Middle-aged adults who sit for more than nine hours a day are doubling their risk of early death, but walking briskly for 24 minutes can help extend life, a study suggests
Previous research has repeatedly suggested that sedentary behaviour is bad and physical activity is good for health.
During the 5.8 year follow-up 5.9 per cent of the 36,000 people in the studies had died.
Deaths fell steeply as the total amount of physical activity increased to a plateau of about 300 minutes (five hours) per day of light-intensity physical activity - such as walking - or about 24 minutes per day moderate intensity physical activity, like jogging, tennis or heavy gardening.
However the risk of dying more than doubled for people who spent more than nine and half hours sitting.
Professor Tom Yates, a professor of physical activity, sedentary behaviour and health at the University of Leicester and a co-author of the study, said: "These results are fantastic. It has previously been widely assumed that more is better in terms of physical activity for health.
“However, this study suggests health may be optimised with just 24 minutes per day of brisk walking or other forms of moderate-intensity physical activity.
"Another important finding was that spending 9.5 hours or more each day sedentary - which essentially means sitting was associated with a statistically significant increased risk of death, with each hour more above this threshold increasing the risk of death further.
“This highlights the importance of avoiding spending most of the day sitting, as well undertaking purposeful physical activity.”
Examples of light intensity activity includes walking slowly or light tasks such as cooking or washing dishes.
Moderate activity includes brisk walking, vacuuming or mowing the lawn, while vigorous activity includes jogging, carrying heavy loads or digging.
They found that higher levels of physical activity lowered the risk of death.
Dr Charlotte Edwardson, an associate professor in physical activity, sedentary behaviour and health at the University of Leicester and a co-author of the study, said: "These findings really reinforce the saying 'Doing something is better than doing nothing'.
“They show that physical activity of any intensity lowers the risk of death, so if you're someone who doesn't achieve the recommended levels of moderate intensity physical activity, then doing more light activity, for example, pottering around more at work or at home and just generally being on your feet more, will still be beneficial.
"Our results provide important data for informing public health recommendations, and suggest that the public health message might simply be "sit less, move more and more often"."
The results were published in the BMJ.