The study looked at time spent on sedentary activities
South Asian children in England do less exercise than their peers from other ethnic groups, research suggests.
Researchers said the Child Heart Health Study could explain the higher levels of heart disease and type 2 diabetes found in South Asians in adulthood.
The daily routines of 2,000 children aged nine and 10 in Birmingham, London and Leicester were studied.
Dr Mike Knapton of the British Heart Foundation said efforts were now needed to boost exercise levels in that group.
African-Caribbean and white European children also took part in the study, which was funded by the British Heart Foundation (BHF), the Wellcome Trust and the National Prevention Research Initiative.
All those involved in the study wore a small device around their waist which recorded the amount of activity and steps taken by that child each day. This was able to detail the time that had been spent doing sedentary, light, moderate and vigorous levels of activity.
British South Asian children were found to spend longer periods in sedentary activities, such as playing computer games and watching television.
Only 54% met the current recommended target of spending at least 60 minutes per day in moderate levels of activity compared with 70% of white European children and 69% of Black African Caribbean children.
Dr Christopher Owen, senior lecturer in epidemiology at St George's, University of London, who led the study, said: "This is the first study to accurately assess ethnic differences in levels of activity amongst this age group and it shows that UK children of South Asian origin are less active overall than other children living in the UK.
"Increasing levels of physical activity in children of South Asian origin may be particularly important in helping to maintain their health in the longer term."
Dr Knapton, who is associate medical director at the BHF, said: This study is another piece in the jigsaw in helping us to understand why British South Asians are at higher risk of cardiovascular disease and type 2 diabetes.
"We now need to explore how we can lessen their risk of these conditions by increasing exercise levels."
He added: "The findings could be used to inform future physical activity programmes within the South Asian population and help to tackle the inequalities which exist between children to protect their future heart health."