LONG hours spent on websites such as YouTube and Facebook and playing computer games are crippling Australian children, health experts have warned.

Children as young as five are suffering back pain from extended computer use. Many 10-year-olds spend more than five hours a day hunched over keyboards at home.

A leading researcher will tell a conference of international and Australian physiotherapists in Cairns today that if the problem is not tackled there will be an epidemic of musculoskeletal conditions and obesity-related diseases, including diabetes, heart disease and depression due to lack of exercise.