Politicians will sweat it out in a new, apolitical arena to prove they are "fit" for office.

A host of federal MPs, senators and staffers will take part in AUSactive's four-week cardio challenge to promote the importance of regular physical activity.

Former Wallabies captain David Pocock, independents Allegra Spender and Sophie Scamps and Regional Development Minister Kristy McBain are among the politicians signed up for the program beginning on September 25.

Each participant will track their exercise with heart rate monitors that calculate "effort points".

Winning titles will be awarded to the MP and office that earn the most points.

Assistant Minister for Competition Andrew Leigh told reporters he hopes his participation in a 100km race on Sunday alongside his ironman triathlon training will put him ahead of his parliamentary colleagues.

"Each of us have run for parliament so we can sit in office, but the aim of this AUSactive campaign is to ensure that Australians are doing more running and less sitting," Dr Leigh said.

Greens senator Dorinda Cox said it was a great opportunity to promote the mental and physical benefits of exercise, while independent Helen Haines said politicians didn't need to run a marathon to improve their activity levels.

AUSactive board director Emmett Williams says the campaign aims to encourage politicians to lead by example.

Australia's health record is far from perfect, with the nation ranked 140 out of 146 OECD nations for adolescent physical activity. Two out of three adults are obese or overweight while more than half fail to meet recommended exercise guidelines.

Mr Williams believes encouraging Australians to exercise is an effective measure that could relieve an already stretched health system.

"Physical inactivity is very, very costly - not just from a socio-economic perspective but from a raw economic perspective," he told reporters.

"We spent $27 billion a year as a country dealing with chronic illness and the solution is preventative."