Scottish pupils have far less physical education than almost every other country in the developed world, a report has found.
Scotland was found to lag behind in school PE time
The findings come in a study of 30 countries by the Organisation of Economic Co-operation and Development.
To bring Scottish primary children up to the international average would mean an extra 35 hours a year.
The Scottish National Party called for more sports facilities and school time dedicated to PE.
SNP education spokeswoman Fiona Hyslop said: "The benefits of PE are well known - we know that it helps to keep ill-health at bay, we know that it helps to promote a healthy lifestyle in youngsters, and we know that it makes for better mental health.
"There is also evidence to show that a good PE regime improves pupil attainment and reduces tiredness."
Ms Hyslop said most of the 29 OECD countries were found to give more of their scheduled school time to PE than Scotland.
She added: "Our 5% means that we are third worst in primary school and second worst in the first years of secondary school."
The Scottish Executive said it accepted that the amount of exercise children do is a problem.
Ministers have recommended pupils have two hours a week and a wider choice of sports.