Swapping an hour of sitting for walking or other moderate to vigorous physical activity can increase a person's lifespan by as much as 12 to 14 per cent, the research shows.

The data will be presented at Sports Medicine Australia's be active 2014 conference, which runs in Canberra this week.

Associate Professor Emmanuel Stamatakis from the Charles Perkins Centre at the University of Sydney said the data came from the 45 and Up Study managed by the Sax Institute in partnership with Cancer Council NSW.

More than 200,000 NSW men and women aged 45 and older participated in the study between 2005 and 2009, and the first major follow-up of participants began in 2012.

Other partners in the study included the National Heart Foundation of Australia (NSW Division); NSW Ministry of Health;  the NSW Department of Family and Community Services and its Ageing, Disability and Home Care agency; and the Australian Red Cross Blood Service.

Based on statistical modelling, the research found that replacing a realistic amount of daily sitting time with equivalent amounts of even very light physical activity could result in considerable and important health benefits, Associate Professor Stamatakis said.

"The most important message here is that any movement matters. We need to find ways to be more active and it doesn't matter what we do," he said.

The conference's keynote speaker, Active Living and public health expert Professor Stuart Biddle from Victoria University, said incidental exercise such as a standing at a desk or standing while talking to someone could be beneficial.

Other easy options included walking around the office more or using stairs instead of a lift, he said.

"We've lost that incidental activity and it's definitely causing health problems," he said.

"We need to break up these habits we have and sometimes you need something in your environment to do that. If you have the opportunity to stand, you should."

Professor Biddle believed workplaces should be structured to "nudge" people into different behaviour and action was needed to address the 50 per cent of the day most people spent sitting.

"If you go into a meeting and others are standing up, it prompts others to stand up," he said.

"You are going to be using a little bit more energy. [It] will be relatively small, but it all makes a difference."

Other research to be presented at the conference has found that older, unmarried men who were educated and worked full time, with a high income, tended to spend more time sitting than other demographics.

Living in non-urban areas, being obese and having a severe physical limitation were also factors associated with prolonged periods of sitting and a consequent great risk of chronic disease, said Professor Ron Plotnikoff, director of the Priority Centre for Physical Activity at the University of Newcastle.

"This study is identifying our population who might be more at risk of this unhealthy behaviour of prolonged sitting," he said.

Professor Biddle said the science was not yet settled on how many hours people should move from a seated position.

But a general guideline to reduce and break up sitting would be to stand for five minutes in every half hour for those who work at a desk, he said.

Associate Professor Stamatakis believed it would soon be imperative for employers to offer workers opportunities to be more active.

"Activity-based working is an example and it's a very interesting concept because it moves away from sitting fixed all day in front of a computer; it incorporates more movement," he said.

"I am sure there are other ways to optimise activity-based working to gear it towards even more physical activity during the work day."

He said there must be investment in research into the toll of excessive sitting in terms of chronic disease.

"We know it's perhaps the number one reason, cause of chronic disease and how much do we invest? Peanuts," he said.

"There are implications for employers but the key message is we need some substantial research investment to find ways to incorporate more movement into people's everyday lives."