Exercise that gets you puffed reduces your risk of early death, according to a large Australian study that might prompt changes to exercise guidelines.

A six-year study of 204,000 people from NSW aged over 45 years found those who did vigorous exercise regularly were 13 per cent less likely to die prematurely than those who did moderate exercise.

Vigorous activity was defined as an activity that made people breathe harder, such as jogging, cycling, aerobics or competitive tennis.

Moderate activity included activities such as gentle swimming, social tennis, gardening or work around the house.

"Of course the volume of physical activity is one of the most important factors," said co-author Melody Ding, of the University of Sydney school of public health.

"But on top that, the more physical activity that is vigorous, the more protected the individual is against all-cause mortality."

Most exercise guidelines, including the Australian advice, urges adults to spend 150 minutes a week doing moderate activity or 75 minutes of vigorous activity.

But implicit in those guidelines was the amounts of moderate and vigorous activity conferred similar benefits, which was not the case, Ms Ding said.

"Those who were doing more vigorous activity had less deterioration in physical functions over time," she said.

"There could be potential cardiovascular and metabolic protection that vigorous activity offers."

The authors, writing in their study published in JAMA Internal Medicine, said although vigorous exercise was associated with an increased risk of cardiovascular events and sudden death, the absolute risk of death was extremely low.

"Therefore, in future activity guidelines, it may be reasonable to encourage wider consideration of vigorous activities for those who are capable of doing so," they said.