Key points from article :
Analysed data from almost 8,000 adults in the US aged 45 or older.
Participants wore an activity tracker for up to a week between 2009 and 2013.
On average, participants were sedentary for 11.5 hours during their waking hours.
30 minutes of low-intensity activity, instead of sitting, reduced the risk of an early death by 17%.
Increasing the activity to heart-pumping intensity reduced risk of death by 35%.
No benefits to be had if the total amount of sitting in a day remained.
Periods of activity could be as short as a minute in duration.
The study was published in the American Journal of Epidemiology.
