The school uniform, bullying and school rules have been shown to be barriers to school lunchtime play, a new study has shown.

The study based on South Australian school children aged 10-13 years, featured in the January 2012 issue of The Journal of Science and Medicine in Sport (JSAMS), published by Sports Medicine Australia, looked at the factors influencing children's activity during the 'critical' lunchtime period.

Other barriers to play included: lack of access to, and poor suitability of, space; lack of access to programs/facilities and equipment; and lack of peer and teacher support.

On the other hand, facilitators of lunchtime play included: access to equipment, enjoyment, motivation to improve skills, peer support and acceptance, and the freedom to make up or modify rules for games.

Lead study author, Rebecca Stanley from the Health and Use of Time Group, School of Health Sciences, University of South Australia says the lunchtime period is a critical window for physical activity promotion within a school day.

"According to the Australian National Guidelines, children are encouraged to obtain at least 60 minutes of moderate to vigorous physical activity a day and no more than two hours of electronic media per day," said Ms Stanley.

'School playgrounds provide important settings and opportunities for children to engage in activity, as children spend more than one-sixth of the time at school in lunch and short breaks.

"Children can obtain up to 33 per cent of their recommended daily moderate to vigorous physical activity during the lunchtime break however there is evidence suggesting that many children are not taking advantage of this time to be active.

"As there has been little research conducted into the factors influencing lunchtime play, this study is a breakthrough in understanding the barriers and facilitators of lunchtime play in the hope to better target and address the issues facing sedentary actions.

"The findings will also provide some guidance to schools, health promoters and policy makers to develop appropriately targeted lunchtime physical activity interventions or modify existing policies in order to increase children's choices and opportunities to be active at lunchtime," said Ms Stanley.