The more active a mother is, the more physically active her child will be, suggests a UK study of 500 mums and four-year-olds.

But many mothers' exercise levels fell way below recommended levels, it said.

Researchers from Cambridge and Southampton universities used heart-rate monitors to measure activity levels over seven days.

The study, published in Pediatrics, said policies to improve children's health should be aimed at mothers.

Children are not "just naturally active", it concluded, and parents have an important role to play in developing healthy exercise habits early on in life.

(BBC)