Office workers who spend their days sitting down are urged to exercise for at least one hour each day in order to combat the serious risks their sedentary lifestyle is posing on their health.

A major new study by medical journal Lancet– which surveyed more than one million adults globally – found that sitting for at least eight hours a day can increase the risk of premature death by up to 60 per cent.

That risk can be offset, however, by doing at least one hour of physical activity per day, such as visiting the gym, playing sports, cycling or taking a brisk walk.

Physical inactivity is linked to an increased risk of heart disease, diabetes and some cancers and is associated with more than five million deaths per year.

"There has been a lot of concern about the health risks associated with today's more sedentary lifestyles," says lead author Professor Ulf Ekelund from the Norwegian School of Sports Sciences.

"Our message is a positive one: it is possible to reduce – or even eliminate – these risks if we are active enough.

"For many people who commute to work and have office-based jobs, there is no way to escape sitting for prolonged periods of time. For these people in particular, we cannot stress enough the importance of getting exercise, whether it's getting out for a walk at lunchtime, going for a run in the morning or cycling to work.

“An hour of physical activity per day is the ideal, but if this is unmanageable, then at least doing some exercise each day can help reduce the risk.”

People who sat for eight hours a day but were physically active had a much lower risk of death, compared to people who sat for fewer hours a day, but were not physically active.

This, the report says, suggests that physical activity is particularly important, no matter how many hours a day are spent sitting.

The increased risk of death associated with sitting for eight hours a day was eliminated for people who did a minimum of one hour physical activity per day. The greatest risk of death was for people who sat for long periods of time and were inactive.

The findings are part of a four-paper series published today in The Lancet and first launched in London ahead of the Summer Olympic Games.

The authors of the series warn there has been too little progress in tackling the global pandemic of physical inactivity since the 2012 Olympics, with a quarter of adults worldwide still failing to meet current recommendations on physical activity.

The report says the threat caused by physical inactivity on public health is now as great as that of smoking – and is causing more deaths than obesity.

Commenting on the findings, ukactive executive director Steven Ward said: "It is vital that we elevate physical inactivity to become a top tier public health concern and give people more opportunities to be at active at work and at home. To turn the tide of inactivity we need to implement co-ordinated health interventions, backed by sustained investment at local, national and international level."

• To read the full report, click here to visit the Lancet website.