Long, unbroken stretches of sitting time are common among Australian 11-12 year olds, according to a national snapshot of pre-teen health and disease development.
The Murdoch Children’s Research Institute’s Child Health CheckPoint reveals that this age group spends an average of 11 hours each day sedentary. By comparison, their parents spend nine hours sitting still.
The study, done jointly with the University of South Australia, examined physical activity and sedentary behaviour of 1261 children aged 11-12 and 1358 of their parents over one week.
Professor Timothy Olds of University of South Australia’s Alliance for Research in Exercise, Nutrition and Activity (ARENA) said the results, published in BMJ Open, show that Australian children have high levels of sitting and only modest levels of physical activity.
“Previous Australian research found high levels of sedentary time tended to comprise about 40 per cent screen time and 25 per cent sitting at school, with the rest taken up with sedentary social occasions, eating and passive transport,” Prof Olds said.
“There is mounting evidence that while not all types of sedentary time are equally harmful, television is especially linked to unfavourable health outcomes. It may be that the makeup of sedentary time is as important as the overall duration.”
In the study, the children and parents wore a wrist accelerometer for eight days. Researchers then classified every minute of waking time while wearing the device as either sedentary, or light, moderate or vigorous physical activity.
According to the Australian Government’s Physical Activity and Sedentary Behaviour Guidelines, children aged five to 12 years should get at least 60 minutes of moderate to vigorous physical activity daily, while those aged over 18 years are advised to do a minimum 30 minutes at least five times a week. The guidelines also encourage people to break up long periods of sitting and to limit screen time for children in this age group to no more than two hours a day.
While the accelerometer could not distinguish between different types of sedentary time, the data did reveal that children had longer unbroken sedentary periods than their parents.
Prof Olds said that in many cases the device recorded such extended periods of stillness that researchers thought the child might have fallen asleep. It was only after cross-checking with the self-reported time-use recalls that they found the kids were in fact awake and watching TV.
He said watching shows or videos on TV or devices was even more sedentary than gaming, which required some level of interaction.
“Hours spent watching TV use may be a marker of general household dysfunction, poor routines and less emphasis on health. The more hours of TV, the worse outcomes across the board from blood pressure to academics and quality of life,” Prof Olds said.
He said that while active parents tended to have more active kids, the link between parent and child activity levels was not particularly strong.
• Funded by the Federal Government, the Child Health CheckPoint study is nested within the Growing Up in Australia study, which is run by the Department of Social Services, Australian Institute of Family Studies and
Australian Bureau of Statistics. The Child Health CheckPoint was supported by the National Health and Medical Research Council (Project Grants 1041352, 1109355), Royal Children’s Hospital Foundation (2014-241),
Murdoch Children’s Research Institute, National Heart Foundation of Australia (100660), Financial Markets Foundation for Children (2014-055, 2016-310) and the Victoria Deaf Education Institute.
Available for interview:
• Professor Timothy Olds, University of South Australia
• Professor Melissa Wake, Child Health CheckPoint chief investigator
Christine Tondorf Bridie Byrne
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