Primary schools need to bring back afternoon breaks to meet the social and physical needs of children with disabilities, according to a report.
It also recommended an audit of all primary school playgrounds to examine how they are accessed, the use of fixed equipment, as well as details of playing surfaces.
The study, from the Joseph Rowntree Foundation and the National Children's Bureau, found that barriers remained to integrating those youngsters with physical difficulties into mainstream schools.
Researchers, led by Helen Woolley of Sheffield university, found that only one primary school of the six taking part in the study had an afternoon break for children. This created few opportunities for pupils of different ages and mobility to interact.
In some cases, breaktime was used for routine reviews of a disabled child's educational progress, or for treatments such as physiotherapy.
Disabled pupils also needed longer to eat their lunch or to go to the toilet. By the time they entered the playground, games were under way and they had lost the opportunity to join in.
The study said: "Schools that have reduced the length of playtimes, or have stopped having an afternoon playtime, should reconsider this in light of the importance of the opportunities playtimes offer for the social, physical and academic development of all children."
Another barrier to inclusion was the quality of staff training and the balance between risk and health and safety matters.
The study, Inclusion of Disabled Children in Primary School Playgrounds, found that the training centred mainly on issues of health and safety, rather than on the use of intervention to help promote greater inclusion.
Adults often feared children would harm themselves, when the sense of achievement gained from overcoming an obstacle or playing freely with their classmates could have improved their self-esteem and physical well-being.
The study said: "Staff should be helped to understand the constructive and supporting, but not dominating, role that they can take in the playground with respect to disabled children's play. This could be by awareness training and a mentoring system."
It went on: "Personal support assistants, lunchtime supervisors and class teachers should be offered and receive a variety of training relevant to their situation and responsiblities.
"This might include how to be sensitive to the dynamics of play and inclusion, and how to identify when children might benefit from adult intervention to increase their participation and confidence in play."
However, able-bodied children were often ingenious in modifying their games to accommodate classmates with physical disabilities. One girl made up dances which involved turning her friend around in her wheelchair. Others adapted games of tag which involved less running around.
Helen Woolley, director of Sheffield university's centre for the study of children and youth, is the person who co-ordinated the research.
"Children who do not take part in the initiation of play because they have been left behind for some reason lose out during play-times and it can lead to exclusion," she said.
"However, we were delighted that children modified their games and brought down some of those social barriers. We were not expecting this to happen to the extent that it did."
Joanna Ryam, national development director of the disabled children's charity, Kids, which promotes inclusion through play, said: "It is unacceptable that in some schools individual procedures for disabled children are carried out during breaktimes. This is not only detrimental to their health and well-being, but contravenes legislation which requires schools to ensure they do not treat disabled children less favourably than other children.
"We urge all schools to review their procedures as a matter of urgency."
She believes that staff should be offered training for organising play that is fully inclusive to allow disabled children to take risks in the games they play and test their physical boundaries to their limits.
Adrian Voce, director of the Children's Play Council, said: "Children's play has become undervalued in recent years. Its significance to children's quality of life now, and to their future development, cannot be underestimated. It is a medium for so much of the informal learning and growth that cannot be gained from the classroom."
Further information about the report can be obtained from Helen Woolley at: email@example.com