Children in British primary schools should be tested on their fitness in the same they would on subjects such as English and maths.
Not-for-profit health body ukactive has said tests on school children's health would "stem the tide of physical inactivity threatening to overwhelm the NHS", according to a report.
The organisation has said measuring fitness levels in primary schools is "rare and at best sporadic". Only 43% of those surveyed recorded how children were using their time in PE.
As the result of a "physical inactivity pandemic" ukactive said Britain was facing "a ticking time bomb".
In a report named Generation Inactive, the health body argues schools should focus on physical education as much as they would on academic subjects and that just as parents would not accept primary school leavers to not have attained a suitable level of maths or English, the same standards should be expected with fitness.
Ukactive said only half of seven-year-olds were meeting guidelines to carry out 60 minutes a day of fitness. Schools in England aim to provide two hours of PE or sport a week for pupils aged five to 16 but the report said many still fail to achieve even that.
The health body has recommended that schools extend their fitness measurements, saying current body mass index tests are not rigorous enough. It says the government should also build PE training into English, maths and science teacher training.
"The current national ambition focused solely around PE lessons is simply not bold enough. We should aim higher and demand more," Baroness Tanni Grey-Thompson, ukactive's chair and Britain's most decorated Paralympian, said.
"The focus should be on ensuring that children are given all the necessary support possible in order to achieve the 60 minutes of daily activity recommended in the chief medical officer's guidelines.
"This does not mean we wish to see 60 minutes of timetabled PE per day. Instead, we are calling for a focus on a 'whole school approach'."
Professor Russell Viner, officer for health promotion for the Royal College of Paediatrics and Child Health, said: "At a time where children should be at their most active, it's concerning that half of seven-year-olds are not doing the recommended one hour of physical activity that's advised each day.
"The Generation Inactive report is a welcome reminder that more must be done to improve the health of our nation's children.
"A sedentary lifestyle doesn't just mean a child could be overweight, it is an issue that can affect a child's entire life, from poor concentration levels impacting on life chances post school, and increased risk of emotional and well-being issues like depression, right through to developing life-long medical conditions like type 2 diabetes – all of which can have dire consequences if not managed properly."