The British Heart Foundation has urged parents to keep an eye on their children's activity levels to reduce their chances of needing heart or obesity treatment in the future.
A new report by the charity claims that while 71 per cent of parents think their children do enough exercise, just 11 per cent of youngsters actually do the recommended amount.
With such a high proportion not achieving 60 minutes of physical activity each day, the likelihood of bringing down the UK's rate of obesity is slim.
Dr Mike Knapton, associate medical director at the British Heart Foundation, claimed: "Children aren't really any more active than they were ten years ago.
"Parents have such an important role in helping and encouraging their kids to be more active by building exercise into their everyday lives - whether that's taking part in team sports, playing outside with their friends or walking to school."
A close eye should also be kept on youngsters' dietary habits, as figures published earlier this year by the NHS Information Centre showed that just 21 per cent of boys and girls were consuming the recommended five or more daily portions of fruit and vegetables.