Housework, gardening or ambling around the golf course are not enough to stay fit and people must work up sweat if they want to avoid an early death, a new study suggests.

Taking part in vigorous exercise for at least 45 minutes a week is essential for health and guidelines should be changed to help people realise they must work harder, say researchers.

The government's Change4Life campaign advises people that housework, washing the car or taking the dog for a walk can be beneficial for health. But unless those activities are combined with more intense work outs, they are unlikely to ward off illnesses like heart disease or diabetes.