Friday September 14 2007
Girls and boys should run around
Children are not meeting the internationally recommended levels of physical exercise, reported The Guardian. “To be healthy and stave off risks of obesity and linked conditions such as diabetes, youngsters are recommended to take an hour a day of moderate to vigorous exercise,” the newspaper explained. It suggested that only one in 250 girls and one in 20 boys are getting enough exercise to stay healthy. The Guardian estimated that more than 700,000 children are putting their future health at risk.
The reports are based on a relatively large and reliable study. However, as these results come from children who live in one region of the UK, we cannot say for sure that children in other regions of the UK, or in other countries would have similar levels of activity. It is worrying that children, particularly girls, do not seem to be getting enough exercise, and all children should be encouraged to be more active, and to develop healthy eating habits that will stand them in good stead in adulthood.
Where did the story come from?
Professor Chris Riddoch from the University of Bath and colleagues from the Universities of Bristol and South Carolina carried out this research. The study received funding from the US National Heart, Lung, and Blood Institute, and the UK Medical Research Council, the Wellcome Trust, and the University of Bristol. It was published in the peer-reviewed medical journal, Archives of Disease in Childhood.
What kind of scientific study was this?
This was cross-sectional analysis, looking at activity levels in 11 year olds, as part of the Avon Longitudinal Study of Parents and Children (ALSPAC).
The researchers studied 5,595 children aged 11, whose mothers took part in the ALSPAC Cohort study while they were pregnant in 1991-1992. They used a piece of equipment called an accelerometer to measure how active the children were. The accelerometer was worn on an elasticated belt for seven consecutive days, and it measured and recorded movement counts in one minute periods. Movement counters measured both the frequency and the intensity of motion. Using these recordings the researchers calculated the children’s total physical activity (average movement counts per minute) and time spent doing moderate to vigorous physical activity (defined as at least 3,600 counts per minute). They compared activity for boys and girls and for weekdays and weekends. They also looked at whether children’s levels of activity met International Task Force recommendations.
What were the results of the study?
The researchers found that on average, children spent 20 minutes per day doing moderate to vigorous physical activity. Boys were more active than girls, and spent 25 minutes per day in this kind of activity, compared with just 16 minutes for girls. Only 51 in 1,000 boys and 4 in 1,000 girls achieved the internationally recommended levels of activity, which suggest that children should engage in at least 60 minutes of moderate to vigorous physical activity a day.
What interpretations did the researchers draw from these results?
The researchers concluded that the majority of children are not sufficiently active according to current international recommendations.
What does the NHS Knowledge Service make of this study?
This was quite a large study, which seems relatively reliable. Points to consider when interpreting this study include:
- Using objective measurements, such as those supplied by the accelerometer, avoids the problem of inaccurate recall of activity, but does mean that results depend on the reliability of the equipment, and on its appropriate use and the appropriate interpretation of results. It is not clear how well the accelerometer counts correlate with different levels of activity.
- Of the children who agreed to wear the measuring equipment, about 15% did not provide enough recordings to be included in the analysis. The children who did not provide measurements were different from those who did in weight, body mass index, puberty stage, age, and gender, although the differences were reported to be small to affect the research outcome. The results may therefore not be representative of all children, and we should be cautious of extrapolating these results to all children.
- The study was conducted in one region of the UK, and may not be representative of activity levels in other areas of the UK, or other countries.
- Although the measurements were reported to have been taken between January 2003 and January 2005, we do not know whether the measurements taken were evenly spread across the year. For example, if the majority of the children were assessed during the mid-period of this time – winter 2003/2004 – we may see less activity levels than if most of the measurements were taken during the summer months.
Overall, encouraging children to be more active is a good idea, and should bring many health benefits to them both in childhood and adulthood.
Sir Muir Gray adds...
The debate on obesity has so far focussed too much on food; it is true some children need less food, but all children need more exercise. However, the ‘e’ word should never be used, it’s better to take the girls on a shopping expedition, park the car two miles from the shops and leave the credit card at home!