Unless youngsters are encouraged to do more exercise and eat less, the number of premature deaths from coronary heart disease will rise after years of successful campaigns to reduce the rate, it was claimed by a report published yesterday by the British Heart Foundation.
More than a third of children in England and Wales do not reach even minimum recommended exercise levels, says the report.
Children aged five to 18 should participate in at least one hour of moderately intense activity such as cycling, running, dancing or sports every day, according to guidelines set down by the Health Education Authority.
But 33% of boys and 38% of girls aged two to seven are not meeting these minimum levels, and by the time they are 15, two thirds of girls do so little exercise that they are classified as "inactive".
The report found that 75% of 11 to 16-year-olds watch more than two hours of television a day and more than a quarter spend more than four hours a day in front of the box.
The British Heart Foundation was highlighting the report as it launched its `Kids on the Go' campaign aimed at encouraging parents to ensure their children take more exercise.
Coronary heart disease is the most common cause of premature deaths (deaths under 75) in the UK.
It accounts for 26% of premature deaths among men and 17% in women, with 147,000 people dying from the disease every year.
The British Heart Foundation sponsor the London to Brighton bike ride each year.