Energy expenditure in childhood…
If physical activity is to be used as a means of preventing obesity, the meaning of physical activity, in terms of energy expenditure, is relevant. The components of energy expenditure comprise the resting metabolic rate of resting energy expenditure (REE), the thermic effect of food and the thermic effect of exercise. The REE accounts for the greatest part of total energy expenditure and is proportional to lean body mass (LBM). Therefore, as LBM increases with growth, so does absolute total energy expenditure. Overweight children will have a greater total energy expenditure than their leaner peers as a result of their greater LBM. The requirements for growth on a daily basis are modest:1-2% of total energy expenditure during childhood (excluding the neonatal period where energy requirements for growth are considerably greater) and 2-4% during the adolescent growth spurt. The discretionary part of the energy expenditure equation is thus physical activity, but children’s discretionary physical activity time is often out of their direct control.
Physical Activity in childhood…
Physical activity is taken to mean any time that the child is not asleep or completely sedentary. Sedentariness is an important concept. Physical activity in children can be planned or incidental – observation would suggest that in a ‘time poor’ society the emphasis is placed on planned activity for children.
Limited episodes of vigorous activity may produce increased fitness, increased skill and increased strength, but will not produce a consistent increase in more general physical activity, which has been termed lifestyle or incidental activity.
Physical activity is a behavior. Children learn behavior’s from parents and there is general agreement from studies that parental physical activity has an influence on their children’s activity. Children are more active than their parents. Children of active parents are twice as likely to be active as children of inactive mothers, and this was increased over threefold for active fathers. There was a 6 fold increase in the activity of children if both parents were active. Maternal education level is also inversely associated with inactivity. The mechanisms for the influence of parental activity on childhood activity
Are probably multiple and include role modeling, shared physical activity, genetic influences and increased access.
Television and childhood obesity have been a topic of great interest and some debate since the publication of a seminal study by Dietz and Gortmaker in 1985. In their study they found that the prevalence of obesity in 12-17 year olds increased as the number of
Hours of television watched per day increased.
Television might influence body fatness in a number of ways. Television induces stillness that is more still than other nominated sedentary activities such as reading or drawing.
Television also influences food choices. Television time, for many, is snack time and the diversion of television will reduce the capacity to monitor total energy intake. For many families meals are taken in front of the television. Television as a childminder may reduce access to active play. Television has been more extensively investigated than other small screen leisure activities, such as computers, videos or video games, all of which may be expected to have subtly different impacts on energy expenditure.
Source: The Importance of Physical Activity in the Prevention of Overweight and Obesity in Childhood: A Review and an Opinion” by K.S. Steinbeck.