the slope of activity time as a function of percentage of heart rate reserve (HRR) was determined using hierarchical linear regression.Results. Youth attained 128.0 ؎ 45.6, 47.1 ؎ 14.9, 29.3 ؎ 13.7, and 14.7 ؎ 6.0 minutes/day between 20% to 40%, 40% to 50%, 50% to 60%, and greater than 60% HRR, respectively. Age was a significant predictor of the intercept and slope of the physical activity and %HRR relationship.Conclusion. Youth of all ages attain >60 minutes/day of low-intensity physical activity and approximately 30 minutes/day of activity at traditional cardiovascular fitness training levels of 50% or more of HRR. Recommendations for youth activity are discussed. Pediatrics 2001; 108(3). URL: http://www.pediatrics.org/cgi/content/full/ 108/3/e44; activity, heart rate, exercise intensity, exercise duration.ABBREVIATIONS. ACSM, American College of Sports Medicine; CDC, Centers for Disease Control and Prevention; HRR, heart rate reserve; bpm, heart beats per minute; VO 2max , maximal oxygen consumption; METS, metabolic equivalents; MVPA, moderate to vigorous physical activity.T he importance of a physically active lifestyle for reducing the risk of morbidity and mortality is well documented. 1,2 To encourage adoption of active lifestyles, the American College of Sports Medicine (ACSM) developed guidelines for the amount of physical activity required to produce health benefits. The original guidelines for youth and adults recommended attainment of 3 to 5 sessions of 20 to 60 minutes of continuous, high-intensity physical activity per week. 3 On the basis of epidemiologic and controlled research in adults on the health benefits of lower-intensity, less-structured physical activity 4,5 and the small percentage of the population who met original guidelines 6 and because modest increases in physical activity were most beneficial for those who were most sedentary, 4,5 the ACSM and the Centers for Disease Control and Prevention (CDC) revised the physical activity guidelines. The current recommendat...

The purposes of this study were to measure the level and pattern of moderate-to-vigorous physical activity (MVPA = > 4.5 METs) and examine predictors of activity in obese children. Fifty-one 8-12-year-old children seeking obesity treatment wore accelerometers for 3 or 4 days. Children averaged 12.2 bouts of MVPA per day that lasted an average of 4.2 min, while parents engaged in 3.9 bouts of MVPA that lasted 4.2 min. Hierarchical regression models showed parent activity improved the prediction of obese children's activity levels and the number of bouts of MVPA but not the duration of MVPA. These results suggest that programs to increase physical activity in obese children should structure the activity in short bouts and attempt to increase parental physical activity.