Forty per cent of the primary schools examined in a survey in Cork and Kerry have an official policy of not allowing children to run in the school yard, while most of the shoolchildren surveyed have less than 40 minutes' exercise in physical education classes each week.
These findings are contained in a major study of childhood obesity carried out by the Health Service Executive (HSE) in its southern area.
The study, Our Children, Their Future, Why Weight?, also identified "worrying trends" in relation to the patterns of eating and exercise in the home.
The report found that a third of the families surveyed ate weekday meals while watching TV, 30 per cent of children daily ate breakfast on their own, and families preferred sedentary activities such as going to the cinema rather than active pursuits such as walking or swimming.
It also revealed that one-third of young children surveyed had a television in their bedroom and that the most popular channels were those on satellite and cable, not covered by the Broadcasting Commission of Ireland's code on children's advertising.
The report was based on four studies conducted in Cork and Kerry, as well as a review of literature on childhood obesity.
Research into school exercise found that 88 per cent of children surveyed only had one PE session in the school week and that 40 per cent of primary schools surveyed had banned running in the school yard.
At the publication of the report, Dr Margaret O'Sullivan, a specialist in public health medicine, said many schools adopted the no-run policy because of the size of playgrounds and the number of pupils rather than for insurance purposes.
Child-directed advertising was also found to be an area of concern, with 50 per cent of parents claiming that their children had put pressure on them to buy certain food or drinks as a result of TV ads.
"Pester power" was found to be alive and well, with only a minority of parents reporting that they never gave in to pressure to buy particular sweets or soft drinks.
Fast food or convenience foods were found to be the most common options in school canteens.
Snack-food vending machines are becoming increasingly popular, with 58 per cent of schools surveyed having at least one on site.
The report argued that supportive strategies for parents were needed, that campaigns to reduce television watching should be considered and that using TV to promote healthier lifestyles to children should be examined.
The National Obesity Taskforce chairman John Treacy said schools needed to introduce daily physical education classes.
They often fell into the trap of focusing on academic performance to the detriment of the health and wellbeing of students at primary and post-primary level.
"Children need to be active every day of the week. Once a week is not enough," Mr Treacy added. "I strongly believe that sport and PE should be a fundamental part of every child's development, and we need to get that message across. Children's health is as important as English and maths."
He said the onus was on parents to set a good example to their children by engaging in regular physical pursuits.