UK children's physical activity levels have been greatly overestimated, with true levels likely to be around six times lower than national data suggest, finds research published ahead of print in the Archives of Disease in Childhood .
Annual health survey data are used to inform UK public health policy and practice, and the figures indicate that the UK population takes a lot of exercise, and that children have been increasingly physically active over the past few years.
But data collected on children's physical activity levels rely on information supplied by parents.
In a bid to assess the accuracy and reliability of this data source, the research team monitored actual levels of physical activity in 130 children aged between 6 and 7 years over one week, using a portable recording device (accelerometer) carried on a waist belt.
They compared the readings with the information supplied by their parents, using the Health Survey for England annual questionnaire.
To maintain good health and stave off obesity and other serious illness in later life, it is recommended that children engage in at least 60 minutes of moderate to vigorous physical activity every day, such as brisk walking, running, and sports.
Parents said their children were moderately to vigorously physically active for an average of 146 minutes a day.
But the accelerometer readings showed that this figure was actually 24 minutes a day, with boys managing 26 minutes and girls 22.
According to the survey data, 83% of boys and 56% of girls complied with the recommended daily amounts of moderate to vigorous physical activity.
But the accelerometer showed that only 3% of boys and 2% of girls actually did so.
The authors say that these findings back up national figures, showing an increase in car journeys children take, as well as their expanding girth.
"Marked improvements in surveillance of physical activity will be necessary in order to meet the major public health challenges of the 21 st century, particularly where physical activity has been implicated in the aetiology of diseases, such as obesity and related disorders," they comment.
Professor John Reilly, Division of Developmental Medicine, University of Glasgow, Yorkhill Hospitals, Glasgow, Scotland, UK
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Dr Ashley Adamson, Human Nutrition Research Centre, Insitute of Health and Society, Newcastle University, Newcastle, UK
Tel: +44 (0) 191 222 5276