Primary school children do less exercise as they get older, according to new research.
A study funded by the British Heart Foundation found that 61% of children in Year 1 did at least an hour of 'moderate to vigorous' exercise each day, but by Year 6 only 41% achieved the target.
Researchers at the University of Bristol monitored more than 2,000 children from 57 schools in South West England during primary school using accelerometers.
The drop was particularly steep for girls, for whom the average of doing at least an hour's exercise each week fell from 54% to 28% by the time they finished primary school.
Health experts recommend that children do at least an hour of exercise every day.
Russ Jago, professor of paediatric physical activity and public health at the University of Bristol, said: 'These numbers prove that more needs be done to ensure children keep active as they approach adolescence.
'This isn't about getting children to exercise more, but rather maintaining their activity levels.'
