Do Young People Ever Sit Still? Variations in Accelerometer Counts, Muscle Activity and Heart Rate across Various Sedentary Activities in Youth

Abstract

Evidence of adverse health effects of TV viewing is stronger than for overall sedentary behaviour in youth. One explanation may be that TV viewing involves less body movement than other sedentary activities. Variations in body movement across sedentary activities are currently unknown, as are age differences in such variations. This study examined body movement differences across various sedentary activities in children and adolescents, assessed by hip-, thigh- and wrist-worn accelerometers, muscle activity and heart rate. Body movement differences between sedentary activities and standing were also examined. Fifty-three children (aged 10–12 years) and 37 adolescents (aged 16–18 years) performed seven different sedentary activities, a standing activity, and a dancing activity (as a control activity) in a controlled setting. Each activity lasted 10 minutes. Participants wore an Actigraph on their hip and both wrists, an activPAL on their thigh and a heart rate monitor. The muscle activity of weight-bearing leg muscles was measured in a subgroup (n = 38) by surface electromyography. Variations in body movement across activities were examined using general estimation equations analysis. Children showed significantly more body movement during sedentary activities and standing than adolescents. In both age groups, screen-based sedentary activities involved less body movement than non-screen-based sedentary activities. This may explain the stronger evidence for detrimental health effects of TV viewing while evidence for child sedentary behaviour in general is inconsistent. Differences in body movement during standing and sedentary activities were relatively small. Future research should examine the potential health effects of differences in body movement between screen-based versus non-screen based and standing versus sedentary activities.

Heavy screen users are the heaviest among 10,000 children

“…Nevertheless, energy expenditure has been reported to be higher during seated gaming compared with watching video on a TV in a supine position 25 . Moreover, children have been shown to not only have somewhat higher wrist-based but also thigh-based accelerometer counts, as well as higher heart rates when playing sedentary computer games compared with watching movies 26 . Other possible explanations for the stronger relationship between TV viewing and being overweight include that the children are more exposed to unhealthy food advertising when watching TV than when using the computer, which may stimulate more frequent and unhealthy food intake 19,27 .…”