The average eight-year-old dons physical education kit for just over an hour a week, half the time recommended by national advisers, according to unpublished research.
Even 11-year-olds in P7 are receiving on average around 80 minutes of PE a week - less than the national target, a study of 650 primaries has revealed.
Lacking in organised physical activity, the new couch potato and computer generation - often driven to school and guarded closely by parents - is apparently failing to inject enough puff into its lungs for its own short and long-term sporting and health good.
Tommy Sheridan, Scottish Socialist MSP, raised the issue in the Scottish Parliament last week and is to table an amendment to the education Bill, calling on all primaries to establish a PE department to fuel activity.
He told TES Scotland: "My concern is primarily health-related. We have a situation among children where all the statistics show one in four kids suffer from obesity. There is a whole plethora of alternatives to physical activity that were not there 20 years ago, which are contributing to more sedentary lifestyles. The difficulty is that not one primary school in Scotland has a PE department. The idea of supervisors and visiting specialists is just not happening."
Mr Sheridan, who still plays junior football for Baillieston in Glasgow, says physical activity is the "bottom priority" in primaries: "Unless we do something about it, we'll be heading for a continuation of the underachievement that's the by-word for Scotland in terms of sport while our health is going to get worse."
A PE department in each primary may be a grandiose and unrealistic demand, given the size of the majority of schools, but action is beginning slowly in other ways via a pound;450,000 three-year programme promoted by Sportscotland. It is aiming to turn round what many believe is a damaging picture of inactivity in primary-aged pupils.
The Active Primary Schools scheme, funded from the comprehensive spending review, is being piloted in West Lothian and is likely to be tested in three or four authorities next session. It promotes activity in the curriculum, playground and after-school sport through a part-time co-ordinator working with cluster schools.
Stewart Harris, Sportscotland's head of youth sport, estimates it would cost around pound;8 million t deploy 400 full-time co-ordinators to work with clusters of primaries across the country, cash which could come from sport, education or health budgets given the cross-departmental value of the project.
"The aim of the programme is eventually to affect every primary school. We'd like to try and involve every child in Scotland. The fundamental principle is to get kids more active and improve co-ordination between agencies," Mr Harris says.
"To address concerns we have to have a different culture and a focus on physical activity and sport in primary. Kids will participate when given good opportunities and getting them when they're enthusiastic between five and eight years old is important.
"Ideally, we're asking for each child to get three periods of PE a week, after school to be given opportunities to experience a range of activities and not necessarily traditional team sports, and - while playing - to learn to socialise," he continues.
Mr Harris believes co-ordinators could deliver some PE, train primary staff through Sportscotland's TOP programme (to provide training and equipment to primary schools) establish after-school activities, and encourage others to become involved. A debate has yet to take place about who would undertake such roles, PE staff or sports development officers.
Jo Buchanan-Smith, a PE teacher at Armadale Academy seconded as part-time primary co-ordinator, says of PEin West Lothian: "We've seen levels of activity which are extremely poor. Exercise is not part of their lives at all, as they've formed no habits early on. They're coming up to secondary and offered activities they are not at all receptive to."
Mrs Buchanan-Smith believes taking on pupils' interests and concerns is vital in primary. It is one reason why playgrounds have been redesigned and new games introduced. P6 pupils are helping to supervise. "Play was the first thing we addressed, because it was one way of getting them active very quickly," she explains. "They question refereeing decisions at first, they're not able to win or lose properly."
Behaviour has improved in the playground as more pupils are more active. Mrs Buchanan-Smith reports interest in sport as "unbelievable" and with primary colleagues is planning a number of festivals and mini-tournaments. Other activities such as karate are now being introduced to complement the staple diet of football and netball.